- Dec 6, 2014
- Reaction score
Anyone ever use potassium carbonate for liquid soap instead of potassium hydroxide? And how you calculate the amount to be use?
Potassium carbonate is an additive for liquid soap -- it makes the soap base easier to stir during the cook and helps speed things up during the dilution phase. I've tried it and it works. Here's a bit of info on use:
(KCO2) CAS# [584-08-7]
Use: 2% - 2.5% ppo
Add to lye solution
Thoroughly dissolve 2% Potassium Carbonate in hot lye solution. If you choose this option, you will need to add 1.7% Borax or Citric Acid to your dilution water to neutralize the Potassium Carbonate. (See Failor pp: 11, 23, 28.)
It is actually what old soap was made from when it was made from wood ashes.
^^^^^ Ditto. Thank you for adding that, DeeAnna, I should have mentioned that I did HP in the crockpot. Worked like a charm, both for easier stirring and for quicker dilution. At least, that was my experience.The soap needs to be made using a boiled method or possibly a hot process method -- you can't do carbonate saponification via cold process.
In recent times, a carbonate solution (either potassium carbonate or sodium carbonate or both) was converted to the hydroxide form by reacting the carbonate with slaked lime. The resulting hydroxide solution was used to make the soap.
There are some older recipes for making household soap that claim the soap is made without "lye" (with "lye" in this case meaning sodium hydroxide). What they're doing is reacting sodium carbonate (washing soda) with lime to make the sodium hydroxide solution. It's possible that this is what your neighbor's grandmother did.
You can make soap with the carbonate if you want to, but you will have to cook the soap for some time to drive the saponification reaction. The soap needs to be made using a boiled method or possibly a hot process method -- you can't do carbonate saponification via cold process.
Most soap makers shifted away from carbonate saponification method in the 1700s and early 1800s if they had the ability to treat the carbonate solution with lime to turn it into a hydroxide solution -- saponifying with the hydroxide solution is easier and more reliable.
Honestly, if you have any other use for the potassium carbonate, you should use it that way.
^^^^^ Ditto. Thank you for adding that, DeeAnna, I should have mentioned that I did HP in the crockpot. Worked like a charm, both for easier stirring and for quicker dilution. At least, that was my experience.
PS: If anyone wants some Potassium Carbonate to experiment with, I have plenty to share! PM me.
I am asking about the saponification DeeAnna but maybe I can use it as additives too.You asked about using potassium carbonate to make liquid soap. Did you mean to use it as an additive like Zany is suggesting? Or as the main alkali for saponification as I have assumed? What Zany is saying about how to use potassium carbonate and what I am saying are two different uses for this chemical.
You could do a cold process liquid soap if using potassium carbonate per Zany's suggestion, since the potassium carbonate in this case is not the alkali for saponification.