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My vinegar is 4%, not 5%

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sebs

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Hello everybody! I hope someone can help me. I frequently use sodium acetate in my recipes (2% of my total oil amount). I always follow the instructions on this thread to calculate the amount of water to replace with vinegar and the extra NaOH. Now happens that my vinegar has 4% acetic acid and not 5%.

Does anyone have any ideas how to modify those calculations to obtain the same results with the type of vinegar I have?


I would greatly appreciate your help.
 

AliOop

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Wish I could help, but you don’t want me doing any math for you, haha. I think @DeeAnna will be your best source of help on this one.
 

DeeAnna

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Sodium acetate is the salt produced from reacting acetic acid with sodium hydroxide. It's not the same as vinegar (acetic acid).

Are you meaning to say you use sodium acetate AND vinegar (acetic acid)? Or are you just using sodium acetate? I'm confused.
 

earlene

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I believe she is talking about using vinegar that is 4% and not the oft-found 5%. I have also found 4% in some stores in the US. Not often, but yes, it's in some stores (I can't recall what state I was in when I saw it.) I have also seen 3%, which really surprised me.

PS, I see that 4% is what is available in some other countries (mentioned here), so perhaps that is why the OP only has 4% vinegar.
 
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DeeAnna

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I get that the vinegar is 4% -- no problem there -- but the OP also mentions sodium acetate, and I cannot figure out what's being added to the soap.

Is the OP adding sodium acetate in place of vinegar?​
Or is the OP adding sodium acetate AND vinegar?​
Or did the OP mentioning sodium acetate because that's what is created when vinegar reacts with sodium hydroxide, but is adding vinegar per the usual.​

That's why I'm confused.

Anyways, here's a step-by-step method for using vinegar that is 4% acetic acid --

How much lye does vinegar neutralize?

About 1 fluid ounce (2 tablespoons, 1 ounce by weight, or 28 grams) of 4% commercial vinegar contains 1.2 g acetic acid.​
1 oz by weight (28 g) of commercial 4% vinegar neutralizes about 0.8 g NaOH.​
1 oz by weight (28 g) of commercial 4% vinegar neutralizes about 1.12 g KOH.​

How to calculate the extra lye?

When using vinegar in your recipe, add the appropriate extra weight of lye needed to react with the acid. If you do not add any extra lye, the acid will increase the superfat in your soap.​

Sodium hydroxide, NaOH
Decide how much vinegar to use. If you aren't sure, I suggest using commercial vinegar for half of the water in your recipe.​
For example, if a recipe calls for a total of 200 grams of water, use 100 grams of vinegar and 100 grams of water.​
NaOH for 4% vinegar, grams = Vinegar, grams X 1 / 28 X 0.8 = 0.0286 X Vinegar, grams​
Total NaOH, grams = NaOH for vinegar, grams + NaOH for saponification, gram​

As Earlene mentioned, vinegar sold in the US is typically 5% acetic acid. Here's my step-by-step for 5% vinegar -- Soapy Stuff: Acetic acid (Vinegar)
 

Marsi

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Does anyone have any ideas how to modify those calculations to obtain the same results with the type of vinegar I have?
multiply the vinegar amount by 1.25

(alternatively multiply the vinegar amount by 5 and divide by 4)

use the revised vinegar amount to adjust your water
 

sebs

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Thank you very much for all your responses. @DeeAnna , your third option is correct: i just add vinegar per the usual. The SA that i was talking about is the one that is created as the result of the reaction with the lye. I´m currently living in Uruguay (Southamerica) and here vinegar is typically 4% acetic acid. The brand Heiz, which is 5%, is available here but it is super expensive...

I definitely will need some time to study and make sure that i figured out all this information that you so gently have privided to me. Specially when math is not my cup of tea haha

@Marsi If i dont get you wrong, you are telling me that i have to keep all the calculations the same as if i had a 5% vinegar, but adjusting the vinegar amount. I only have to multiply the vinegar amount by 1.25 and adjust the water amount accordingly. The extra lye amount does not change. Am i right?
 

Marsi

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If i dont get you wrong, you are telling me that i have to keep all the calculations the same as if i had a 5% vinegar, but adjusting the vinegar amount. I only have to multiply the vinegar amount by 1.25 and adjust the water amount accordingly. The extra lye amount does not change. Am i right?
yes you are right
the extra lye amount does not change

multiplying your 4% vinegar by 1.25 increases the amount of acetic acid to match the 5% calculation
the same amount of extra lye is used in both the 4% and the 5% calculations

we also have 4% vinegar in australia and some are 6%
I havent found a 5% vinegar yet
 
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DeeAnna

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Thanks for explaining, @sebs!

Marsi's approach works best if you have a recipe based on 5% vinegar and you want to adapt that recipe to 4%. It answers the question, "How much 4% vinegar is needed to get the same weight of acetic acid as a recipe based on using 5% vinegar?"

My method works best if you don't already have a recipe based on 5% vinegar -- you're starting from scratch with the 4% stuff.
 

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