Use Fatty Acids in soap

[Moonday]

Hi
Can I use of fatty Acids in my soaps instead some oils? For example can I remove tallow and add Palmitic Acid instead if lye calculator account it correctly?
Thank you for your respond

 

[DeeAnna]

Yes, you can. Be aware that fatty acids react very quickly with lye. The soap batter may seize (thicken up instantly) after the fatty acids and lye are mixed together. More fatty acid in the recipe increases the chance of seizing.

The cold process method may not work very well with soap that seizes, so you may have to use a hot process method. Do not expect to have a thin batter and enough time to make fancy designs until you understand how the soap will behave.

Also the fatty acids will not add glycerin to the soap. That may or may not be important to you, but it is something to keep in mind.

 

[Moonday]

Is any way to add for example solid stearic acid to an oil and use it in my receipts?

 

[DeeAnna]

"...add ... solid stearic acid to an oil..."

Um, well ... I am not sure exactly what you mean by this.

If you mean that you want to add the solid stearic acid to oil or fat for future use -- No, that will not work. Stearic is a very firm solid at room temperature. It will be nearly impossible to blend solid stearic into liquid oil. You will have to melt it first. Stearic melts at a higher temperature than regular soaping fats, so you would also want to warm the oil as well. That will help the stearic remain liquid long enough to mix in properly. Blend the liquid stearic thoroughly into the warmed oil. I have not personally done this. With some experimentation, you may find a method that works well.

If you mean that you want to add the stearic acid to oil or fat at the time you make the soap -- Yes, you can, but you will again have to melt it. You cannot add solid stearic to the soap without causing problems. I normally add the stearic at "trace" after the lye has been mixed into the warmed oils and the batter is emulsified. Again, if you do not get the stearic mixed in well before it solidifies, you will get small waxy spots of stearic in the finished soap.

In either case, if you don't mix the melted stearic into the oil or soap batter thoroughly enough, the stearic may solidify into small particles. These particles will not saponify and will create hard waxy spots in the finished soap.

 

[CaraBou]

Soaping with fatty acids rather than with plant and animal oils that contain them is a novel concept to me. I didn't realize they were readily available to buy, for one thing. I did know about stearic I guess, but not the other ones common in soap. Do they still look like an oil? Are they more expensive than oils?

 

[Moonday]

 

[Moonday]

This is some sort of industrial Stearic Acid that melt in 158 F. Test it in soap making wasn't useful! this is very uncontrolled material and result was very unusable! May be useful for HP! Price is near every 2.2 pound as 3 US Dollar where similar Coconut oil price is 7.3 US Dollar!
I hope I arrive to better result by Lauric Acid or Miristic Acid.
I have a problem about obtain Palm oil or tallow or lard. I test some sort of tallow of Camel but wasn't useful (There isn't any correct search on it for saponification)! So I'm thinking to use of fatty acids.
If I arrive to useful result I will report to you and if anybody have any experience with them please tell me too!
Thank you DeeAnna! you are really a professional!

 

[DeeAnna]

"...industrial Stearic Acid that melt in 158 F. Test it in soap making wasn't useful! this is very uncontrolled material and result was very unusable! May be useful for HP! ..."

That sound very much like the stearic acid that I use in shave soap. It is often used in cream soap as well. As long as a person knows how to handle it properly, it is useful and usable.

Any ... ANY ... fatty acid will react almost instantly with lye. Do not expect lauric or myristic acid to behave any differently than this stearic acid. You will need to use a hot process method if you add more than a small amount of any fatty acid to your soap. It is just the nature of the beast.

 

[DeeAnna]

CaraBou -- fatty acids from stearic on down (shorter chain) are solids at room temp and oleic acid and up (longer chain) are liquids. Not sure about price -- I've only bought commercial stearic (actually it's a blend of stearic and palmitic) for use in shave soaps and lotions.

 

[Dr.J]

CaraBou -- fatty acids from stearic on down (shorter chain) are solids at room temp and oleic acid and up (longer chain) are liquids.

The melting point of the saturated fatty acids actually increases with chain length:

FA Tm
C12 43.2C
C14 54.4C
C16 62.9C
C18 69.3C
C20 75.5C

I think you meant to say that its the unsaturation in the oleic, linoleic, and linolenic acids (all C18 length) that leads to lower melting points (hence liquids at room temp):

C18:1 14C
C18:2 -5C
C18:3 -11C

 

[DeeAnna]

Yes, you are correct. I was thinking about the fatty acids most commonly found in soaping fats. Lauric, myristic, palmitic, stearic, oleic, linoleic, linolenic.