Original thread where I got this idea: http://www.soapmakingforum.com/showthread.php?p=603611#post603611
Not sure if this belongs in its own thread, in this section, or in the other thread. I hope it's ok to post this here. If not, I'm happy to delete this and post it elsewhere.
I spent about 20 minutes doing math before I started making the soap. This is math heavy but I bold the parts that are important. Feel free to only read the parts in bold.
I went ahead and did my own FFA pH reduction experiment to see if I could lower the pH of a soap with FFA or if it was the same as SFing with straight oil (triglycerides).
In order to get free fatty acids in a soap, I needed to add an acid after cooking the soap via HP. This is because the soap will already have reacted with the lye to give FFA salts and glycerin. When I add an acid, it will give back the FFAs themselves, increasing the SF of the soap.
I didn't realize the original post was in the liquid soap forum so I made this as a bar soap. I used a 100% coconut oil recipe with a 20% SF.
According to soapee, 20% SF.
200 g coconut oil
29.3 g Sodium Hydroxide
Some amount of water
I knew that I would need to add acid into the soap with FFAs so I needed to do the same with the triglyceride soap in a way that won't generate FFAs.
I wanted to add the equivalent NaOH to give 20% left over FFAs. That meant I needed to add 20%/100% * 29.3g NaOH = 5.9 g more NaOH to the batch and 5.9/.64 (grams of lye per 1 gram of citric acid neutralized) = 9.2 g Citric acid to neutralize that extra lye. That gives me a net change of zero SF for the soap. Meaning it stays at 20%.
I decided to use a 2:1 Water: NaOH/CA ratio
That meant for both batches I needed to use:
200 g coconut oil
35.2 g NaOH
9.2 g CA
89 g water
The difference in the two batches would be the ingredient order.
Triglyceride (Oil) soap
1. 160 g of coconut oil melted in slow cooker
2. Made my lye solution by adding 9.2 g CA to 89 g water. Then I added the 35.2 g NaOH very slowly to clarity.
I mixed the lye and oil together to trace and cooked it. After it reached the paste stage (finished cooking) I added 40 g coconut oil. It was very brittle so I added 10 more g of water. Important part: Left with 20% unreacted oil
FFA Soap
1. 200 g coconut oil melted in slow cooker
2. Made lye solution by adding 35.2 g NaOH to 70.6 g water
I mixed the lye and oil together to trace and cooked it. After it reached the paste stage, I added 9.2 g CA dissolved in 18.4 g water. After mixing, I added another 10 g water to match the triglyceride batch. Important part: Left with 20% FFA
Observations
Triglyceride Soap
- Difficult to trace (could be due to high salt content)
- Separated in the pot after ~20 minutes (also could be high salt content)
-Took a while to come together
-When it did, it solidified almost instantly
-Didnt change much when I added 40 g of coconut oil
-Finally loosened some with additional 10 g water
- Difficult to get into the mold
-Very crumbly and hardened super fast.
-Very opaque soap
pH in 1% solution of distilled water by test strips: 9-10; ~9.5
FFA Soap
-Came to trace in expected time frame
-Did not separate
- More fluid at paste stage
-Smelled funky when I added the CA solution
- Became VERY fluid!!
- Easy to pour and did not solidify quickly
- Took longer to solidify
- More transluscent soap
- Had more bubbles and held bubbles for longer than the triglyceride soap
pH in 1% solution with distilled water by test strips: 9-10; ~9.5
Thoughts on what this all means:
1. So, it didn't seem to effect pH. However, it did make other, important differences. I also don't have proper pH testing materials. I wonder what a pH meter would read. Please note during the time I was writig this TOMH posted that the referenced experiments were done at 40% SF. I will be re-doing this experiment at this level to see whether pH is affected. I do not have HCl to try with. I will stick to citric acid. There may be some equilibrium issues with this.
2. Maybe adding yogurt or other acidic foods after cooking in HP works so well because it creates FFAs and that's what actually makes the soap more fluid! This is definitely something to look into! It could also be why fluid HP seems so variable. I wonder if some FFAs contribute to fluidity more than others.
3. Why does the FFA soap give off substantially more bubbles that also last longer? Most likely glycerin! The FFA soap has a higher glycerin amount because the glycerin has been formed from saponifiying all of the oil. The soap that has the oil added at the end has all glycerin bound up within the triglycerides. After adding the acid to the FFA soap, the glycerin is still free and present.
4. Why the smell in the FFA soap? Some FFAs have a scent whereas most triglycerides do not. The scent is not particularly pleasant but its not terrible either. It could probably be covered up by a fragrance.
5. Things I will be looking for in the coming weeks:
I will be using the soaps at 1 week, 4 weeks and 8 weeks to determine differences.
Let me know if you find any mistakes or have other questions to add.
Edited to add pictures
Not sure if this belongs in its own thread, in this section, or in the other thread. I hope it's ok to post this here. If not, I'm happy to delete this and post it elsewhere.
I spent about 20 minutes doing math before I started making the soap. This is math heavy but I bold the parts that are important. Feel free to only read the parts in bold.
I went ahead and did my own FFA pH reduction experiment to see if I could lower the pH of a soap with FFA or if it was the same as SFing with straight oil (triglycerides).
In order to get free fatty acids in a soap, I needed to add an acid after cooking the soap via HP. This is because the soap will already have reacted with the lye to give FFA salts and glycerin. When I add an acid, it will give back the FFAs themselves, increasing the SF of the soap.
I didn't realize the original post was in the liquid soap forum so I made this as a bar soap. I used a 100% coconut oil recipe with a 20% SF.
According to soapee, 20% SF.
200 g coconut oil
29.3 g Sodium Hydroxide
Some amount of water
I knew that I would need to add acid into the soap with FFAs so I needed to do the same with the triglyceride soap in a way that won't generate FFAs.
I wanted to add the equivalent NaOH to give 20% left over FFAs. That meant I needed to add 20%/100% * 29.3g NaOH = 5.9 g more NaOH to the batch and 5.9/.64 (grams of lye per 1 gram of citric acid neutralized) = 9.2 g Citric acid to neutralize that extra lye. That gives me a net change of zero SF for the soap. Meaning it stays at 20%.
I decided to use a 2:1 Water: NaOH/CA ratio
That meant for both batches I needed to use:
200 g coconut oil
35.2 g NaOH
9.2 g CA
89 g water
The difference in the two batches would be the ingredient order.
Triglyceride (Oil) soap
1. 160 g of coconut oil melted in slow cooker
2. Made my lye solution by adding 9.2 g CA to 89 g water. Then I added the 35.2 g NaOH very slowly to clarity.
I mixed the lye and oil together to trace and cooked it. After it reached the paste stage (finished cooking) I added 40 g coconut oil. It was very brittle so I added 10 more g of water. Important part: Left with 20% unreacted oil
FFA Soap
1. 200 g coconut oil melted in slow cooker
2. Made lye solution by adding 35.2 g NaOH to 70.6 g water
I mixed the lye and oil together to trace and cooked it. After it reached the paste stage, I added 9.2 g CA dissolved in 18.4 g water. After mixing, I added another 10 g water to match the triglyceride batch. Important part: Left with 20% FFA
Observations
Triglyceride Soap
- Difficult to trace (could be due to high salt content)
- Separated in the pot after ~20 minutes (also could be high salt content)
-Took a while to come together
-When it did, it solidified almost instantly
-Didnt change much when I added 40 g of coconut oil
-Finally loosened some with additional 10 g water
- Difficult to get into the mold
-Very crumbly and hardened super fast.
-Very opaque soap
pH in 1% solution of distilled water by test strips: 9-10; ~9.5
FFA Soap
-Came to trace in expected time frame
-Did not separate
- More fluid at paste stage
-Smelled funky when I added the CA solution
- Became VERY fluid!!
- Easy to pour and did not solidify quickly
- Took longer to solidify
- More transluscent soap
- Had more bubbles and held bubbles for longer than the triglyceride soap
pH in 1% solution with distilled water by test strips: 9-10; ~9.5
Thoughts on what this all means:
1. So, it didn't seem to effect pH. However, it did make other, important differences. I also don't have proper pH testing materials. I wonder what a pH meter would read. Please note during the time I was writig this TOMH posted that the referenced experiments were done at 40% SF. I will be re-doing this experiment at this level to see whether pH is affected. I do not have HCl to try with. I will stick to citric acid. There may be some equilibrium issues with this.
2. Maybe adding yogurt or other acidic foods after cooking in HP works so well because it creates FFAs and that's what actually makes the soap more fluid! This is definitely something to look into! It could also be why fluid HP seems so variable. I wonder if some FFAs contribute to fluidity more than others.
3. Why does the FFA soap give off substantially more bubbles that also last longer? Most likely glycerin! The FFA soap has a higher glycerin amount because the glycerin has been formed from saponifiying all of the oil. The soap that has the oil added at the end has all glycerin bound up within the triglycerides. After adding the acid to the FFA soap, the glycerin is still free and present.
4. Why the smell in the FFA soap? Some FFAs have a scent whereas most triglycerides do not. The scent is not particularly pleasant but its not terrible either. It could probably be covered up by a fragrance.
5. Things I will be looking for in the coming weeks:
I will be using the soaps at 1 week, 4 weeks and 8 weeks to determine differences.
Let me know if you find any mistakes or have other questions to add.
Edited to add pictures
Last edited:
