Combining Acids in Soaps

[Kiran]

Dear Seniors,

I am new here and to soaping so i am using this forum to learn the art of soap making that this forum has turned into a proper science. I appreciate that - being a man who does not like to approximate quantities and possibilities.

And i understand that Acetic Acid (@2%) hardens soap like Lactic Acid and Citric Acid (@2%) helps reduce chances of Rancidity and also with Soap Scum.

But i am yet to read something on the possibility of a combination of acids in Soaps, like Acetic acid and Citric acid together? Does it help of since both form salts, will it make the soap brittle? Will the salts react with each other to change the above mentioned properties?

This though came across my mind because my first batch of 100% olive oil, with 5% super fat, started to go rancid in about 2 months time (wanted to cure it was a year ) . The soap is still soft and melts away quite fast when in contact with water. Hence in order to counter both these issues i thought it was best to add both Acetic Acid and on Citric Acid. But can it be done and will it help me achieve what i want to here?

Any and all help will be gladly received.

Kind regards, Thomas

 

[earlene]

I wonder if we can get senior discounts from soap supply vendors! Now there's a thought! I get senior discounts at lots of places, when I remember to ask, but have never thought to ask online vendors.

Welcome, Thomas!

To address your questions: Yes, I have used vinegar (contains acetic acid) in soap and it can, when used at too high a percentage cause brittleness. You also have to alter your calculations as the acid interacts with the lye, changing the amount of available lye to interact with the oils. There are threads here at SMF that address how to calculate for adding vinegar, as well as for adding citric acid. Some may use straight acetic acid as well, and of course you could use too much, but you still have to alter the amount of lye in your calculations.

As for your 100% Olive oil soap becoming rancid so quickly before it ever had a chance to complete its cure, there are several factors that could have contributed to the rancidity. The oil could have been too old to start with; other unknown factors (purity of your lye, type of water used, accuracy of your scale, how you stored your curing soaps, other unknown contaminants) may also have contributed. Fresh oil, accurate scale, clean (very clean) working conditions, 'pure' lye (without contaminants), distilled water (as opposed to tap or water from questionable sources), use of lye safe materials in manufacture and curing (no metals other than high-grade stainless steel), adding ROE to the oils, and avoiding touching the soap with bare hands (use clean gloves, not only to protect yourself, but also the soap) all contribute to prevent DOS.

ROE is Rosemary OleoResin, and when added to fresh oils when you first open the bottle will help ward off DOS. Accurate measurements and the proper amount is important. See these two links for more information about the use of additives to prevent DOS (the rancidity you experienced is often referred to as DOS - dreaded orange spots):

http://cavemanchemistry.com/DreadedOrangeSpot-Dunn.pdf
https://classicbells.com/soap/ROE.html

In fact, you will find a lot of great resource information at classicbells here: https://classicbells.com/soap/soapyStuff.html
as well as here at SMF.

 

[Steve85569]

The problem I have had by adding acetic ( sodium acetate) , citric ( sodium citrate) and other salts together in a recipe is that adding too many salts tends to speed up most of my recipes and then there's the soda ash ( salt on the out side of the soap) that happens. Very small amounts of one or two salts do not cause this problem (2% or less).
My limited experience is that if I use a low "superfat" ( lye discount) I have less oil left over in my soap and less tendency to get DOS. I typically now use a 0% superfat for pure olive oil soaps . With the long cure they don't zap. I do zap test them.

 

[Saponomancer]

I use vinegar(acetic acid) and citric acid in my soaps all the time! My recipes are a bit speedy, although most of the time I have just enough time for a drop swirl or an itp swirl, if the fragrance behaves. I haven't had a problem with dos since I started using the citric acid. (I do account for all acid amounts in my lye calculations). No soda ash here.

 

[Kiran]

Welcome, Thomas!

---- Thank you Earlene!

there are several factors that could have contributed to the rancidity.

---- That is a comprehensive list that i need to follow to the T, and i think i found the culprit as well.

distilled water (as opposed to tap or water from questionable sources),

----- I used tap water as against disstilled water, which might have been the cause of my troubles.

http://cavemanchemistry.com/DreadedOrangeSpot-Dunn.pdf
https://classicbells.com/soap/ROE.html

In fact, you will find a lot of great resource information at classicbells here: https://classicbells.com/soap/soapyStuff.html
as well as here at SMF.

----- Thanks for the reads i will go through them and further educate myself.

The problem I have had by adding acetic ( sodium acetate) , citric ( sodium citrate) and other salts together in a recipe is that adding too many salts tends to speed up most of my recipes and then there's the soda ash ( salt on the out side of the soap) that happens. Very small amounts of one or two salts do not cause this problem (2% or less).
My limited experience is that if I use a low "superfat" ( lye discount) I have less oil left over in my soap and less tendency to get DOS. I typically now use a 0% superfat for pure olive oil soaps . With the long cure they don't zap. I do zap test them.

------- That is interesting Steve, so only issue you faced was acceleration just as theDragonGirl does. But is 0% super fat slightly risky of ending up with a lye heavy soap? would you recommend adding a .5 or 1% CO to be on the safe side? and also because CO is less prone to DOS?

I use vinegar(acetic acid) and citric acid in my soaps all the time! My recipes are a bit speedy, although most of the time I have just enough time for a drop swirl or an itp swirl, if the fragrance behaves. I haven't had a problem with dos since I started using the citric acid. (I do account for all acid amounts in my lye calculations). No soda ash here.

----- TheDragonGirl this is great news that you have been doing this for a long time and it is resulting in a stable desirable product. But you do add additional Lye to make up for the Acetic and Citric acids i assume. Also what super fat do you tend to use generally?
I will use distilled water, try playing around with my Lye concentration and super fat% to get a good basic recipe and then add these additives and let you know what i come across. But this is encouraging, Thanks a bunch.

 

[Saponomancer]

----- TheDragonGirl this is great news that you have been doing this for a long time and it is resulting in a stable desirable product. But you do add additional Lye to make up for the Acetic and Citric acids i assume. Also what super fat do you tend to use generally?
I will use distilled water, try playing around with my Lye concentration and super fat% to get a good basic recipe and then add these additives and let you know what i come across. But this is encouraging, Thanks a bunch.

I do calculate out the extra lye I need yes! I use a 5% superfat. Distilled water is always a good idea, as well.

 

[Steve85569]

I use 4 to 6 % lye discount so I'm not using a 0% SF. Even if I was I am fairly certain that my lye is never 100% pure - it usually runs 98% or less just because of the nature of the material. The exception to this is laundry soap where I actually calculate a negative lye discount( 3 or 4%) for degreasing in the laundry.

The only times I had soda ash problems I was over indulging in vinegar and citric ( thinking more is better) so 2% for citric and using vinegar as half of the liquid works great. Using the vinegar at that rate gives an approximate rate of 2.4% sodium acetate.

If I remember correctly I was getting ash when I was in the range of 9% or so total salt ( sodium "x" ) additives.

 

[Kiran]

I do calculate out the extra lye I need yes! I use a 5% superfat. Distilled water is always a good idea, as well.

Thanks TheDragonGirl your time and the data are much appreciated.
Have a good day.

Kind regards, Thomas

 

[Kiran]

I use 4 to 6 % lye discount so I'm not using a 0% SF. Even if I was I am fairly certain that my lye is never 100% pure - it usually runs 98% or less just because of the nature of the material. The exception to this is laundry soap where I actually calculate a negative lye discount( 3 or 4%) for degreasing in the laundry.

The only times I had soda ash problems I was over indulging in vinegar and citric ( thinking more is better) so 2% for citric and using vinegar as half of the liquid works great. Using the vinegar at that rate gives an approximate rate of 2.4% sodium acetate.

If I remember correctly I was getting ash when I was in the range of 9% or so total salt ( sodium "x" ) additives.

That is a point to ponder, so even though we use a 5%SF that WILL actually translate to a 7% Lye discount.
Yes 9% sure sounds quite High. I tired 2% SA after reading all the advice and suggestions here and it has turned to be a easily unmoldable and hard soap, but i am waiting for the cure to complete to report back on this post.

Thanks for your time Steve.

Kind regards, Thomas

 

[Steve85569]

And for an informative read:
https://www.soapmakingforum.com/threads/how-to-use-vinegar-to-harden-your-soap.59295/

 

[Kiran]

And for an informative read:
https://www.soapmakingforum.com/threads/how-to-use-vinegar-to-harden-your-soap.59295/

Thanks for the the read Steve.
I had gone through this one earlier, and Murry, TeresaT and DeeAnna are awesome.
Inspired, i translated that information into an XL which MIGHT help the larger audience here.

Can I upload a XL sheet to a post on this site?

Kind regards, Thomas

 

[cmzaha]

I soap with a 50/50 lye solution and use vinegar as the remaining water replacement. Superfat at 2%. I add in the extra lye necessary to react with the vinegar and I do not find it accelerates my trace at all, nor do my soaps become brittle. I use BHT and EDTA to counter dos, especially in my recipe that contains lard, even though my brand of lard already contains BHT. I do not get does but it does not stop the old smell in an old soap that can happen with milks and lards.

 

[zanzalawi]

@cmzaha do you add additional bht or stick with what is already in your lard?

 

[cmzaha]

I add additional bht 0.01%-.1% so just a tiny amount. I usually add in 0.05% depending on how much lard is in my recipe, which is normally 25%

 

[zanzalawi]

I LOVE lard heavy soaps, so I best get myself some bht [emoji1] thank you!

 

[Steve85569]

Spreadsheets are a no go on most forums. Malware potential is too great.

I am using a short formula I use to convert a gallon of vinegar at a time to water and SA. I simply react the 5% acetic with Sodium hydroxide. The results are stored in the fridge in the vinegar bottle.
Works very well and the exothermic reaction has been done with the acetic.