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Timber Floors….

Will future coatings address current colour

problems? DavidHayward-ATFA

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Coatings and stains – a wide range

Some coating systems are more hard wearing but not as easy to repair.

Some are better for certain installation environments. Some are better with some timbers than others.

The coated appearance differs between types, within types and differs over time.

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Qld Spotted Gum flooring with an oil based finish.

Our members provide floors for family homes

Brush Box rhomboid parquetry ‘direct stick’ to concrete. Water based finish..

American White Oak, plank on ply. Custom stain and oil based finish.

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Spotted Gum flooring, installed on battens for a busy restaurant. Hard wax oil finish.

Our members provide commercial floors

Ironbark with Blackbutt dots, Treasury casino Brisbane. Water based finish.

Limed Tasmanian Oak with a homogeneous velvet white oil.

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Appearance is important …. This is why

“Given that manufactured products are meant to fulfill an intended purpose, their appearance is one of their most important commercial attributes.

Appearance often determines the acceptability of a product to its seller, and ultimately to the consumer or end-user.

The quality of a product’s appearance is psychologically related to its expected performance and useful life. It therefore determines its reception (or rejection) by potential purchasers.

All other things being equal, when consumers have a choice, they buy what looks best. Appearance is the foremost and most impressive product message.”

Graphic Arts Technical Foundation, 2001Richard W. Harold

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Firstly we will consider colour

The human visual system has three colour sensors which can be approximated by measuring the red green and blue components of light at a location.

Red plus green is perceived as yellow Red plus blue magenta Green plus blue cyan

All three in the right proportions white

What we see is the mix of wavelengths not absorbed by the wood.

Note to the left, ultraviolet light, is known to affect timber colour over time, but visible light also affects timber colour with time.

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Our perception of colour

Humans are good at •  Recognising characteristics

such as knots. •  Recognising unexpected

changes such stain discolouration.

Humans are poor at •  Estimating colour •  Maintaining long-term

consistency in what a colour looks like

The colour we perceive depends on the background colours.

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Wood changes colour with light

Timber, like many natural materials (such as your skin), will change colour on exposure to the ultraviolet (UV) radiation in sunlight.

Just as different people respond to exposure to sunlight in different ways, the responses of different timber species to sunlight are quite variable.

Colour changes are due mainly to differences in chemical composition of wood from different species (or even in the same timber species with different ages or growth rates).

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Colour changes in wood

* 650 hours of sunlight exposure will be equivalent to at least two years service for an area of floor which may be exposed to two hours of direct sunlight per day, behind untinted windows.

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What is the concern if colour change is natural?

It is the colour changes that become so intense and which can occur over a relatively short period of time.

It is the colour changes that can occur for reasons that we don’t understand particularly in some engineered flooring.

It is colour variation as part of the manufacturing process which then can become more accentuated due to the coating type.

It is the change in colour of some coating and sealer combinations that occur over time.

It is the colour change that occurs with spills on the floor or from pet accidents or household products.

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Simulated 2 year colour change with PU coating

If this was the case we would not be talking about this today!

This

to this I bought this I got this ?

Sun exposedHad been covered

What is the concern if colour change is natural?

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Some timber species change a lot in colour

The owner purchased this …… And got this after a short period of time

Is this enough when the colour change is going to be rapid and intense in this species?

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Colour change in Jarrah with sun exposure

In this house why did the Jarrah bleach so much?

Another house with Jarrah – not sun exposed above and sun exposed below.

So why did one dark heartwood board stay dark

when sun exposed and

the other didn’t.

You would think this has to be more than wood and light.

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The effects associated with rugs

Solid prefinished Merbau

Original flooring 5 years old still in the dwelling

Is this acceptable?

Replaced section of floor with the floor

rug removed

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More on rugs

Factory oiled coating An applied water based PU

But we also see houses where there is little to no colour change under rugs even though the rugs have been there from day one…. why?

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I bought this

6 months later I got this

What is the concern if colour change is natural?

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Floor colour and lighting systems

Ultimately, color deterioration in hardwood floors is the result of overexposure from 3 things: ultraviolet (UV) light, visible light and the infrared (IR) light which causes solar heat.

Lighting source

Colour impact UV bleaching effect

Incandescent Warm yellow amber like. Makes reds, oranges and yellows more vivid.

No

Fluorescent Flat cool light tones down reds, oranges and yellows

Yes

Halogens Resemble natural light and make shift from daylight to artificial light less jarring

No

Compact Fluorescent

Can produce various colour impact depending on type.

Possible

Light – emitting Diodes (LED’s)

Most lack in the red end of the spectrum that tones down red and brown hues

No

Have we also considered that different lighting sources may affect ongoing floor colour differently?

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Jarrah floor colour affected by LED lighting

Jarrah floor LED down lights turned off LED down lights turned on So this is an instantaneous effect of many LED lights not having enough reds in them. Light type affects colour.

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Generally a sealer coat and two top coats of water based polyurethane is used.

Colour change when water based ‘poly’ is used

Sealer coats used include:- •  Water based sealers – provides a compatible all water based

system but care is needed with grain raise. Poor colour development in darker timbers. Care to avoid lap marks.

•  Alcohol based sealers – Better colour development and reduced grain raise. Provides a compatible system. Can get lap marks.

•  Oil based sealers – Trowelled on and buffed in. Good colour development, no grain raise or lap marks but needs to be overnight before overcoating.

•  Polyurethane sealers – Recently introduced, very good colour development, needs to be left overnight and cut back. They are compatible with water based coatings.

•  Solvent based fast dry sealers – reduces effect of extractables from timber (e.g. oils and tannins) and enhances colour development. But often a mixed system with water based coatings and affecting warranties.

So why do so many contractors use solvent sealers that void warranties

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Colour change where water based is used

Solvent sealer and 2 coats of WB polyurethane

Water based sealer and 2 coats of WB polyurethane

Test panel with two months sun exposure

A more even tone retaining more reds

This board is lighter toned

Darker tannins have emerged in this board.

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Is this the contractors fault? I just use water to clean my floors!

Are pet stains all the owners fault? It didn’t happen in my previous floor!

Some other aspects

Are household sprays the owners fault? It didn’t happen with solvent based ‘poly’!

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Water based polyurethane over fast dry sealer

Where sun exposed the cork and timber have a bleached appearance.

Where not sun exposed but with internal lighting the floor and cork have deepened in colour tone.

We will now consider the differences in appearance throughout a single dwelling.

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Where the cupboard is mainly closed it is not exposed to internal lighting and maintains the initial colour after coating. This is similar under the entrance door floor mat although other colour variations are present.

Water based polyurethane over fast dry sealer

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Water based polyurethane over fast dry sealer

The same photo on the left with the entrance mat removed. But to the right a floor rug, reported to have been there from day one and no colour change beneath it.

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Water based polyurethane over fast dry sealer

Sealer + WB coating + sunlight = bleached appearance

Sealer + WB coating + internal lighting = deeper brown red tones

Sealer + WB coating + little internal lighting = lighter brown tones

Does timber colour change account for this bleached appearance ?

Why are we getting coating marks appearing in the floor? Is it the sealer or the coating?

Why did the mat at the front door have a different effect to the floor rug in the lounge?

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Ghosting is another colour change mystery to us

Traditional ghosting relates to boot, shoe or foot marks that appear as an opaque outline of the shoe sole or foot that usually becomes apparent some 3 to 24 months after the floor is sanded and coated.

It is important to realise that this has been seen in many timbers and most coatings, although it is more visible in darker timbers.

So who is wearing these when they are coating floors?

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A case study on a ghosted floor

Toowoomba about 1 ½ hours drive west of Brisbane and is on an escarpment. This floor had some pronounced and well developed ghosting.

•  AGE - In this 4 ½ year old house, ghosting started appearing from a few months and continued to develop.

•  COATING SYSTEM - Solvent based fast dry sealer then single pack moisture cured polyurethane top coats.

•  WEATHER - Wet at the time of coating.

•  EXPERIENCE - The flooring contractor had 15 years sanding and coating experience and mainly uses this coating system.

•  OCCURENCES - During this 15 years he has had three ghosting problems in Toowoomba and none in Warwick where he also does a lot of work.

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Ghosting in this Toowoomba floor

None under the rug, there from day one

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What we should consider

Some observations: •  Prints crossed board boundaries so has

happened after sanding. •  The work boot was not the footwear used by the

floor coating contractor. •  Under the rug there were no prints, so after

occupancy nobody regularly walks on this area and it is protected from UV light.

•  Generally at doorways and where more light exposed, there was more ghosting.

•  Both prints and smudges were present. •  A fast dry sealer was used. •  Conditions at the time of coating were wet.

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Some questions?

•  Dark boards are often higher density boards and without more permeable sapwood.

•  But in these photos one dark board is more affected while in the other photo less affected.

Why are some boards more affected than others?

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Some other images of ghosting in other floors

The soles of some boots are more prone

It is not only footwear but can be bare feet

Solvent based sealer and water based PU top coats

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Ghosting in a water affected floor

In the water affected floor

Boards some months later

•  The owner commented that the ghosting appeared worse after the floor was flooded…(oh, yeah…)

•  When I got the boards a few months later I noticed a lessening in the intensity present in some boards compared to others.

•  Some in NZ consider moisture contamination is a cause.

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Ghosting – a theory

They liken it to the effect of tape on timber. When firmly pressed it becomes transparent but where not firmly pressed or there are bubbles (‘delamination’) its opaque.

Some consider it a coating delamination issue: •  Oils on feet of footwear perhaps one fundamental cause and

could wet feet or footwear.

•  Where the oils or moisture is, there is in time delamination of the coating and light reflection that provides the opaque appearance.

•  Also, photo-degradation is not necessary for a delamination mechanism but it could contribute e.g. increase the rate of delamination.

•  As the delamination spreads with time so does the ghost print develop with time.

•  A contractor in Australia has also indicated that where he has had ghosting in a floor there was delamination through the opaque area of coating.

So why can we see it on stair risers?

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Colour changes in timber floors

We can accept gradual colour changes that appear natural, either as part of a wood characteristic or a gradual aging process.

However, it is the dramatic and vivid differences that can occur over relatively short to moderate time periods that become unacceptable and includes aspects relating to the robustness of the coating.

We want differences in appearance from different coatings, but also wanting the coating system to provide a positive appearance change with time.

Will coatings of the future address the colour problems of today?

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Thankyou