Citric Acid + NaOH

[new12soap]

In another thread about using different citrus juices in soap, someone commented that adding citric acid to soap will react with lye and create sodium citrate.

Is there an easy way to determine how much citric acid would be needed to produce how much sodium citrate? In other words, let's say I am making a 1000g (weight of oils) batch of soap, and I want 0.1% sodium citrate (also by weight of oils) in my soap. How much citric acid would I need to add to accomplish that? And how much lye would it steal to do it? By what amount would my lye be reduced? Enough to need to decrease my superfat? Even if I wanted a higher percentage of sodium citrate?

Really not looking to add fuel to any fires, just wondering if it would be more cost effective to use citric acid than sodium citrate! If I have to use 3 times the amount of citric acid as sodium citrate then no, it probably isn't, but 1:1 or even 1.5:1 then maybe...

TIA

 

[Lindy]

I wish I knew the answer to that. From what I am seeing (& again I am so not a scientist, just a soapmaker) if you are wanting to use citrus juice in your soap perhaps look at which one you want to use and how strong (acidic) it is then go from there. For instance, if I understand this right, Lemon & Limes are the stronger in acid, Grapefruit is lower and then oranges. From what I've been reading, the sweeter the fruit, the less citric acid is in there.

I like how you're thinking - using citric acid instead of the fruit, at least that is how I am reading it. Am I correct in that assumption?

ETA For me it was more about the novelty of using citrus fruit for soap and I'm not done playing with it yet.....

 

[new12soap]

My idea was that adding citric acid powder would create sodium citrate, which together with bht can help ward off DOS. But I don't know how much citric acid plus how much lye would equal how much sodium citrate to make sure I end up with the correct amount based on my batch size. Citric acid costs a lot less than sodium citrate costs, but then you need to know how much lye it takes for the conversion and if it is enough to affect the superfat...

I remember reading some time ago (I am sorry, I don't recall where) about a soaper that was experimenting with using apple cider vinegar as the liquid to try to make a milder soap, and the end result barely affected the pH of the finished soap at all! So now I find myself thinking how nice a little citrus in soap would be... but again, if the citric acid would give the same end result...

Anyway, thanks for the response