Guidance sought for using stearic acid in cold process soap

[akseattle]

Okay, I'm looking to this forum for some more guidance. This time for stearic acid.

I would like to incorporate stearic acid into a recipe. This will be my first time using it.

The recipe I’ve run through SoapCalc is a deviation from my basic recipe- same oils, different percentages. My goal is to get a reasonably hard, creamy, soothing bar with reasonable lather for dry skin. For a 450 gram batch of oil the recipe is:

Lard: 25%, Beef Tallow 14%, Coconut Oil 22%, Olive Oil 20%, Castor Oil 12%, Shea Butter 6%, Stearic Acid 1%, 5% Superfat and 38% lye concentration, 2 tsp sugar, 1 tsp salt, 1 TBsp colloidal oats

I will avoid floral FO’s to not contribute to acceleration- at least until I have a better sense for using stearic acid and colloidal oats (just used colloidal oats for the first time last week.) Also, last week was the first time I used a higher lye concentration. Although I'd like to graduate to 40% lye concentration, since I'm adding something that might accelerate, I'm going to hold my horses for now....

I’ve looked at various discussions on this forum and elsewhere on the internet.

Based on a 3/18/2018 discussion and then a later 1/10/2021 discussion in which both @Amd and @DeeAnna participated, it seems that 1 % stearic acid will increase hardness without accelerating trace in too big of a way. I think @Amd did some comparison tests and settled on 1%.

I also understand that I should heat the hard oils (in particular the stearic acid) to about 160 ͦ to make sure the stearic acid melts. I usually melt all my hard oils in the microwave oven then add to the soft oils which I heat on the stove and finish heating them together (usually to 150F-160F.)

I saw recommendations for soaping “high” to avoid stearic spots. By “soaping” I assume this means the temperature of the oils when you combine the oils & lye water (not just how high you heat the oils.)

Soap Queen says “it needs a hotter soaping temperature (at least 160F.) Maybe she meant just heat the oil to that temperature but not actually combine with lye water at that temperature? In a discussion, someone refer to 100F as being soaping high as they usually soap at 70F (100F seems low to me.) Others recommended soaping at 120F to 130F.

So, I am wondering, what is a good temperature at which to combine the oils and lye water (which I think is what is meant by soaping?)

Also, I ordinarily add 2 tsp of sugar and 1 tsp of salt to my soaps (500 g of oil). I would like to also add 1 TBsp of colloidal oats.
Is the salt (which I add for hardness) PLUS the stearic acid too much? I have read that too much salt neutralizes the benefit of the sugar (to add bubbles.)
Will the combined salt & stearic acid neutralize the sugar?
Or, should I skip the salt?
I’m using stearic acid because I got it at a great price at a local craft shop (and I’m a sucker for a bargain…)

On stearic acid spots: I once got some white spots on my soap that was 32% palm oil. I think those were stearic spots. Even though it took them at least a couple weeks to show up.

Thank you in advance!!

 

[lsg]

IMO, your recipe contains too much Castor oil. Stearic acid can be trickly. Here is a link discussing the problem.
https://www.soapmakingforum.com/threads/how-to-use-stearic-acid-in-cp-soap.61104/

 

[akseattle]

@lsg, thank you. I went back and read the 2016 discussion started by Mikvahnrose who, I think is no longer on this forum. There were some good suggestions there. @Gingerbread2 said she’d been using 5% stearic acid for a few months with no acceleration problems. Unfortunately, she didn’t say what other oils she was using and/ or in what percentages. I am too chicken to even consider stearic acid at 5%, plus there are other oils that I want to use for their other properties.

But, I found a March 24, 2024 post by @BB25 . She had been combining oils & lye water at 55C or 131F. She asked the forum how low she could go. It doesn’t look like stearic acid is that common to use. No one responded with how much lower they went. @Becky1024 said she does hot process with stearic acid at 55C-65C.

@lsg, I see on the January 11, 2021 discussion, that you also have used stearic acid.
Can I ask, at what temperature do you combine your oils & lye water?

I was thinking I would try soaping at 131F , which is 55C. For my batches #5 through about #10, I had been soaping at 115F and once at 120F to avoid soda ash. I can’t remember why I started soaping close to 100F and trying to gel it with heat after being poured. So, I think I’m comfortable trying to work with batter at 131F. Higher than that starts to make me nervous. Plus, it seems like my FO might burn off!

Anyway, on your recommendation, I have reduced my castor oil to 9%. My usual recipe uses 8%. I can't positively say that's a good amount because I've only in the last month have my bars cured such that I can start trying them. (I want my bars cured for 8 weeks, at least.)

So, now my recipe is : lard 27%, coconut oil 20%, Tallow 14%, Shea Butter 4%, Stearic Acid 1%, Olive Oil 25%, and Castor oil 9%. 5% superfat and 38% lye concentration. I’m going to use a cranberry FO at 6% that should not cause acceleration. I’m going to color 20% of the batter with either Brazilian Clay or Rose Red Mica to just swirl in to give it little wisps of color - just enough to help me identify it as my stearic acid & colloidal oat experiment- but to not detract from the calmness that the colloidal oats should bring. [ This works in my mind's eye.... ]

Although someone on one of the discussions said “be generous with water so that you have time to work” I’m going to live on the edge and not reduce the 38% lye concentration.

Thanks for your help!! I’ll see how this works out!

 

[BB25]

@lsg, thank you. I went back and read the 2016 discussion started by Mikvahnrose who, I think is no longer on this forum. There were some good suggestions there. @Gingerbread2 said she’d been using 5% stearic acid for a few months with no acceleration problems. Unfortunately, she didn’t say what other oils she was using and/ or in what percentages. I am too chicken to even consider stearic acid at 5%, plus there are other oils that I want to use for their other properties.

But, I found a March 24, 2024 post by @BB25 . She had been combining oils & lye water at 55C or 131F. She asked the forum how low she could go. It doesn’t look like stearic acid is that common to use. No one responded with how much lower they went. @Becky1024 said she does hot process with stearic acid at 55C-65C.

@lsg, I see on the January 11, 2021 discussion, that you also have used stearic acid.
Can I ask, at what temperature do you combine your oils & lye water?

I was thinking I would try soaping at 131F , which is 55C. For my batches #5 through about #10, I had been soaping at 115F and once at 120F to avoid soda ash. I can’t remember why I started soaping close to 100F and trying to gel it with heat after being poured. So, I think I’m comfortable trying to work with batter at 131F. Higher than that starts to make me nervous. Plus, it seems like my FO might burn off!

Anyway, on your recommendation, I have reduced my castor oil to 9%. My usual recipe uses 8%. I can't positively say that's a good amount because I've only in the last month have my bars cured such that I can start trying them. (I want my bars cured for 8 weeks, at least.)

So, now my recipe is : lard 27%, coconut oil 20%, Tallow 14%, Shea Butter 4%, Stearic Acid 1%, Olive Oil 25%, and Castor oil 9%. 5% superfat and 38% lye concentration. I’m going to use a cranberry FO at 6% that should not cause acceleration. I’m going to color 20% of the batter with either Brazilian Clay or Rose Red Mica to just swirl in to give it little wisps of color - just enough to help me identify it as my stearic acid & colloidal oat experiment- but to not detract from the calmness that the colloidal oats should bring. [ This works in my mind's eye.... ]

Although someone on one of the discussions said “be generous with water so that you have time to work” I’m going to live on the edge and not reduce the 38% lye concentration.

Thanks for your help!! I’ll see how this works out!

Hey, I’ve played around with Stearic Acid quite a bit since March and found that actually I can go fairly low with the temp without it causing too much of an issue. My happy soaping temp is 40 degrees C which is about 104F and I don’t get stearic spots, or too much acceleration since I’ve got the right balance of FA….. but that took some time to achieve. With only 1% stearic acid I think you’d barely notice any acceleration, just slight change in consistency once you add to lye solution but stir through it and the batter will return to its fairly normal state as you’d expect….

 

[lsg]

I used stearic acid in a HP Pears soap dup. As I remember the stearic acid seized and I had to stick blend the paste while still heating. It took an effort, but turned out OK. I also use stearic acid in songwind's HP shaving soap recipe. As I remember, stearic acid starts to set up almost as soon as the lye solution is added to the oils. A lot of stick blending was required. If you can post a link to the conversation where I used stearic acid, that might help me remember the results.
Here is the recipe for the Pears soap dup.
Here is the ingredient list:

144 grams Castor Oil
144 grams coconut Oil
144 grams palm Oil
Few drops Vit. E.
18 grams stearic Acid
49 grams powdered pine rosin
72 grams sodium hydroxide
190 grams distilled water

Melt the solid oils, (I used a small crockpot insert and melted the solid oils in the microwave.) Melt stearic acid and pine rosin together with Castor oil in a microwave safe container. Add lye water to palm and coconut oils and blend to thin trace. Add stearic acid, pine rosin and Castor oil mixture and blend. As I said, the mixture will get very thick quickly. Put the lid on the crockpot and heat until mixture loosens up and looks like it is separating. Hit it again with the stick blender until it looks like a thick trace. Cook,
stirring every now and then, until mixture reaches Vaseline stage. Do a zap test. If there is no zap, add glycerin to the mixture and stir. Heat until all the paste is melted into the glycerin. Take off heat and add the FO and EO blend. Stir well and pour into mold. I used Bramble Berry's 12 bar mold.

After the cook add:
499 grams glycerin
3.4 grams cedarwood EO
3.4 grams lemon EO
3.4 grams rosemary EO
4 grams Fresh Pear FO

 

[akseattle]

My happy soaping temp is 40 degrees C which is about 104F and I don’t get stearic spots, or too much acceleration since I’ve got the right balance of FA….. but that took some time to achieve. With only 1% stearic acid I think you’d barely notice any acceleration, just slight change in consistency once you add to lye solution but stir through it and the batter will return to its fairly normal state as you’d expect….

@BB25 thank you for your response! it is really encouraging to see you soap so low without a problem, and it's encouraging that you think 1% stearic acid should be unproblematic. Can I ask you what your lye concentration is? My recipe will be 66% hard oils including the 1% stearic acid. Do you still think the 1% stearic acid should be totally fine?

 

[BB25]

@BB25 thank you for your response! it is really encouraging to see you soap so low without a problem, and it's encouraging that you think 1% stearic acid should be unproblematic. Can I ask you what your lye concentration is? My recipe will be 66% hard oils including the 1% stearic acid. Do you still think the 1% stearic acid should be totally fine?

I use a 40% lye concentration and have a 50% hard oils recipe. It’s such a low amount of stearic acid you will perhaps not even notice a difference. I did several trials using varying amounts and at 1% it was barely noticeable for me.

May I ask why you wish to include stearic? The reason I ask is because I use it as I am a palm-free/vegan soaper (mostly) and it was the best way to increase my FA profile to where I wanted it to be but if I was using a fat like lard or tallow I can’t see why I’d add it? My tallow bars were always as hard and long lasting (if not harder) than my vegan bars and it might be that you could get the FA profile you are looking for by increasing your tallow a little instead and then not worry about the fiddle of stearic? I try and keep my ingredients list as small as possible as there’s less room for error

But if you just want to use it to see what it does then I think you’ll be fine with 1% and pleased with the results.

 

[Firefly24]

I thought that stearic acid helps cut down on soap scum. We have hard water here where I live & soap scum is problematic. I want to try to use it too to see if the SA actually works for that.

 

[AliOop]

I thought that stearic acid helps cut down on soap scum. We have hard water here where I live & soap scum is problematic. I want to try to use it too to see if the SA actually works for that.

I've never heard that. Are you sure it wasn't citric acid that you heard about?

When citric acid combines with lye, it creates sodium citrate, which is a chelator, which will cut down on soap scum.

Citric acid requires a lye adjustment, so I use sodium citrate instead. It requires no lye adjustment and is an excellent chelator for my soaps. Dissolves easily in slightly warmed water before you add the NaOH.

 

[DeeAnna]

I agree with Ali -- I think you have your acids confused.

Stearic acid forms soap. Stearic soap is just as prone to making soap scum in hard water as any other type of soap.

Citric acid reacts with lye to form a chelator (citrate) that reduces soap scum.

 

[LynetteO]

I've never heard that. Are you sure it wasn't citric acid…?… I use sodium citrate instead. It requires no lye adjustment and is an excellent chelator for my soaps.

My most lovely lard soap recipe that I make for my family with DRY skin was created with recommendations/advice/words of wisdom from @AliOop and It’s a hard bar of soap. High Lard%/ Low CO%/RBO or Neem @ 15%/Castor oil @ 5% plus Sodium Citrate @1.5% oil PPO. I have never ventured into tallow.

 

[Firefly24]

I've never heard that. Are you sure it wasn't citric acid that you heard about?

When citric acid combines with lye, it creates sodium citrate, which is a chelator, which will cut down on soap scum.

Citric acid requires a lye adjustment, so I use sodium citrate instead. It requires no lye adjustment and is an excellent chelator for my soaps. Dissolves easily in slightly warmed water before you add the NaOH.

Yes, you are right, I had my acids confused. What ratio do you use? For example I need 130 grams of lye, I would use how much citric acid? Thanks @AliOop my brains is slow today.

 

[Firefly24]

I agree with Ali -- I think you have your acids confused.

Stearic acid forms soap. Stearic soap is just as prone to making soap scum in hard water as any other type of soap.

Citric acid reacts with lye to form a chelator (citrate) that reduces soap scum.

Yes I had them confused & thanks for the clarification.

 

[Firefly24]

My most lovely lard soap recipe that I make for my family with DRY skin was created with recommendations/advice/words of wisdom from @AliOop and It’s a hard bar of soap. High Lard%/ Low CO%/RBO or Neem @ 15%/Castor oil @ 5% plus Sodium Citrate @1.5% oil PPO. I have never ventured into tallow.

Please share the full recipe

 

[LynetteO]

Please share the full recipe

I tend to vary the CO anywhere from 15-23% depending on the user. My normal to dry skin can tolerate 23% CO, but for a friend with eczema I typically go with recommendation by @AliOop.

65%Lard; 15%Neem; 15%CO; 5% castor.

I substitute Rice Bran Oil for the Neem oil for friend(s) with just DRY skin that want a “scented” bar. Neem bars, I leave “unscented” & the neem smell fades quite a bit over time. Sodium Citrate added as a chelator at 1-1.5% PPO

 

[AliOop]

Yes, you are right, I had my acids confused. What ratio do you use? For example I need 130 grams of lye, I would use how much citric acid? Thanks @AliOop my brains is slow today.

I use sodium citrate now because no lye adjustment is needed for that. It also is great for making a nice cheese sauce.

But if you prefer to use citric acid, I recommend reading this article from DeeAnna's website that explains how to calculate the extra lye needed.

 

[Firefly24]

I use sodium citrate now because no lye adjustment is needed for that. It also is great for making a nice cheese sauce.

But if you prefer to use citric acid, I recommend reading this article from DeeAnna's website that explains how to calculate the extra lye needed.

Thank you!!! DeeAnna is one smart soaper!