Scientiﬁc Soapmaking - Caveman Chemistrycavemanchemistry.com/BCCE2008b.pdf · Why Teach Soapmaking? Why Teach Soapmaking? • Thriving cottage industry • Soapmakers generally

Scientific Soapmaking

Kevin M. Dunn

Summer 2008

$Revision: 1.1 $

1

Acknowledgements

Copyright © 2008 Kevin M. Dunn

Acknowledgements

• Mike Lawson/Columbus Foods

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

• 100.00 g Delight (an oil blend)

• 28.80 g Lye (500 ppt NaOH)

Let’s Make Soap

Let’s Make Soap

• 100.00 g Delight (an oil blend)

• 28.80 g Lye (500 ppt NaOH)

• But how are we to weigh?

Weighing Synthetically

Weighing Synthetically

• Place cup of water on balance

• Press tare button

• Use pipet to transfer water to second cup

• What if we overshoot?

• What about the water in the pipet?

Let’s Make Soap

Let’s Make Soap

• 100.00 g Delight (already weighed)

• 28.80 g Lye (weigh synthetically into oil)

Let’s Make Soap

Let’s Make Soap

• 100.00 g Delight (already weighed)

• 28.80 g Lye (weigh synthetically into oil)

• Shake vigorously for 60 seconds

• Pour into styrofoam cup

• 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 KOH1 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

Tota

l A

lkali

(p

pt

NaO

H)

Alkali Ratio (ppt NaOH)

1 Day Old

0

2

4

6

140 144 148 152 156

Tota

l A

lkali

(p

pt

NaO

H)

Alkali Ratio (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 Std1.XX g Oil

)(4.ZZ g KOH1000 g Std

)=

(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 Std1.XX g Oil

)(4.ZZ g KOH1000 g Std

)=

(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

)= 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 Bottom

A Palm1000Lye286 111 54 1.8 4.9 0.3 0.9

B Palm1000Lye286Aq143 200 60 1.8 1.4 -1.7 -0.2

C Palm1000Lye286Aq286 273 74 0.5 0.3 -1.7 -0.1

0

100

200

300

0 30 60

pp

t

Days

Moisture

ABC

0

5

10

0 30 60

kg/s

cm

Days

Hardness

Coconut Oil

Coconut OilBatch Code Moisture/ppt Alkali/ppt NaOH



D Coconut1000Lye348 129 41 0.4 0.5 -0.6 -0.3

E Coconut1000Lye348Aq174 229 88 -0.1 -0.2 -1.7 -1.0

F Coconut1000Lye348Aq348 308 109 0.1 0.2 -1.8 -0.4

0

100

200

300

0 30 60

pp

t

Days

Moisture

DEF

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


1.7A Olive1000Lye264 104 36 0.3 0.2 -3.2 -0.4

3.5A Olive990Clove10Lye259 103 43 -0.4 -0.7 -0.7 -0.7

3.5B Olive990Clove10Lye259Aq130 187 61 -0.4 -0.4 -0.8 -0.7

3.5C Olive990Clove10Lye260Aq260 256 67 -0.7 6.2 -1.1 -0.2

0

100

200

300

0 30 60

pp

t

Days

Moisture

1.7A3.5A3.5B3.5C

0

5

10

0 30 60

kg/s

cm

Days

Hardness

Delight

Delight

• Delight = Olive390Palm280Coconut280Castor50

Delight

Delight

Batch Code Moisture/ppt Alkali/ppt NaOH



A Delight1000Lye288 112 48 -0.2 0.2 -1.0 -0.4

B Delight1000Lye288Aq144 201 89 -0.4 0.3 -3.1 -0.9

C Delight1000Lye288Aq288 274 104 -0.9 0.9 -3.7 -1.3

0

100

200

300

0 30 60

pp

t

Days

Moisture

ABC

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


Conclusions

Conclusions

• I encountered no problems with lye concentrations up to 50%.

Conclusions

Conclusions


• High-water Olive and Delight soaps separated.

Conclusions

Conclusions



• More water delays trace.

Conclusions

Conclusions




• Low-water soaps start out hard; medium- and high-water soapsmay or may not “catch up.”

Conclusions

Conclusions





• “Gel phase” was observed only for medium- and high-watersoaps. Since all soaps were fully saponified, gel phase is not es-sential. In fact, when separation occurred, it always happenedduring gel phase.

Conclusions

Conclusions





• “Gel phase” was observed only for medium- and high-watersoaps. Since all soaps were fully saponified, gel phase is not es-sential. In fact, when separation occurred, it always happenedduring gel phase.

• Saponification and curing are two separate processes.

Recommendations

Recommendations

• Decide on a standard lye concentration and always use thatwhen making soap.

Recommendations

Recommendations


• You can always add extra (water, milk, etc.) to delay trace ordecrease initial hardness.

Recommendations

Recommendations



• If oil separates from the soap, try decreasing the amount of (wa-ter, milk, etc.).

Recommendations

Recommendations




• Be aware that soaps may continue to lose moisture, even after60 days.

Recommendations

Recommendations




• Be aware that soaps may continue to lose moisture, even after60 days.

• Make lye only from NaOH and water.

Checking In

Checking InWhat are the temperature and consistency of your soap?

Summary

Why Am I Teaching You to TeachSoapmaking?

• There is a market for soapmaking instruction

Summary



• Soapmaking can motivate gen-ed students

Summary




• Online soapmaking communities are fraught with MSU

Summary




• Online soapmaking communities are fraught with MSU

• I’m lonely

Summary

Organizations

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

• The Saponifier (www.Saponifier.com)

• Scientific Soapmaking (www.ScientificSoapmaking.com)

www.SoapGuiild.org

www.Saponifier.com

www.ScientificSoapmaking.com

Documents

Scientiﬁc Soapmaking - Caveman Chemistrycavemanchemistry.com/BCCE2008b.pdf · Why Teach Soapmaking? Why Teach Soapmaking? • Thriving cottage industry • Soapmakers generally