Scientific Soap Making

Scientific Soapmaking

Kevin M. Dunn

Summer 2010

$Revision: 1.1 $

1

Acknowledgements

Copyright © 2010 Kevin M. Dunn

Acknowledgements

• Mike Lawson/Columbus Foods

• Scientific Soapmakers

2

Why Teach Soapmaking?


• Thriving cottage industry




• Soapmakers generally come from a cooking/craft background





• Soapmakers are interested in the chemistry of their craft






• If gen-ed students can imagine themselves as soapmakers, theywill become interested in the chemistry






• If gen-ed students can imagine themselves as soapmakers, theywill become interested in the chemistry

• Experiments are designed to solve real-world problems

Let’s Make Soap

Let’s Make Soap

• 1000 g Delight (an oil blend)

• 288 g Lye (500 ppt NaOH)

Let’s Make Soap

Let’s Make Soap

• 1000 g Delight (an oil blend)

• 288 g Lye (500 ppt NaOH)

• But how are we to weigh?

Weighing Synthetically

Weighing Synthetically

• Place bottle of lye on balance

• Press tare button

• Use cup to transfer lye to jug of oil

• What if we overshoot?

• What about the lye in the cup?

Let’s Make Soap

Let’s Make Soap

• 1000 g Delight (already weighed)

• 288 g Lye (weigh synthetically into oil)

Let’s Make Soap

Let’s Make Soap

• 1000 g Delight (already weighed)

• 288 g Lye (weigh synthetically into oil)

• Shake vigorously for 60 seconds

• Pour into styrofoam cups

• Measure temperature

Oil and Water

Oil and Water

Glyceryl Trilaurate

Glyceryl Trilaurate

O

O

O

O

O

O

Saponification

Saponification

Saponification

SaponificationNaOH

O

O

O

O

O

O

NaOH NaOH

↓

ONa

O

OH

OH

OH

ONa

O

ONa

O

Saponification

Saponification

• Oil + 3 NaOH = Glycerol + 3 Soap

• Each molecule of oil requires 3 molecules of NaOH

Saponification

Saponification



• What happens if you provide only 2 molecules of NaOH?

Saponification

Saponification




• What happens if you provide 4 molecules of NaOH?

Saponification

Saponification





• We measure oil and NaOH by weight, not by molecules

Saponification

Saponification





• We measure oil and NaOH by weight, not by molecules

• Each gram of oil should require a specific weight of NaOH forcomplete saponification

Saponification Value

Saponification ValueTheoretical saponification value of glyceryl tristearate:

? g KOH = 1000 g oil(1 mol oil890 g oil

)(3 mol KOH

1 mol oil

)(56 g KOH

1 mol KOH

)= 189 ppt KOH

Experimental saponification value of tallow: 190-200 ppt


Saponification ValueTheoretical sodium saponification value of glyceryl tristearate:

? g NaOH = 1000 g oil(1 mol oil890 g oil

)(3 mol NaOH

1 mol oil

)(40 g NaOH

1 mol NaOH

)= 135 ppt NaOH

Experimental sodium saponification value of tallow: 135-143 ppt



• SV = weight (mg) of KOH needed to saponify 1 g of oil

• SSV = weight (mg) of NaOH needed to saponify 1 g of oil

• AR = weight (mg) of alkali actually used to saponify 1 g of oil






• SV of Delight is 211.5 ppt KOH

• SSV of Delight is 150.8 ppt NaOH






• SV of Delight is 211.5 ppt KOH

• SSV of Delight is 150.8 ppt NaOH

• Since Lye is 500 ppt NaOH, we have used an AR of 144 pptNaOH

• Why?

Lye Discounting

Lye Discounting

0 2 4 6

140 144 148 152 156

TA /

ppt N

aOH

AR / ppt NaOH

1 Day Old

0 2 4 6

140 144 148 152 156

TA /

ppt N

aOH

AR / ppt NaOH

11 Weeks Old

Checking In

Checking InWhat are the temperature and consistency of your soap?

Measurable quantities

Measurable Quantities

• Finished soap• Total alkali• Moisture content• Hardness

Measurable quantities

Measurable Quantities

• Finished soap• Total alkali• Moisture content• Hardness

• Raw materials• Saponification value• Lye concentration• Free fatty acid

Free Fatty Acid

Free Fatty Acid

• Real-world oils may contain “free” fatty acid

• How can we measure it?

Titration

Titration

Titration

Titration

• Add 50 mL ethanol to Erlenmeyer flask

• Add 4-5 drops 1% phenolphthalein

• Add 4.18 ppt KOH until solution is faintly pink

• Solution is now “neutral”

Weighing Analytically

Weighing Analytically

• Place coconut oil bottle on balance


• Transfer 30-40 drops of oil to Erlenmeyer flask

• Replace oil bottle on balance and read weight

Gravimetric Titration

Gravimetric Titration

• Place 4.18 ppt KOH bottle on balance


• Add KOH to Erlenmeyer flask until faintly pink

• Replace KOH bottle on balance and read weight

Acid Value

Acid Value

? g KOH = 1000 g oil(YY.YY g standard

1.XX g oil

)(4.ZZ g KOH

1000 g standard

)AV =

(YY.YY1.XX

)4.ZZ ppt KOH

• What is the Acid Value of your oil?

Acid Value

Acid Value

? g KOH = 1000 g oil(YY.YY g standard

1.XX g oil

)(4.ZZ g KOH

1000 g standard

)AV =

(YY.YY1.XX

)4.ZZ ppt KOH

• What is the Acid Value of your oil?

• Why did we get different values?

Free Fatty Acid

Free Fatty Acid

• Free Lauric Acid = 3.570 AV

• What is the Free Lauric Acid content of your oil?

Free Fatty Acid

Free Fatty Acid

• Free Lauric Acid = 3.570 AV

• What is the Free Lauric Acid content of your oil?

• Which oil would saponify quicker?

Extended Investigations


• Dreaded Orange Spots




• Seizing




• Seizing

• Superfatting vs Discounting




• Seizing

• Superfatting vs Discounting

• The Water “Discount”

Lye Concentration

Lye Concentration

• What is the normal, correct, or standard lye concentration?

Lye Concentration

Lye Concentration


• Ann Bramson, Soap: Making it, Enjoying it (1972)

25-27%, 26% average

Lye Concentration

Lye Concentration



25-27%, 26% average

• Susan Cavitch, The Soapmaker’s Companion (1997)

26-29%, 27% average

Lye Concentration

Lye Concentration



25-27%, 26% average


26-29%, 27% average

• Robert McDaniel, Essentially Soap (2000)

33-38%, 34% average

Lye Concentration

Lye Concentration



25-27%, 26% average


26-29%, 27% average

• Robert McDaniel, Essentially Soap (2000)

33-38%, 34% average

• Anne Watson, Smart Soapmaking (2007)

30-37%, 33% average

The Soap Formula

The Soap Formula

• Lye = 50.00% NaOH, 50.00% distilled water

• Coconut1000Lye348

Coconut1000Lye348Aq174

Coconut1000Lye348Aq348

The Soap Formula

The Soap Formula

• Lye = 50.00% NaOH, 50.00% distilled water

• Coconut1000Lye348 (50.00% NaOH “Low-Water”)

Coconut1000Lye348Aq174 (33.33% NaOH “Medium-Water”)

Coconut1000Lye348Aq348 (25.00% NaOH “High-Water”)

Processing Soap

Processing Soap

• 100 g oil + water + lye into 500 mL plastic bottle

• Shaken 15 sec on a paint shaker

• Gently swirled until trace

• Poured into an Upland experimental mold

• Incubated at 140◦F for 4 hours

Questions

Questions

• What do we want to know?

Questions

Questions

• What do we want to know?

• Does the initial water portion affect the final moisture content?

• Does it affect the curing time?

• Does it effect the hardness of the soap?

• Is there a danger of separation?

What Can We Measure?


• Moisture content of soap over time

• Hardness of soap over time

• Alkalinity of soap over time

• Separation of soap




Initially from formula, follow weight loss over time









Soil penetrometer








Soil penetrometer


Titration with 5 ppt citric acid







Soil penetrometer


Titration with 5 ppt citric acid


Hardness of top and bottom of bar

Alkalinity of top and bottom of bar

Moisture

Moisture

• Coconut1000Lye348Aq348

• Total weight 1696 g

• Water weight (174 + 348) = 522 g

• Initial moisture = (522/1696) = 0.308 = 30.8% = 308 ppt

Moisture

Moisture

• Coconut1000Lye348Aq348

• Total weight 1696 g

• Water weight (174 + 348) = 522 g

• Initial moisture = (522/1696) = 0.308 = 30.8% = 308 ppt

• Initial bar weight 141.32 g; Final weight 113.17 g

• Weight loss (28.15/141.32) = 0.199 = 19.9% = 199 ppt

• Final moisture = 308 - 199 = 109 ppt

Penetrometer

Penetrometer

Smaller foot used for hard soaps.

Titration

Titration

How many grams of acid required to titrate a given weight ofsoap?

Total Alkali

Total Alkali

? g NaOH = 1000 g soap(Y.YY g acid1.XX g soap

)(5 g H3Cit

1000 g acid

)(

1 mol H3Cit192.12 g H3Cit

)(3 mol NaOH1 mol H3Cit

)(40.00 g NaOH1 mol NaOH

)TA = 3.123

(Y.YY1.XX

)ppt NaOH

Palm Oil

Palm Oil

• Low, Medium, and High Water soaps

• Identical in other respects

• Moisture and hardness measured weekly for 60 days

• Alkalinity measured at beginning and end

Palm Oil

Palm OilBatch Code Moisture (ppt) Alkali (ppt NaOH)KMD2007.12.27 Initial Final Initial Final

Top Bottom Top BottomA Palm1000Lye286 111 54 1.8 4.9 0.3 0.9B Palm1000Lye286Aq143 200 60 1.8 1.4 -1.7 -0.2C Palm1000Lye286Aq286 273 74 0.5 0.3 -1.7 -0.1

0

100

200

300

0 30 60

ppt

Days

MoistureABC

0

5

10

0 30 60

kg/s

cm

Days

Hardness

Coconut Oil

Coconut OilBatch Code Moisture (ppt) Alkali (ppt NaOH)KMD2008.1.8 Initial Final Initial Final

Top Bottom Top BottomD Coconut1000Lye348 129 41 0.4 0.5 -0.6 -0.3E Coconut1000Lye348Aq174 229 88 -0.1 -0.2 -1.7 -1.0F Coconut1000Lye348Aq348 308 109 0.1 0.2 -1.8 -0.4

0

100

200

300

0 30 60

ppt

Days

MoistureDEF

0

5

10

0 30 60

kg/s

cm

Days

Hardness

Olive Oil

Olive Oil

• Medium and high water soaps separated

• What can I do to accelerate trace?

Olive Oil

Olive Oil

• Medium and high water soaps separated.

• What can I do to accelerate trace? Add clove oil.

Olive Oil

Olive OilBatch Code Moisture (ppt) Alkali (ppt NaOH)KMD2008 Initial Final Initial Final

Top Bottom Top Bottom1.7A Olive1000Lye264 104 36 0.3 0.2 -3.2 -0.43.5A Olive990Clove10Lye259 103 43 -0.4 -0.7 -0.7 -0.73.5B Olive990Clove10Lye259Aq130 187 61 -0.4 -0.4 -0.8 -0.73.5C Olive990Clove10Lye260Aq260 256 67 -0.7 6.2 -1.1 -0.2

0

100

200

300

0 30 60

ppt

Days

Moisture1.7A3.5A3.5B3.5C

0

5

10

0 30 60

kg/s

cm

Days

Hardness

Delight

Delight

• Delight = Olive390Palm280Coconut280Castor50

Delight

Delight

Batch Code Moisture (ppt) Alkali (ppt NaOH)KMD2008.2.17 Initial Final Initial Final

Top Bottom Top BottomA Delight1000Lye288 112 48 -0.2 0.2 -1.0 -0.4B Delight1000Lye288Aq144 201 89 -0.4 0.3 -3.1 -0.9C Delight1000Lye288Aq288 274 104 -0.9 0.9 -3.7 -1.3

0

100

200

300

0 30 60

ppt

Days

MoistureABC

0

5

10

0 30 60

kg/s

cm

Days

Hardness

Delight

Gel Phase

• Delight1000Lye288Aq50

Tmax 151◦F after 180 minutes

Never reached gel phase

Total alkali: 1.3 ppt (top), -0.2 ppt (bottom)

Delight

Gel Phase



Never reached gel phase

Total alkali: 1.3 ppt (top), -0.2 ppt (bottom)



“Very dry vaseline” at 145◦F after 210 minutes

Total alkali: 0.5 ppt (top), 0.1 ppt (bottom)

Delight

Gel Phase


“Vaseline” with beads of oil at 151◦F after 195 minutes


Total alkali: -0.2 ppt (top), 4.0 ppt (bottom)

Delight

Gel Phase


“Vaseline” with beads of oil at 151◦F after 195 minutes





“Jello” with layer of oil at 156◦F after 180 minutes


Delight

Gel Phase

0

20

40

60

80

100

Aq288Aq144Aq0

40

80

120

160

200

100 200 300Te

mpe

ratu

re (o C)

Tem

pera

ture

(o F)

Moisture Content (ppt)

curd (solid)

curd + neat

neat (gel)

Soap phases determined by Differential Scanning Calorimetry

Conclusions

Conclusions

• Does the initial water portion affect the final moisture content?

Conclusions

Conclusions

• Does the initial water portion affect the final moisture content?Probably not, though moisture may take more than 60 days toequilibrate.

Conclusions

Conclusions


• Does it affect the curing time?

Conclusions

Conclusions


• Does it affect the curing time? Yes, more water initially length-ens the curing time.

Conclusions

Conclusions



• Does it effect the hardness of the soap?

Conclusions

Conclusions



• Does it effect the hardness of the soap? Yes, high-water soapsare softer initially, but may equilibrate to the same final hard-ness as low-water soaps.

Conclusions

Conclusions




• Is there a danger of separation?

Conclusions

Conclusions




• Is there a danger of separation? Yes, high-water soaps are moreprone to separation than low-water soaps.

Checking In

Checking InWhat are the temperature and consistency of your soap?

Scientific Soapmaking Class

Teaching Scientific SoapmakingEconomically

• Spring 2010, 26 students




• Each student paid $50 fee.




• Each student paid $50 fee

• Students self-organized into four “firms”






• Firms “bought” all equipment and supplies at list price







• Students kept 90% of the soap produced







• Each student kept more than $50 worth of soap

• Department kept all equipment and leftover supplies—no netcost to the Department


Teaching Economic Soapmaking

• 90 min lecture, 90 min lab each week




• 4 weeks startup, 5 weeks production, 4 weeks R&D





• Production period approximately one 8-hr day






• Juried soap sale used to “sell” production soap







• Each firm used GnuCash to track income and expenses








• 495 bars produced, 382 bars “sold” for $1746








• 495 bars produced, 382 bars “sold” for $1746

• Return on Equity: 47%, 88%, 102%, 118%


Juried Soap Sale

Rack used for curing, then displaying production soap


Juried Soap Sale

• Each firm set up a display of products with prices


Juried Soap Sale


• Each juror had $30 to “spend”


Juried Soap Sale



• Jurors kept the soaps they selected


Juried Soap Sale




• For each soap selected, 9 more “sold” at the same price


Juried Soap Sale





• Firms were allowed to change prices daily


Juried Soap Sale






• No real money changed hands, 90% of soap returned


Juried Soap Sale






• No real money changed hands, 90% of soap returned

• Average value of returned soap: $60/student


Grading Scientific Soapmaking

• 11% Homework

• 11% HSMG CP/HP Level I Exam

• 11% HSMG CP/HP Level II Exam

• 22% Cumulative Exam

• 11% Return on Equity

• 11% Analytical Project Report

• 22% Quarterly Report for Firm


Organizations

• The Handcrafted Soap Makers Guild (www.SoapGuild.org)

• The Saponifier (www.Saponifier.com)

• Scientific Soapmaking (www.ScientificSoapmaking.com)

www.SoapGuild.org

www.Saponifier.com

www.ScientificSoapmaking.com

Documents

Scientific Soap Making