Paper Test Equipment

Paper Test Equipment According to TAPPI Standard

Bandung Science and Technology Institute

by:

1. Damayanti Susanti Anggraini [012.12.009]

2. Andi Lukman Hakim [012.12.010]

3. Ahmad Robbi Maulana [012.12.011]

4. Anna Christina Margaritha [012.12.012]

5. Windi Yolanda Silfi [012.12.013]

6. Dedeh Winingsih [012.12.014]

7. R. Akbar Ramadhan Syambas [012.12.015]

8. Dwi Anggorowati [012.12.016]

ROUGHNESS OF PAPER AND PAPERBOARD

(PRINT-SURF METHOD)

TAPPI STANDARD T-555

This method measures the roughness of paper and paperboard under condition intended to

simulated the nip pressures and backing substrates found in printing processes. It is

applicable to coated and uncoated papers and paperboards which are intended to be printed

by contacting printing processes. The measuring principle, that of determining the resistance

to flow or air between the test surface and a metal band in contact with it, is similar to that

employed in TAPPI Test Method T 538 om-96 “Roughness of paper and paperboard

(Sheffield Method).” The major difference between this and other air leak methods is that the

metal band dimensions, clamp pressures and composition of the measuring nip are all

intended to simulate printing process conditions.

Significance

Surface roughness is a significant factor in determining the printability of papers and

paperboards. By measuring roughness under conditions approximating letterpress, litho and

gravure printing processes this method yields information relevant to the performance of the

product during printing. The results of the test are expressed directly as an average value of

roughness in micrometers, which in many cases correlates better with printability than other

comparable methods. In some cases, it is possible to relate average roughness to ink film

thickness, thus providing guidance on setting printing conditions.

Definition

1. Print-surf roughness. The mean gap between a sheet of paper or board and a flat circular

land pressed against it under specified conditions.

2. Print-surf compressibility,K. The percentage decrease in surface roughness when

measurements are made consecutively at two of the standard clamping pressures

specified in this method. The surface compressibility, K, can be defied mathematically

by the equation :

K = 100 (G1 – G2)/G1

Where G1 and G2 are the surface roughness values obtained at the two clamping pressures,

with G1 being the lower pressure.

Testing Instrument

Developed from Dr. John

Parker’s original method, the

Parker Print-Surf is a

microprocessor-controlled

instrument, which perform

high speed, precision

measurements of paper

surface roughness under

conditions that simulate those

encountered during the printing process. The specimen is clamped between a precision

engineered measuring head and a specially designed backing assembly. The resistance to

airflow is measured and converted to a mean roughness value in micrometers. In its latest

form the instrument offers extended ranges of clamp pressure and measurement capability,

together with a dual-head option for increased testing efficiency. This versatile instrument

provides the information you need to avoid time-consuming, costly printing problem.

Application

Fine paper, Coated paper, Newsprint, Coated board, Liner board, Films and foils,

Printing/graphics, Packaging and carton board.

Specifications

Single Head Model 58-06-0001

Double Head Model 58-07-00-0001

Number of measuring heads One or Two (58-07-00-0001)

Roughness range-normal 0.20-5.50 um

Air permeance range ISO 5636/1:0-14.5 um Pas

Air permeance range Bedsten equivalent: 0-10000 ml/min

Air permeance range Gurley equivalent: 1-6000s

Clamp pressure-preset 500, 1000, and 2000 kPa

Clamp pressure-custom setting 100-5000 kPa

Alternative Language Options French, German, Spanish, or Finnish

Dimension W x D x H 380 mm x 558 mm 430 mm (15 in x 22 in x 17 in)

476 mm x 558 mm x 430 mm (18.7 in x 22 in x 17 in)

Weight 36 kg (80 lbs)

Electrical 110 VA, 60 Hz, 150 VA or 220 VA, 50 Hz, 150 VA

Air 550-700 kPa (instrument quality)

Standards

ISO 8791/4

Paper and board -- Determination of

roughness/smoothness (air leak method) -- Part 4: Print-

surf method

TAPPI T555 Roughness of paper and paperboard (Print-Surf method)

Testing Instrument having

1. Air supply. A source of clean air, free f oil and water droplets, at a steady pressure within

the range 300 kPa (43 lb/m2) to 600 kPa (86lb/m2). If the instrument is not provided

with internal air filters the provision of an external oil mist filter having an effective

screening of 99.99% at 0.5 mm particle size is recommended.

2. Sensing head. A circular head, consisting of steel lands, which have coplanar, polished

surfaces. The center or measuring land shall be 51.0 µm ± 1.5 µm wide and have an

effective length of 98.0 ± 0.5 mm. The two guard lands shall each be at least 1000 µm

wide at any point and the radial distance between them at any point shall be 152 µm ± 10

µm. The measuring land shall be centered between them to within ± 10 µm. The lands

shall be fixed in an airtight mounting constructed so that air can be passed into the gap

between the inner guard land and the measuring land and exhausted from the gap

between the measuring land and the outer guard land. A spring loaded protective collar

may be fitted outside the guard lands. The measuring head should be readily detachable

for cleaning and so should be constructed in such a way that an airtight seal between the

head and the air inlet and outlet ports may be easily for cleaning and so should be

constructed in such a way that an airtight seal between the head and the air inlet and

outlet ports may be easily formed and maintained. In most commercially available

instruments the back of the head is ground and lapped to mate with an air manifold.

3. Sensing head air pressure regulator. The sensing head shall be supplied with air

regulated at a known differential pressure. In instruments employing variable area

flowmeters and following the original Parker design the differential pressure across the

measuring land and flowmeters is specified as 6.2 ± 0.1 kPa or 19.6 ± 0.1 kPa. Later

instruments employing electronic flow measurement techniques may require different

differential pressure settings and tolerances.

4. Resilient backings. Two types of resilient backings are normally available for use in

pressing at test piece against the sensing head. The backings are in the form of disks, at

least 10 µm greater in diameter than the outside diameter of the guard land.

5. Soft backing. Consist of a rubber offset printing blanket composed of a layer of synthetic

rubber at least 600 µm thick, bonded to a fabric backing giving an overall thickness of at

least 2000 µm ± 200 µm. The apparent hardness of the complete backing is 83 ± 6 IRHD

(International Rubber Hardness Degrees).

6. Hard backing. A composite consisting of a layer of polyester film bonded at its periphery

to cork, offset blanket or similar material. There is a small exhaust hole in the center of

the polyester disk to prevent the entrapment of air between the disk and the cork. The

apparent hardness of the assembly is 95 ± 2 IRHD.

7. Backing holders. Rigid disk, each recessed to accommodate a resilient backing disk. The

design and construction of the holder must be such that the applied clamping pressure is

transmitted to the test piece.

8. Clamping mechanism, allowing clamping of the test piece between the backing and

sensing head during the measurement cycle. The clamping system should allow the

selection of either of the following three clamping pressures; 490 ± 30 kPa, 980 ± 30

kPa, 1960 ± 30 kPa.

9. Measuring system. Any measuring system may be employed which is able to measure

the flow of air between the measuring land and the clamped test piece, convert it to the

“cube root mean cube gap” and display the roughness value in micrometers.

10. Variable area flowmeter instruments. Air leaking between the measuring land and the

test piece is collected and passed through a variable area flowmeter calibrated to read

directly in micrometers roughness. The range of such instrument is normally 0.6-6.0

micrometers and a number of variable area flowmeter, usually four, may be necessary to

cover the range. In the known commercial instrument of this type the flowmeters are

calibrated at a differential pressure of 6.2 ± 0.1 kPa and the pressure across the sensing

must be maintained at this value throughout the test by the measuring air regulator.

11. Impedance type instruments. The design and construction of the Print-surf measuring

head is such that the relationship between differential pressure and airflow, after

correcting for compressibility of air, is substantially linear below some limiting value of

differential pressure. It is therefore possible to calculate the airflow through the head by

comparing the pressure drop across the head with that across a known fluidic impedance

connected in series with it. The differential pressures can be readily measured with

suitable transducer outputs and the impedance value. One advantage of this type of

measuring system is that it is largely independent of measuring air pressure below a

certain limiting value. The measuring system shall make the measurements necessary to

calculate roughness of the test piece 4.5 ± 0.5 s after the application of the clamping

force.

TAPPI T-555 Testing Procedure

1. Carry out the test in the same atmospheric conditions as those used to condit ion the

sample.

2. Ensure that the instrument is located on a rigid horizontal surface free from vibration and

that it is level.

3. Ensure that calibration procedures specified by the manufacturer of the instrument or the

test laboratory have been complied with.

4. Select and fit the backing disk appropriate to the material being tested. In the absence of

specific guidance on backing selection it may be assumed that the hard backing should

be used for papers intended to be printed by the letterpress process. Papers intended to be

printed by other processes, and all boards should be rested using the soft backing.

5. Select the appropriate clamp pressure. The following table gives a guide to selection:

Hard backing, letterpress 1960 ± 30 kPa

Soft backing, letterpress 1960 ± 30 kPa

Soft backing, offset 980 ± 30 kPa

Soft backing, gravure 490 ± 30 kPa

6. Place the test specimens under the sensing head with the side to be tested facing

upwards. Carry out the test in accordance with the instructions given by the instrument

manufacturer. Most electronic type instruments make the measurement and calculate and

display the roughness automatically. If using a variable area flowmeter instrument take

care to select a flowmeter such that the indicated roughness value lies in the upper 80%

of the scale range. Read the top of the float between 3 and 5 s after application of the

clamping force.

7. Repeat step 6 for each of the other test specimens and calculate the arithmetic mean and

standard deviation for the side tested.

8. If result is required for the roughness of the other side of the paper or paperboard, take a

new set of test specimens and repeat steps 6 and 7 for the other side.

SMOOTHNESS OF PAPER

(BEKK METHOD)


This method is for determining the smoothness of individual surfaces of paper when under a

clamping pressure of approximately 100 kN/m2 and using an anvil with an effective area of

10,00 ± 0.05 cm2.

This test is an indirect measure of smoothness when the paper is under moderate pressure. At

other pressures, such as the higher pressure used in some printing presses, the ranking of

papers may be changed, depending upon the relative compressibilities of the papers being

compared. With some papers, radial air leakage may affect the result.

Summary

The specimen is clamped with a pressure of one atmosphere between a plain, circular anvil

having a small hole in its center and soft rubber pad. The time required to draw 10 mL of air

radially between the anvil and the specimen is measured, when a decreasing suction

averaging 49.3 kPa (370 mm of mercury) is applied to the hole.

Testing Instrument

The Automatic Bekk Smoothness Tester is a

micro processer controlled instrument for the

determination of smoothness of paper and board

according to the Bekk Method.

This air leak smoothness test is useful for very

smooth surface, for example, coated label papers,

coated free sheet, or other very smooth papers.

Test result generate with the Bekk tester have

shown excellent correlation with print smoothness

evaluations using offset link. Likewise, Bekk

results have shown good agreement with subjective evaluations of low angle illuminated

surface photomicrographs. Surface integrity is particularly important for printing papers. The

surface fibers must be sufficiently bonded to those beneath the surface and the coating bond

to the fiber matrix must be sound.

An innovative new feature is the Estimate Test Result. It was implemented to save the

operator time when setting up a new test series and choosing the pressure interval and volume

setting but also to save the operator time when doing a quick single test to see what the value

of the paper approximate will be. The ETR value is calculated after the test has been started

(50.55 kPa) based on the rate of rise of pressure. After 10 seconds the ETR value is

displayed. During the test the ETR value constantly re-calculated and updated until the ETR

value at 48.00 kPa is the same as the final test result.

Features:

1. Open throat design enables large samples to be conventiently tested for rapid set-up and

test.

2. Menu-driven software.

3. Air volumes 1/1 and 1/10th volume air receiver speeds up testing for smoother paper.

4. Pressure intervals 50.66-48.00 and 50.66-29.33 kPa.

5. Estimated Test Result: 10 seconds after start of test an ETR value is displayed, this

represent the expected result at test completion.

6. Calibration adjustment using Paper tabs.

7. System check to check if the vacuum system is alright.

8. List statistics on screen.

9. Multi-language standard.

10. RS-232 C serial data output.

11. Porosity Test Option.

12. Applications in Paper, Board.

13. Meets ISO 5627, TAPPI T-479, DIN 53107

Specifications

Model Single Head Model 58-05-00

Estimated Test Result Approx. 10 seconds

Menu Selectable Air volumes, Pressure interval

Data collection RS-232 C serial data output

Display Large black & white liquid crystal graphic high-contrast

Calibrations using Paper tabs

Pressure Interval 50.66-48.00 and 50.66-29.33 kPa

Range 0-99.000

Physical Specification

Dimentions W x D x H 390 mm x 530 mm x 415 mm (15.5 in x 21 in x 16.5 in)

Weight 51 kg (113 lb)

Electrical 110 VAC, 60 Hz, 150 VA or 220 VAC, 50 Hz, 150 VA

Air 600 kPa (instrument quality)

Alternative Language Options French, German, Spanish or Finnish

Standards

ISO 5627 Paper and board – Determination of smoothness (Bekk

method)

TAPPI T-479 Smoothness of Paper (Bekk Method)

DIN 53107 Paper and board roughness/smoothness

Testing instrument having:

1. An anvil with a circular, plain, glass surface, with a small hole (1-2 mm diameter) in its

center, the surface having an effective area of 10.00 ± 0.05 cm2. A capillary connected to

a suction chamber having a volume such that the addition of 10 mL of air at 23°C and

normal pressure causes its negative pressure to fall from 50.7 to 48.0 kPa (380 to 360

mm Hg).

2. A 4-mm-thick pad of soft butyl of EPDM rubber about 50 mm across with smooth

surface and a Shore Durometer hardness of 39 ± 5 units (A scale).

3. A platen (pressure disk) with means of applying a load of 100 ± 5N, including the disk

and rubber pad, to the specimen on the anvil.

4. Stopwatch or timer.


1. Condition of specimens and test them in an atmosphere in accordance with TAPPI T 402

“Standard Conditioning and Testing Atmospheres for Paper, Board, Pulp Headsheet, and

Related Product.” Ensure that the apparatus is not subjected to any vibration during the

test.

2. Set the stopcock of the tester to position “P”. With gentle strokes of the vacuum pump,

raise the mercury column to slightly above 380 mm and turn the stopcock to position

“0”.

3. Place the specimen with the side to be tested in contact with the polished glass surface.

Lay the rubber pad on the paper and on top of this, center the pressure disk.

4. Gently bring the pressure bar down to a horizontal position, with the leveling screw

resting on the depression in the center of the disk. With the aid of the level, and by means

of the leveling screw, bring the pressure bar to level position.

5. After a waiting period of 1 min., during which the paper rapidly compact under the

applied pressure, turn the stopcock to position “M”, and by gently manipulating to the

fine regulating vent at the base of the air chamber, permit the mercury column to drop to

approximately 380 mm. Just before the mercury column reach 380 mm, close the fine

adjustment vent with a firm pushing-turning motion.

6. Various types of stopwatch or timing techniques or devices may be found in various

models of instrument conforming with the method. Visual observation of the drop of the

mercury column with manual timing with the stopwatch is describe in point 6.1. An

electromechanical method utilizing electrodes placed in the capillary column at

appropriate points to active a solenoid which operates the stopwatch is describe in point

6.2. An optical sensing device which detects the dropping of the mercury column past

the appropriate measurement points with its related timing device is describe in point 6.3

6.1 Visual / manual timing. At the instant the 380-mm mark is reached, start the

stopwatch and note the time required in seconds for the mercury column to drop

from 380 to 360 mm.

6.2 Electrode / electromechanical timing. As the mercury column drops past the 380-

mm mark, an electrical circuit is active causing a solenoid to start the stopwatch. As

the mercury column passes the 360-mm mark, an electrical circuit is active and the

solenoid is active to stop the stopwatch.

6.3 Optical / electrical timing. At the instant that the mercury column drops past the

380-mm mark, a light beam/photocell device actives an electrical circuit which starts

an electronic timer. At the instant the mercury column passes the 360-mm mark,

another light beam/photocell device actives an electrical circuit which stop the timer.

6.4 The time referenced in 6.1, 6.2, and 6.3 represents the time necessary for 10 mL of

air to pass between the plain surface and that of the test specimen.

7. Before removing the paper, turn the stopcock back to the “0” position.

8. If the time required for the 20-mm drop is over 300 s, instrument adaptation to change

the cavity size may be used. If the instrumental is equipped with a chamber one-tenth the

standard size, turn the stopcock to the one-tenth position, repeat the test on a separate

specimen, and multiply the observed time by 10. If the instrument is equipped with

chamber changing device, insert either the one-half or one-quarter volume plugs and

repeat the test on separate specimens, multiplying the observed time by either 2 or 4,

respectively.

9. Use a separate specimen for each test, because the pressure on the test specimen slowly

compacts the fibers.

10. Test five specimens each on wire and on the felt sides, respectively.

BURSTING STRENGTH OF PAPER


This method is designed to measure the maximum bursting strength of paper and paper

product having a bursting strength of 50 kPa up to 1200 kPa (7psi up to 175 psi) and in the

form of flat sheets of up to 0.6 mm (0.025 in.) thick. Materials that can be tested using this

method include newsprint, bag paper, fine paper, packaging paper, and printing papers. It is

not intended for use in testing corrugated, fiberboard, linerboard, or hardboards that tend to

cut the thin rubber diaphragm of the bursting tester. For testing paperboard and linerboard,

see TAPPI T 807 “Bursting Strength of Corrugated and Solid Fiberboard”. For tissue testing

see TAPPI T 570 “Resistance to mechanical penetration of sanitary tissue papers (ball burst

procedure)”.

Summary

The test specimen, held between annular clamps, is subjected to an increasing pressure by a

rubber diaphragm, which is expanded by hydraulic pressure at a controlled rate, until the test

specimen ruptures. The maximum pressure reading up to the rupture point is recorded as the

bursting strength.

Significance

Bursting strength is widely use a measure of resistance to rupture in many kinds of paper.

The test is relatively easy and inexpensive to make and appears to simulate some end use

requirements.

Definition

Burst strength of a material is defined as the maximum hydrostatic pressure required to

produce rupture of the material when a controlled and constantly increasing pressure is

applied through a rubber diaphragm to a circular area, 30.5 mm (1.20 in.) diameter. The area

of the material under test is initially flat and held rigidity at the circumference but is free to

bulge during the test.

Testing Instrument

Burst Testers are used as a multi-directional

tensile test to identify failure in the direction of

least resistance for evaluating physical strength

and fiber bond. Models are available to test a

variety of materials. These models can also be

fitted with a device to measure the deflection of

the sample prior to burst. The Burst tester is

designed to meet international standards for

tests on paper, foils, paper boards, corrugated

board, textiles etc.

Feature

Three (3) models to choose from to measure; Paper and film, Board and Corrugated, and

Textiles

Pneumatic sample clamping pressure is measured with a transducer and displayed in

bar/PSI

Compatible with GraphMaster™ PC based data collection and curve analysis software

Date of last calibration stored in memory (clamp pressure, bursting pressure, and height

gauge)

Menus allow programming to meet predefined test methods and international standards

Number of test performed with diaphragm stored in memory

Operation

The Burst Tester is designed for measuring the bursting strength of fabric materials subjected

to an increasing hydrostatic pressure. This pressure is applied to a circular region of the

specimen via an elastic diaphragm. The specimen is firmly held round the edge of this

circular region by a pneumatic clamping device. When the pressure is applied, the specimen

deforms together with the diaphragm. The bursting strength corresponds to the maximum

pressure supported by the specimen before failure. Identical, in the principle to the multi-

directional tensile test, Ball Burst Method for Fabrics, this measurement is independent from

the cutting direction of the sample (machine or cross) since the failure naturally occurs in the

least resistance direction.

The rubber diaphragms with specific thickness and shore hardness must have a bulge versus

pressure pattern within the tolerance of the standards related to the type of material tested.

Applications

Textiles, Fibers, Non-woven’s, Polyester, Fabrics and Felts etc.

Strength, stiffness, dye ability, resilience, fatigue elasticity, orientation and crystallinity.

Meets Standard

ISO 2758, ISO 2759, ISO 1328-2:1999, ISO 2960, ASTM D 3786, ASTM D-774, BS 4768,

TAPPI T403, TAPPI T807, TAPPI T810

Specifications

Model

13-60-00 EC35 13-61-00 EC36 13-62 EC37

Paper and Foils Paper boards and

Corrugated Board Textiles

Measuring Range 40-2000 kPa 0-725 psig (0-5000

kPa) 0-1015 psig

Dimension W x D x H 517 mm x 565 mm x 495 mm (20.35 in x 22.25 in x 19.5 in)

Weight 65 kg (143.3 lbs)

Electrical 110V/60Hz or 220V/50Hz

Air Instrument Quality 600 kPa (6 Bars)

Safety

One start button when safety hood covers the test area and two

start button, which has be pushed simultaneously when cover is up

to have a better view on the test area.

Option Height gauge to measure the height of the burst

Option Printer; small sized and handly roll printer delivers 40 column

tickets

Standards

ISO 2758 Paper. Determination of bursting strength

ISO 2759 Board. Determination of bursting strength

ASTM D 3786 Standard Test Method for Bursting Strength of Textile Fabrics -

Diaphragm Burst Method

ISO 1328-2:1999 Bursting properties of Fabrics

BS 4768 Determination of Bursting Strength and Bursting Distension

TAPPI

TAPPI T403 Bursting Strength of Paper

TAPPI T807 Bursting Strength of Paperboard and Linerboard

TAPPI T810 Bursting Strength of Corrugated and Solid

Fiberboard

Testing Instrument having:

1. A clamp for firmly and uniformly securing the test specimen without slippage during the

test. The clamp shall have two annular, grooved, parallel and preferably stainless steel

surfaces. The clamping forced should be adjustable to accommodate different strength

papers without specimen slippage. The minimum forces should be used to prevent

damage to the specimen under test without specimen slippage.

2. The upper clamping surface (the clamping ring) has a circular opening 30.50 mm (1.2

in.) ± 0.05 mm in diameter. To minimize slippage, the surface which in contrast with the

paper during test has either a continuous spiral or concentric V-grooves in the surface.

The continuous spiral is a 60° V-groove no less than 0.25 mm (0.010 in.) deep with a

pitch of 0.8 mm (1/32 in.). The groove starts 3.2 mm (1/8 in.) ± 0.1mm from the edge of

the circular opening. The concentric grooves are 60° V-grooves no less than 0.25 mm

(0.010 in.) deep and 0.9 mm (1/32 in.) ± 0.1 mm apart. The innermost groove is 3.2 mm

(1/8 in.) ± 1 mm from the edge of the circular opening. The diameter of the upper clamp

should be at least 48 mm.

3. The lower clamping surface (the diaphragm plate) has an opening 33.1 mm (1.302 in.) ±

0.1 mm in diameter. Its surface has a series of concentric 60° V-grooves 0.30 mm (0.012

in.) deep, 0.8 mm (1/32 in.) apart, the center of the first groove being 3.2 mm (1/8 in.)

from the edge of the opening. The thickness of the plate at the opening is 0.66 mm (0.026

in.). The lower edge which is in contact with the rubber diaphragm is rounded to and arc

of 6.4 mm (0.25 in.) radius to prevent cutting of the diaphragm when pressure is applied.

4. The clamping ring is connected to a clamping mechanism through a swivel-type joint or

other means to ensure an even clamping pressure. During test, the circular edges of the

openings in the two clamping plates are required to be concentric to within 0.25 mm

(0.01 in.). Use caution when working around pinch points.

5. A circular diaphragm made of natural or synthetic material. The diaphragm is clamped

between the lower clamping plate and the rest of the apparatus, so that before the

diaphragm is stretched by pressure underneath it, the center of its upper surface is below

the plane of the clamping surface. The pressure required to raise the free surface of the

diaphragm 9 mm (3/8 in.) above the top surface of the diaphragm plate is required to be

30 ± 5 kPa (4.3 ± 0.8 psi). In testing this, a bridge gage may be used, the testing being

carried out with the clamping ring removed. The diaphragm should be inspected

frequently for permanent distortion and if destroyed, replaced.

6. Means of applying controlled, increasing, hydrostatic pressure by a fluid, at the rate of

1.6 mL/s ± 0.1 mL/s to the underside of the diaphragm until the specimen burst.

7. The recommended fluid is USP (96%) glycerin. Purified ethylene glycol (not the

permanent types of radiator antifreeze with additives), silicone, vegetable oil, or other

low viscosity material may be substituted if desired.

8. The bursting resistance of paper increases with increased rate of loading. The rate of

strain must be maintained effectively constant to obtain reproducible results. Any air

present in the hydraulic system of the tester will lower the rate of distortion of the

specimen and must be substantially removed. Air is more commonly trapped under the

rubber diaphragm and in the tube of the gages.

9. A maximum-reading pressure gage of the Bourdon type, of appropriate capacity and with

a graduated circular scale 95 mm ( 3 ¾ in.) or more in diameter. Bourdon gauge should

have an accuracy of ±0.5% of the final scale value. The Bourdon gage should have an

accuracy of ±1% of reading.

10. The expansibility of a gage is a volume of liquid entering the gage tube per unit increase

in pressure, when air is absent. The gage expansibility must be within 15% of the

specified value.

11. To avoid overloading and possible damage to the gage, a preliminary bursting test should

be made with a high-capacity gage.

12. Pressure sensitive electronic gages are today widely replacing the Bourdon type gages.

The pressure transducer should be have an accuracy of ±0.2% of final scale value. The

advantages is that one sensor normally can handle the entire measuring range.

13. The pressure transducers must have at least an accuracy of 1% of measurement or ±10

kPa (1.5 psi) which ever provides the greater accuracy.

14. To avoid overloading and possibly damaging the transducer, a preliminary bursting test

should be made with a high-capacity transducer.


1. Clamp a specimen securely in position, overlapping the specimen at all the points. Apply

the hydrostatic pressure as specified until the specimen ruptures, and record the

maximum pressure registered. Watch carefully for any movement of the unclamped

margin of the specimen. If slippage is indicated, discard the test and increase the

clamping pressure. Ifit appears that excessive clamping pressure damage the specimen,

discard the test and reduce the clamping pressure.

2. After each test return the pressure indicator gently to zero.

3. Make ten test on each side of the paper.

TENSILE PROPERTIES OF PAPER AND PAPERBOARD

(USING CONSTANT RATE OF ELONGATION APPARATUS)


This test method describes the procedures, using constant-rate-of-elongation equipment, for

determining four tensile breaking properties of paper and paperboard: tensile strength,

stretch, tensile energy absorption, and tensile stiffness.

This procedure is applicable to all types of paper and paperboard within the limitations of the

instruments used, whether the instruments perform horizontal or vertical tests or whether they

are manually operated or computer controlled. It is also applicable to handsheets, with

modifications, as specified in TAPPI T 220 “Physical Testing of Pulp Handsheet”. It does not

apply to combined corrugated board.

Definitions

1. Tensile strength, the maximum tensile force developed in a test specimen before rupture

on a tensile test carried to rupture under prescribed conditions. Tensile strength (as used

here) is the force per unit width of test specimen.

2. Stretch, the maximum tensile strain developed in the test specimen before rupture in a

tensile test carried to rupture under prescribed conditions. The stretch (or percentage

elongation) is expressed as a percentage, i.e., one hundred times the ratio of the increase

in length of the test specimen to the original test span.

3. Tensile Energy Absorption (TEA), the work done when a specimen is stressed to rupture

in tension under prescribed conditions as measured by the integral of the tensile strength

over the range of tensile strain from zero to maximum strain. The TEA is expressed as

energy per unit area (test span × width) of test specimen.

4. Tensile stiffness, the ratio of tensile force per unit width to tensile strain within the elastic

region of the tensile-strain relationship. The elastic region of the tensile-strain

relationship is the linear portion of the load-elongation relationship up to the elastic limit.

The elastic limit is the maximum tensile force above which the load-elongation

relationship departs from linearity. (Tensile stiffness is numerically equivalent to E • t,

where E is the modulus of elasticity and t is sample thickness.)

5. Breaking length, the calculated limiting length of a strip of uniform width, beyond

which, if such a strip were suspended by one end, it would break of its own weight.

6. Tensile index, the tensile strength in N/m divided by grammage.

Significance

1. Tensile strength is indicative of the strength derived from factors such as fiber strength,

fiber length, and bonding. It may be used to deduce information about these factors,

especially when used as a tensile strength index. For quality control purpose, tensile

strength has been used as an indication of the serviceability of many papers which are

subjected to a simple and direct tensile stress. Tensile strength can also be used as an

indication of the potential resistance to web breaking of papers such as printing papers

during printing on web fed press or the web fed converting operations. When evaluating

the tensile strength, the stretch and the tensile energy absorption for these parameters can

be of equal or grater importance in predicting the performance of paper, especially when

that paper is subjected to an uneven stress such as gummed tape, or a dynamic stress

such as when a sack full or granular material is dropped

2. Stretch (sometimes evaluated in conjunction with bending resistance) is indicative of the

ability of paper to conform to a desired contour, or to survive nonuniform tensile stress.

It should be considered important in all papers, but is of particular importance in papers

where stress-strain properties are being modified or controlled. This includes creped

paper, pleated paper, air-dried paper, and paper that has been made extensible through

mechanical compaction. Stretch may be used as an indication of the amount of crepe in

tissues, towels, napkins, and similar grades. Stretch is evaluated in decorative papers and

certain industrial grades such as paper tapes and packaging papers, both as an index of

how well the paper will conform in irregular shapes and, long with tensile energy

absorption, as an indication of the paper’s performance under conditions of either

dynamic or repetitive straining and stressing. Stretch has also been found important in

reducing the frequency of breaks on high-speed web fed printing presses such as are used

to print newspaper.

3. Tensile energy absorption is a measure of the ability of paper to absorb energy (at the

strain rate of the test instrument), and indicates the durability of paper when subjected to

either a repetitive or dynamic stressing or straining. Tensile energy absorption expresses

the “toughness” of the sheet. An example of this is a multi-wall sack that is subject to

frequent dropping. In packaging applications such as multi-wall sacks, favorable drop

test and low failure rates have been found to correlate better with tensile energy

absorption than with tensile strength.

4. Tensile stiffness tell of the stiffness of the sheet and often gives a better indication of the

mechanical response of the sheet to converting forces than does failure criteria.

Testing Instrument

The instrument has a small footprint just over

0.20 square meters (2.3 square feet). The

model 84-76 provides a large 5.7 inch color

display, intuitive operator interface, software

control, integrated printer & serial port for data

collection.

The new unit is designed to test strength of

sheet materials including Paper, Board, Tissue

Paper, Film Packaging Seals, Adhesives,

Pressure Sensitive Tapes and variety of low

force tensile applications up to 1330 N (136

Kg, 300 lbs).

The Model 84-76 Tensile Tester is a roboust, precision, tensile strength instrument suitable

for rugged production environments yet designed to provide highly accurate measurements

for research applications.

Features

1. Load Capacity 1330 N (300 Lb)

2. Air-Operated Clamps for sample widths of 25, 50 or 75 mm (1.2 & 3 inch).

3. Load Cell selection 1330, 444 & 111 N (300, 100 & 25 lbs).

4. Travel stroke 300 mm (12 inches) or 914 mm (36 inches).

5. Force unit – Newtons, Kilograms and Pounds.

6. Distance unit conversion: Milimeters and Inches.

7. Large high contrast 5.7 inch color display for result and statistics.

8. Statistics include Average, Minimum, Maximum, COV and SD

9. RS232 serial output and built-in printer included.

10. Compatible with GraphMasterTM

PC based data collection and curve analysis software.

Application

1. Paper

2. Board

3. Tissue Paper

4. Adhesives

5. Peel Testing

6. Seal Strength

7. 180 Peel Strength

8. Bond Strength

Specification

Model 84-76-00-0001

Ranges

Measuring Range Load Capacity 1330 N (300 lb)

Load Cells 1330, 444 & 111 N (300, 100 & 25 lbs)

Accuracy ±5% of reading

Specimen Width up to 76 mm (3 inches)

Speed

Test Speed 5-300 mm/minute (2-12 inch/min)

Return Speed 5-300 mm/minute (2-12 inch/min)

Stroke length 300 mm (12 inches), or 914 mm (36 inches)

Force Units Newtons, Kilograms and Pounds

Distance Unit Conversion Milimeters and Inches

Statistic Display

Number of test

Highest value

Lowest value

Average

Standard deviation

Variation coefficient

Max number of test: 100

Machine Requirement

Power 120 V/220 V 50Hz/60 Hz

Safety Features

Overload protection electronically at 100% of measuring rage

during test

Overload protection during travel

Connections RS232C serial output, Built-in printer, GraphMaster

compatible

Internal Language English – Dutch – German – French – Spanish – Finnish –

Italian

Physical Specification

W x D x H 53 cm x 40 cm x 79 cm (21 in x 16 in x 31 in)

Weight 43 kg (95 lbs)

Standards

ISO 12625-4 Tissue Paper and Tissue Products-Part 4: Determination of

tensile strength, stretch at break and tensile energy absorption.

TAPPI T-494 Tensile properties of paper and paperboard (using constant

rate of elongation apparatus).

ISO 1924 Paper and Board – Determination of tensile properties – Part

3: Constant rate of elongation method (100 mm/min).

CPPA D34 Tensile Breaking Properties of Paper and Paper Board.

ASTM Standard Test Method for Seal Strength of Flexible Barrier

Materials.


1. Two clamping jaws, each with a line contact for gripping the specimen, with the line of

contact perpendicular to the direction of the applied load and with means for controlling

and adjusting the clamping pressure.

2. The clamping surfaces of the two jaws shall be in the same plan and so aligned that they

hold the test specimen in that plane throughout the test. The clamping lines shall be

parallel to each other within an angle of ± 1°, and shall not change more than 0.5° during

the test. The applied tensile force shall be perpendicular to the clamp lines within ±1°

throughout the test.

3. The distance between line contacts at the start of the test shall be adjustable and

resettable to ±0.5 mm (nominally 0.02 inch) for the specified initial test span.

4. The rate of separation of jaws shall be 25±5 mm/min (nominally 1.0 inch/min), or as

otherwise noted and once set shall be resettable and constant to ± 4%.

5. Recorder on indicator capable or indicting the actual force on the specimen within 1% or

0.1 N, whichever is greater.

6. Recorder speed or indicator shall be adjustable to provide a readability and accuracy of

±0.05% stretch.

7. Alignment jig to facilitate centering and aligning the specimen in the jaws, so that the

clamping lines of contact are perpendicular to the direction of the applied force and the

center line (long dimension) of the specimen coincides with the direction of applied

force.

8. Planimeter or integrator, respectively, to measure the area beneath the load-elongation

curve or to compute directly the work to rupture, with an accuracy of ±1%.

9. Specimen Cutter, for cutting specimens of the required width, with straight parallel sides.

10. Magnifier and scale or optical comparator, capable of measuring the specimen width to

the nearest 0.1 mm (0.004 in.).

TAPPI T-494 Testing Procedures

1. Perform the test in the testing atmosphere specified in T 402.

2. If the test specimen width is not known to 0.1 mm (nominally 0.004 in) (i.e., if a

previously evaluated precision cutter is not used), determine width and parallelism using

magnifier and scale. Lack of parallelism is indicated by a difference in width of the two

ends of specimen.

3. The testing machine shall be calibrated and adjusted as described in Appendixes A.1 and

A.2.

4. Set the clamps to an initial test span (distance between line contacts) of 180 ± 5 mm

(nominally 7.0 in.). determine and always reset this distance within ± 5 mm (nominally

0.002 in).

5. Set the controls for rate of separation of the jaws to 25 ± 5 mm/min (nominally 1.0

in.min). in cases where the time required to break a single strip exceeds 30 s, a more

rapid rate of jaw separation shall be used, such that the time to break a single strip will be

between 15 and 30 s. in such cases the reported, along with the test data.

6. Select recorder speed or indicator to give a readability equivalent to 0.05% stretch.

7. Select the full-scale reading, if possible, so that breaking force can be read in the upper

three-fourths of the scale. Make preliminary trial tests if necessary to determine full-scale

load.

8. Align and clamp the specimen firs in one jaw and then, after carefully removing any

noticeable slack, but without straining the specimen, in the second jaw. While handling

the test specimen, avoid touching the test area between the jaws with the fingers. Use a

clamping pressure determine to be satisfactory, so that neither slippage nor demage to the

specimen occurs. Automated instrument for which both jaw close simultaneously are

within the context of this method.

9. Test 10 specimens in each principal direction for each test unit.

10. Reject any value in which the test specimen slips in the jaws, break within the clamping

area, or shows evidence of uneven stretching across its width. Also reject any values for

test specimens which break within 5 mm of the more than 20% of the specimens for a

given sample are rejected, reject all readings obtained for that sample, inspect the

apparatus for conformance with specifications, and take any steps necessary to correct

the trouble.

11. If determine tensile strength and stretch, read and record the breaking force to 0.5% of

full scale and the elongation at break to the equivalent of 0.05% stretch.

12. Determine tensile energy absorption, record the integrator reading or use the planimeter

to determine the area under the load-elongation curve from zero load to the breaking

load.

13. If determine tensile stiffness, measure the strain at two force levels within the elastic

region of the tensile force-strain relationship. The lower of the force levels must be least

5 % of the apparent elastic limit, the higher not more than 75%, and the two force levels

must be separated by least 20% of the apparent elastic limit. For purposes of this

measurement, the apparent elastic limit is defined as the point at which the tensile force-

strain relationship departs from linearity. Alternately, the slope can be continuously

monitored, and the maximum value taken as the measure of tensile stiffness. Determine

the tensile stiffness, S, from:

St = (Δf • L) / (w • ΔL)

where:

St = Tensile stiffness, kN/m

Δf = difference between two force levels, kN

L = initial test length, m

w = initial specimen width, m

ΔL = change in length corresponding to Δf, m

INTERNAL TEARING STRENGTH OF PAPER

(ELMENDORF TYPE-METHOD)


This method measures the force perpendicular to the plane of the paper required to tear

multiple plies through a specified distance after the tear has been started using an Elmendorf-

type tearing tester. It does not measure edge-tear resistance. The measured results may be

used to calculate the approximate tearing resistance of a single sheet. It is not suitable for

single-ply tear testing.

For highly directional boards and papers, prepare specimens according to T 496 “Specimen

Preparation for Cross Directional Internal Tearing Resistance for Paper, Paperboard and

Related Materials”.

Caution is recommended in interpreting results from weakly bonded sheets, especially those

containing lightly refined long-fibered chemical pulps. The low rate of tear when multiple

plies are torn simultaneously may produce erroneously high results.

Summary

Multiple sheets of the sample material are torn together through a fixed distance by means of

the pendulum of an Elmendorf-type tearing tester. The work done in tearing is measured by

the loss in potential energy of the pendulum. The instrument scale is calibrated to indicate the

average force exerted when a certain number of plies are torn together (work done divided by

the total distance torn).

Significant

1. Several elmendorf-type tearing testers are available and in use throughout the world,

principally those of Australian, British, German, Swedish, and United States

manufacture. In addition, testing practices also vary, as is reflected in the related methods

for these countries or others listed. Instruments and practices in use vary in at least three

major respects :

a. The first difference is in the design of the pendulum sector. Instruments conforming to

the requirements specified under section 4 have a deep cutout in the pendulum sector

to prevent friction between the specimen and the pendulum. The oldest model,

without the deep cutout, permitted the specimen to come in contact with the sector

during the test and gave values, which have been observed to be as much as 10%,

varies as a function of instrument and different types and grammages of paper.

b. The second difference is in the design of the specimen clamps which, together with

the structural characteristics of the paper which govern the nature of the tear with

respect to its splitting tendencies during the test, can have an appreciable influence on

the mode of tearing and may result in significant differences. The clamps designs used

by some manufactures may vary even for their own models. Instruments are available

with pneumatically activated grips; their use minimizes variations due to differences

in clamping pressures exerted by manually tightened grips.

c. The third difference results from a combined variation in testers and testing practices.

As measured tearing resistance increases or decreases for different types of paper, it

may become so large or so small as to be outside the practical range of the instrument.

This problem may be overcome by changing the number of plies tested at one time.

The tearing length must never be varied in an effort to alter the pendulum capacity.

2. The foregoing, together with other lesser difference in design details between

instruments or testing practices, preclude specifying a tearing instrument and method that

would give essentially the same test results when using Elmendorf instruments of

differently design and manufacture. Even for one specific model, some procedural

variables such as the number of plies torn may alter the test values calculated on a single

sheet basis substantially.

Testing Instrument

The TMI Elmendorf Tear Tester is internationally recognized as a basic instrument for

performing one of the most important tests in quality evaluation. It is used to measure tear

resistance of many sheet materials, including: paper, board, textiles, non-wovens, films, foils,

and coated materials.

The instrument provides reading accuracy of ±1% of

the indicated reading when use with the standard

1600g pendulum. The interchangeable pendulums

available are as follows:

Pendulum

83-10-01 extra light 200 g 19.0 gcm

83-10-02 light 800 g 68.8 gcm

83-10-03 medium 1600 g 137.6 gcm

83-10-04 heavy 3200 g 275.2 gcm

83-10-05 extra heavy 6400 g 550.4 gcm

Applications

Paper, Foil, Film, Textiles, Nonwovens

Specifications

Model :83-10-00

Weight : 2.25 kg (10 lbs)

Dimensions W x D x H : 35.6 cm x 24 cm x 30.4 cm (14 in x 9.5 in x 12 in)

Standards

Conforms to TAPPI T-414, ASTM D1922, ISO 1974, as well as CPPA, APPITA, and SCAN

standards.

Options

Precision calibration check weights (15 to 2130g), set of 7 weights.

Pneumatic grips (requires min. 60 psi.)


1. Elmendorf tearing tester, with cutout which prevents the specimen from coming in

contact with the pendulum sector during the test, and having the following elements:

a. A stationary clamp; a movable clamp carried on a pendulum formed by a sector of a

circle free to swing on a ball bearing; a knife mounted on a stationary post for starting

the tear; means for leveling the instrument; means for hokling the pendulum in a

raised position and for releasing instantaneously; and means for registering the

maximum are through which the pendulum swings when released.

b. The registering means may consist of a graduated scale mounted on the pendulum, a

pointer mounted on the same axis as the pendulum with constant friction just

sufficient to stop the pointer at the highest point reached by the swing of the sector,

and an adjustable pointer stop for setting the zero of the instrument.

c. The pointer and scale may be replaced by a digital readout unit which gives readings

of equivalent accuracy and precision.

d. With the pendulum in its initial position ready for a test, the clamps are separated by

an interval of 2.8 ± 0.3 mm and are so aligned that the specimen clamped in them lies

in a plane parallel to the axis of the pendulum, the plane making an angle of 27.5 ±

0.5˚ with the perpendicular line joining the axis and the horizontal line formed by the

top edges of the clamping jaws. The distance between the axis and the top edges of

the clamping jaws is 102.7 ± 0.1 mm. The clamping surface in each jaw is at least 25

mm wide and 15.9 ± 0.1 mm deep.

e. The instrument measures the energy (work done) used by the pendulum in tearing the

test specimen. To convert to average tearing force, the energy is divided by the total

distance through which the force is applied. This division may be accomplished by the

electronic in digital red-out instruments so that the read-out is directly in grams-force

or in millinewtowns (SI unit of force). For pointer and scale instruments, the scale

may be in millinewtowns or in grams-force for a specified number of plies; i.e., when

the specified number of plies are torn together, the scale reading gives the average

resistance (force) of a single ply.

f. Instruments of several capacities e.g., about 2000, 4000, 8000, 16.000, 32.000 mn

(200, 400, 800, 1600, 3200 gf) and perhaps others are available, with the several

capacities being by individual instruments, interchangeable pendulum sectors, or

augmenting weights. The instrument recognized as “standard” for this method has a

capacity of 1600 gf (SI equivalent 15.7 N); i.e., it has a pendulum sector of such mass

distribution that its 0 to 100 scale is a direct reading in grams-force per ply when 16

plies are torn together. For a 16-ply test specimen, the tearing distance K = 16 x 4.3

cm (tearing distance per ply) x 2 = 137.6 cm, the factor 2 being included since in

tearing a given length the forces is applied twice the distance. Likewise, for 16-ply

test specimen, the tearing energy per ply for a scale reading of 100 would then be 100

gf x 137.6 cm or 13760 gf cm (SI equivalent 1349.4 Mj). For some of the instruments

of different capacities where different numbers of plies are required, or when the

number of plies tested using the “standard” instrument differs from 16, different

values of K and/or the tearing energy per ply may be calculated, using the above

calculation as a model.

g. In the “standard’ instrument, the zero reading on the scale is at about 70˚ from the

center line (i.e., the vertical balance line when the pendulum hangs freely), the 100

reading is at about 21˚ from the center line, and a vertical force of 1057.3 ± 2.0 gf (SI

equivalent 10.369 ± 0.020 N) applied at 22.000 ± 0.005 cm from the pendulum axis is

required to hold the pendulum sector at 90˚ from its freely hanging position to give a

total capacity at 1600 gf ± 6.4 gf.

h. The cutting knife for the test specimen is centered between the clamps and adjusted in

height so that the tearing distance is 43.0 ± 0.2 mm; i.e., the distance between the end

of the slit made by the knife and the upper edge of the specimen is 43.0 ± 0.2 mm

when the lower edge of the 63.0 mm wide specimen rests against the bottom of the

clamp.

2. Specimen cutter. To insure parallel specimens 63.0 ± 0.15 mm wide with sharp and clean

edges, it is desirable to use the type having two hardened and ground base shears, twin

knives tensioned against the base shears, and a hold-down mechanism.


1. Precondition, condition, and test the specimens in accordance with TAPPI T-402

“Standard Conditioning and Testing Atmosphere for Paper, Board, Pulp Handsheets, and

Related Products”.

2. Raise the pendulum sector to its position and set the pointer against its stop. Center the

specimen in the clamps with the bottom edge carefully set against the stops. Securely

clamp the specimen using approximately the same pressure on both clamps. Make the

initial knife cut. Depress the pendulum stop quickly as far as it will go to release the

pendulum. Hold down the stop until after the tear is completed and catch the pendulum

on the return swing without disturbing the position of the pointer.

3. Make only one test per specimen, each specimen consisting of the same number of plies.

Make tests alternately with the wire side of all the plies of a specimen facing the

pendulum and with the wire sides of all the plies away from the pendulum. Make certain

that the specimen leans toward and not away from the pendulum by gently bending the

specimen at the clamp if necessary ,but in doing so avoid affecting the moisture content

of the test area.

4. Record the scale readings to the nearest half division; also record the number of plies

used in the specimen.

5. If the sheets split extensively when being torn, report this. If the line of tear fails to pass

through the top edge of the specimen but deviates to one side, note and report this, but do

not use the reading so obtained. If more than one-third of the tests exhibit this behavior,

this method should not be used for the material concerned. Preparing the test specimens

according to T-496 “Specimen Preparation for Cross Directional Internal Tearing

Resistance for Paper, Paperboard and Related Materials” may alleviate this problem.

6. Calculate the average tearing force in milinewtons and, if desired, in grams-force

required to tear a single play as follows:

a. For the standard 1600-gf instrument with 0-100 scale:

Average tearing force, mN = (16 x 9.81 x average scale reading) / number of plies

Average tearing force, gf = (16 x average scale reading) / number of plies

b. If an instrument has an SI metric scale (e.g., 0-1000 graduations)

Average tearing force, mN = (16 x avg. scale reading x capacity, N) / (number of

plies x 15.7 N)

Average tearing force, gf = (16 x avg. scale reading x capacity, N) / (9.81 X

number of plies x 15.7 N)

c. If an instrument has a direct-reading scale (e.g., digital read-out) that directly gives the

force per ply when preset for the number of plies:

Average tearing force, mN = scale reading if directly in milinewtons, or

= 9.81 x scale reading if in grams-force

Average tearing force, gf = scale reading / 9.81, if scale is in milinewtons, or

= scale reading if directly in grams-force

ABRASION LOSS OF PAPER AND PAPERBOARD OF PAPER

(WAX PICK TEST)


This method, applicable to uncoated and coated papers, is designed to measure the surface

strength of paper or its resistance to picking. It is not applicable to loosely felted papers such

as blotters or roofing felts nor to some coated papers containing thermoplastic resins in the

coating adhesive.

Summary

In this test, calibrated sealing waxes with increasing adhesive power are pulled from the

surface of the specimen. The highest number of the wax in the series which does not distrub

the surface of paper is the numerical rating of the pick.

Significance

1. Many printing and converting operations require the surface of the paper to have

sufficient z-direction strength to give satisfactory result. Since no absolute values are

obtained with this method, test result should be correlated with actual performance of the

material during the subsequent coating, converting, printing or packaging operation.

2. For coated paper, where a significant portion of the casein or starch coating adhesive has

been replaced with a thermoplastic resin, this is very little, if any, correlation between

printing press performance and wax test result. The molten wax forms a stronger bond

with the coating containing thermoplastic resin and the resulting pick causes the paper to

appear weak, when in fact it is not.

3. For these sheets containing latex and similar substances, a more direct method

employing the actual medium to be applied is recommended.

Definitions

1. Pick, a pick occurs when the surface of the paper specimen blisters, breaks, or lifts and or

paper or coating substance adheres to the surface of the wax.

2. Critical wax strength number, the average highest numerical designation of the wax that

does not disturb the surface of the paper.

Testing Instrument

Dennison type Wax Pick Testing is for the

evaluation of surface strength on the paper

and paperboard. Waxes are heated and

applied to the surface of the sheet. After

cooling, they are pulled from the surface

and wax stick is checked to see if it has

pulled fiber or coating from the surface.

The highest value wax which does not

rupture the surface is reported as the pick

strength of the sheet.

This traditional test has been used for many years and is well known in all parts of the world.

It is simple, easy to use, and inexpensive.

Applicable standards: TAPPI T-459

For testing in accordance with TAPPI method T-459

Application

The integrity of a paper or board surface depends both on the characteristics of the fiber

matrix and those of the applied coating. The fibers must be as evenly distributed as possible,

be “keyed” into the sheet with sufficient bonding to adjacent fibers and have liquid

absorption properties to give the correct “bleed” into the sheet of the coating adhesive or

binder and the water dispersant.

The coating must have the correct ratio of pigment and binder to correlate both with the base

paper quality to ensure strong adhesion, also to give the desired “finish” to the product. The

degree of adhesion and hence surface integrity maintained under condition imposed by

subsequent drying, calendaring and printing operations is widely measure with Dennison

waxes.


1. Heating device, such as: Bunsen burner, alcohol lamp, propance torch, or electric heat

element.

2. Wooden block, about 90x40x10 mm having a 30 mm diameter hole with an edge about 3

mm from one end.

3. Work surface that is smooth, hard, and a poor conductor of heat, such as wood, (Glass,

metal, or artificially cooled surface are unsuitable).


1. Precondition, condition, and test the specimens in an atmosphere in accordance with

TAPPI T 402.

2. Place a test specimen on the work surface. Select wax sticks estimated to have less

adhesiveness than will disturb the surface of the specimen. Clean the end with a sharp

blade or if necessary by melting off any paper or coating residue.

3. Heat the end in a low flame or by electrical heat element, rotating the sticks slowly

between the thumb and finger until several drops of melted wax have fallen, but do not

let the sticks catch fire. Also the molten wax should not “bubble” which indicates wax is

too hot. The entire surface-should be molten wax.

4. Quickly place the melted end of the wax sticks on the surface of the paper specimen with

film, but not undue, pressure so that the end spreads out to about 20mm diameter, and

with draw the fingers immediately, allowing the wax sticks to stand vertically on the

paper.

5. Allow the wax to cool for at least 15 min and not more than 30 min. Place the wooden

block with the hole over the vertical stick of wax so that the stick protrudes through the

hole, press the block down firmly with one hand to prevent the paper from wrinkling or

tearing, and with the other pull the wax from the sheet with a quick jerk at right angles to

the paper surface.

6. Examine both the tip of the wax and the paper specimen under normal reading

illumination with no magnification. There must be definite indication of fibers or coating

disturbed to called a pick or surface rupture.

7. If the surface is not ruptured, repeat the test, using the same specimen with wax or

ascending numerical order until the surface of paper specimen blisters, breaks, picks or

lifts. Test a minimum of five specimen on their wire side and five other specimen on

their top side, or if not identifiable as such, five each from the two different sides of the

paper.

8. Record the highest numerical designation of the wax that does not disturb the surface of

the paper and average the result on each side to the nearest wax number.

Caution: wax is hot and will burn skin if molten wax comes in contact with hands.

AIR RESISTANCE OF PAPER

(GURLEY METHOD)


This method is used to measure the air resistance of approximately 6.45 sq. cm. (1 sq. in.)

circular area of paper using a pressure differential of 1.22 kPa. The recommended range of

the liquid column instrument is from 5 to 1800 second per 100 mL cylinder displacement. For

more impermeable paper the time requirements become so excessive that order techniques

are preferable.

This method measures the volume of air that passes through the test specimen, along with any

possible leakage of air across the surface; therefore it is unsuitable for rough-surface papers

which cannot be securely clamped so as to avoid significant surface and edge leakage.

For a similar method of measuring air resistance that tests paper at a higher pressure (approx.

3 kPa), and has higher resolution in measuring smaller air volumes, refer to TAPPI T-536.

For a method of measuring air permeance at pressures up to 9.85 kPa, using both smaller and

larger test areas, refer to TAPPI T-547.

Summary

This method measures the amount of time required for a certain volume of air to pass through

a test specimen. The air pressure is generated by a gravity-loaded cylinder that captures an air

volume within a chamber using a liquid seal. This pressurized volume of air is directed to the

clamping gasket ring, which holds the test specimen. Air that passes through the paper

specimen escapes to atmosphere through holes in the downstream clamping plate.

Significance

The air resistance of paper may be used as an indirect indicator of Z-directional fluid

permeance, as well as other variables such as: degree of refining, absorbency (penetration of

oil, water, etc.), apparent specific gravity, and filtering efficiency for liquid or gases. Air

resistance is influenced by the internal structure and also the surface finish of the paper.

Internal structure is controlled largely by the type and length of fibers, degree of hydration,

orientation, and compaction of the fibers; as well as the type and amount of fillers and sizing.

The measurement of air resistance is a useful control test for machine production; but due to

the number and complexity of factor outlined above; careful judgement should be used in the

specification limits for air resistance.

Definition

Air resistance is the resistance to the passage of air, offered by the paper structure, when a

pressure difference exists across the boundaries of the specimen. It is quantified by obtaining

the time for a given volume of air to flow through a specimen of given dimensions under a

specified pressure, pressure difference, temperature, and relative humidity.

Testing Instrument

Densometer, model 58-03 measures air permeability

(Gurley type) of sheet like materials including Paper,

Paperboard and nonwovens. Porosity of paper or

density is an important measurement when simulating

conditions where paper is picked up under vacuum.

Air resistance by the Gurley method measures the

amount of time in seconds for a specific volume of

air to pass through the voids in a sheet of paper under

a specified clamping pressure.

Application

Liner, Paper, Tissue, Printing

Instrument Size

D x H x W: 254 mm X 508 X 254 mm

(10 x 20 x 10 in.)

Weight: 22.6 kg (39 lbs)

Connection

Electrical: Specify voltage requirements when ordering

Standards

Meets TAPPI T460, ASTM D725, D726, D202, ISO 5636/5, BS 5926, CPPA D.14, SCAN

P19, and AS/NZ 1301.420

Features

• Built-in leveling base

• Built in automatic digital timer

• RS-232 output

• User-selectable measuring volume

• Standard 1” orifice

• 20 ounce cylinder

• Factory installed smoothness arm ready for

Optional Smoothness/Softness kit.


1. Place the instrument on a level surface, free of vibrations, so that the outer cylinder is

vertical. Fill the outer cylinder with sealing fluid to a depth of about 125 mm, as

indicated by a ring on the inner surface of the cylinder or to a depth specified by the

instrument manufacturer.

2. Raise the inner cylinder before inserting the specimen in the test clamp until its rim is

supported by the catch. Clamp the specimen between the clamping plates. Some versions

use a hand-tightened capstan (jackscrew), while other versions are equipped with an

eccentric cam lifting mechanism. Since the capstan version has no measurement or

control of the clamping force, tighten with care in order to ensure proper specimen

sealing. Over tightening, as well as under tightening, can cause erroneous results.

Excessive clamping force may overstress the structural parts of the instrument and affect

the parallel alignment of the upper and lower gasket surfaces. The eccentric cam lifting

mechanism is actuated by turning one of the two knobs to the left or to the right of the

lifting assembly. This self-locking design decreases the potential of using excessive

clamping force. After the specimen is properly clamped, gently lower the inner cylinder

until it floats.

3. As the inner cylinder moves steadily downward, measure the number of seconds, to the

nearest 0.1 s, required for the inner cylinder to descend from the 150 mL mark to the 250

mL mark, referenced to the rim of the outer cylinder.

4. Refer to Table 1 and Table 2 for the appropriate correction factors if displacement

intervals other than the 150 to 250 mL marks are used. Multiply the measured time by

the correction factors from the appropriate table to obtain a corrected result for the

alternate interval. It may be expedient to use shorter intervals for relatively impervious

papers, and longer intervals for more porous papers. Also, instruments that use electronic

timing devices may be adjusted to use different intervals. If the correction factors are not

used, the percentage error related to the measurement interval can be determined from

the data in the tables.

5. Refer to manufacturer’s instructions for calibration and measurement procedures.

6. Test five specimens with the top side up, and test five specimens with the top side down.

BENDING RESISTANCE OF PAPER AND PAPERBOARD BY SINGLE-POINT

BENDING METHODS


This procedure is used to measure the bending resistance of paper and paperboard in the

machine directions, by determining the bending resistance in mN of a 38 mm (1.5 in.) wide

vertically clamped sample, at 15° or 7.5° deflection. For this method the standard bending

angle is 15 ± 0.1°. For specimens that break or are otherwise unsuitable at 15° a bending

angle of 7.5 ± 0.1° shall be used.

Definitions

1. Bending resistance, the resistance offered to a bending force by a rectangular specimen,

which is clamped along one side, measured under specified conditions. The bending

resistance is considered to be measured towards the side (felt or wire) that is concave

during bending. Bending resistance is commonly referred to as “stiffness”, however, this

is incorrect for the engineering meaning of the wording.

2. Machine direction bending resistance, the bending resistance of a specimen, clamped

with its machine direction perpendicular to the line of clamping.

3. Cross direction bending resistance, the bending resistance of a specimen, clamped with

its cross direction perpendicular to the line of clamping.

Testing Instrument

Model 79-25 is a user-friendly microprocessor

controlled instrument to determine the bending

resistance of paper, paperboard, plastic film,

medical tubing, and wire. Bending stiffness is a

characteristic associated with the rigidity of a

material. This property is related to the modulus

of elasticity of the material’s stiffness.

What makes our Bending Resistance instrument so unique is its versatility and accuracy.

Bending forces are measured at selectable bending angles from 5.0 to 90°. The instrument is

available with a 100 or 1000 gram precision load cell. The advanced data acquisition system

senses forces down to 0.5g. Materials can range from 5 to 50mm in length, up to 2.5mm

thick.

Operation Details

The Bending Resistance Tester is an important property designed to determine the force

required to deflect a material through a defined angle at a defined bending length. The testing

sequence is completely automatic. When the pneumatic clamp is closed the clamp begins to

turn at a slow speed until the sample contacts the load cell and a positive force is recorded. At

this point, the instrument zeros the measuring electronics and starts to record force, angle and

time. The test clamp turns at 5 degrees per second to the selected angle and then returns to the

home position. Immediately after the test is finished, the peak angle is displayed and the

pneumatic clamp will open. Optional GraphMaster software will also record force, angle and

time has the capability to provide a real-time test curve during the measurement for additional

analysis and review.

Specification

Model 79-25-00 Series

Measuring units Mn, Nmm, Taber

Ranges 0-1000 mN or 0-10 mN

Min. force sensitivity 0.5mN with 1000mN load cell

Accuracy ±1%

Specimen Width Bend Angle Up to 38 mm, 4 mm opening 5.0 – 90.0 degrees

(selectable in 0.1 steps)

Accuracy ± 0.1 degree

Speed 5º/second

Bending length Motorized setting with 6 automatic stops

Bending positions 5mm - 10mm - 15mm - 20mm - 25mm and 50mm.

Clamp Pneumatic operated , 38mm wide with 4mm gap.

Electronic Output GraphMaster compatible RS232 serial data output with 9

pin, printer output and optional analog signal output

Electrical 120 V/60 Hz or 220V/50 Hz

Air connection 6mm OD plastic hose

Dimensions Length : 490 mm Width : 425 mm Height : 260 mm

Weight : ± 20 kg

Tests Performed

Score Bend

Score Perforation Break Force

Taber Stiffness

Bending Resistance

Spring Back.

Standards

ISO 2493

AS/NZ 1301-4535

BS 3748

DIN 53121

SCAN P29

TAPPI T556

Can be directly calibrated to traceable national standards


1. A bending resistance tester consisting of a clamp 38.0 ± 0.1 mm (1.5 in.) wide with

clamping surfaces mounted at 90 ± 1.0°. It can be pivoted about a vertical axis through

the front edge of the clamping nip, and turned at a constant speed of 5° ± 0.5° per second

through bending angles of 7.5 ± 0.1° or 15.0 ± 0.1°.

2. A knife mounted vertically at 90 ± 1.0° and attached to a transducer. The length of knife-

edge is 16 ± 2 mm (0.6 ± 0.08 in.) and the edge is centrally placed relative to the width

of the test piece. The distance from its edge to the pivot axis of the clamp is normally

adjusted to 50.0 ± 0.1 mm (2.0 in.) or 10.0 ± 0.1 mm (0.4 in.). The knife also mounted at

90 ± 0.1° in the direction perpendicular to the specimen.

3. The clamp must be at least 38 mm (1.5 in.) wide and at least 20 mm (0.8 in.) long with

two flat and parallel jaws clamping the test piece uniformly. Normally, a clamping

pressure of 200 ± 50 kPa (30 ± 7 psi) is suitable.

4. The force transducer shall have a range between 0-1000 mN (0-2.25 lbf), or an optional

0-10,000 mN range, with an accuracy of ±1.0% of the nominal range. The transducer

should have minimum sensitivity to lateral forces, and its movement in its response

direction should be less than 0.05 mm (0.002 in.) when covering the full range of

measurement.

5. An electronic holding circuit that can be checked accurately with dead weight loads and

which records the maximum force exerted on the knife-edge with an error over the entire

range of the measurement not exceeding 2% of the scale reading, but not greater than 1%

of the load range.

6. Simple cutter, to cut specimen, 38 mm ± 0.1 mm (1.5 in.) and 76 mm (3 in.) long.


1. When testing paperboard, set the knife-edge of the bending resistance tester 50.0 ± 0.1

mm (0.2 in.) from the pivot axis of the clamp. For paper, set the knife-edge 10.0 ±0.1

mm (0.4 in.).

2. Position the specimen in the clamp so that the longer side is horizontal and the clamped

end of the specimen fills the clamp. Make sure that the test piece is long enough to have

a free length beyond the clamp of 7±3mm.

3. Adjust the knife carefully until it just makes contact with the specimen along the vertical

line and so that the force indicator just reacts but registers no more than 1 Nm. Avoid

bending the specimen before the test begins.

4. Start pivoting the clamp, watch the instruments and note the maximum scale reading

when the clamp has turned through 15°, the full bending angle.

5. If the maximum force is obtained before the test piece has been pivoted through 15°, a

break is indicated.

6. Use clamping length and test angle determined in 7.1 and 7.5, and a test speed of 5±0,1°

per second.

7. Use each specimen only once. Test 10 specimens in the cross machine and 10 in the

machine direction. For each direction test 5 specimens toward the wire side and 5 toward

the felt side.

REFERENCE

TAPPI T403 Bursting strength of paper

TAPPI T414 Internal tearing resistance of paper (Elmendorf type-method)

TAPPI T459 Surface strength of paper (wax pick test)

TAPPI T460 Air resistance of paper (Gurley method)

TAPPI T479 Smoothness of paper (Bekk method)

TAPPI T494 Tensile properties of paper and paperboard (using constant rate of

elongation apparatus)

TAPPI T555 Roughness of paper and paperboard (Print-surf method)

TAPPI T556 Bending resistance of paper and paperboard by single-point bending

method

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