Using citric acid?

[Obsidian]

For those of you use citric acid in your soap as a chelating agent, how to you add it?
First time I added the powder into the cool lye solution and didn't care for the chemical reaction, this time I mixed it with a little water and then added that to the lye but it still reacted more then I like.

Would it be better to dissolve it in water and add at trace?

 

[IrishLass]

If you are going to use it as a chelating agent, I would use Sodium Citrate as opposed to citric acid (they are 2 different things). The recommended use for sodium citrate is .1% as per your oil weight.


IrishLass

 

[Obsidian]

I already have the citric acid though and don't really want to buy another additive. I only use it once in awhile, hoping it might help with soap scum.

 

[TVivian]

From what I'm reading you dissolve 1 part citric acid to 4 parts water then add the mixture at 1% of your oil weight at trace. I have not tried it and now I'm anxious to. I'm assuming that adding more than 1% would neutralize the lye? Thanks for this question because I learned something new that it want to try!

 

[TVivian]

I really hate the scum.

 

[Lindy]

Basically what you are doing when you add citric acid to your soap is increasing your superfat because of the lye being neutralized.

 

[DeeAnna]

Citric Acid + NaOH => Sodium citrate + H2O (water) + Heat

For the math whizzes out there: 1 g citric acid neutralizes 0.624 g NaOH
A simpler version for the rest of us: 10 g citric acid neutralizes 6 g NaOH

Figure the lye needed to saponify your fats. Decide how much citric you want to use in the soap. Figure the lye needed to neutralize the citric acid.

Total lye to use = Lye for saponification + Lye to neutralize citric acid

I would take this approach -- Measure out the water that you want to use to make the lye solution. Mix the citric acid into this water. Add the lye slowly to the water and stir as you go. This will give you more control over the speed at which the lye and citric acid react.

 

[CaraBou]

^^^Yep, dissolve the CA in your water first, and then add the lye. I've only done it once, but I didn't get any fizzies, smell or color change.

I will restate a 2-part formula I had found back then that gives the ratios simply and clearly:
10 g citric acid for every 1,000 g oils
6 g extra lye for every 10 g citric acid

My CA soap is about 2 1/2 months old -- almost time to use it. Actually, it's my avocado soap. I plan to retrieve it during the tragic depths of winter!

 

[Obsidian]

^^^Yep, dissolve the CA in your water first, and then add the lye. I've only done it once, but I didn't get any fizzies, smell or color change.

I will restate a 2-part formula I had found back then that gives the ratios simply and clearly:
10 g citric acid for every 1,000 g oils
6 g extra lye for every 10 g citric acid

My CA soap is about 2 1/2 months old -- almost time to use it. Actually, it's my avocado soap. I plan to retrieve it during the tragic depths of winter!

Ok, I'll do it this way next time, thanks.

Thats the same formula I use, its simple for a math challenged person like me to figure out lol.

 

[DeeAnna]

"...6 g extra lye for every 10 g citric acid..."

I want to add a caution about the generic use of the word "lye". In today's usage, "lye" often means NaOH, but it can also just as easily mean KOH. Depending on the mindset of the readers and how carefully they read this thread, they might possibly misinterpret and think this applies to KOH as well.

The KOH version is 8 g KOH to neutralize 10 g citric acid.

 

[Lindy]

I have to admit to not having tried this and I am trying to wrap my head around it. What is the purpose of adding citric acid when it is neutralizing lye? Is there a benefit that I am missing?

TIA

 

[coffeetime]

The sodium citrate that is formed acts as a chelator for minerals in hard water.

 

[Lindy]

Thanks Coffeetime

 

[CaraBou]

Just to take it a step further for those uncertain why they might want a chelator in hard water... to reduce soap scum and make more lather.

 

[The Efficacious Gentleman]

Out of interest, does it help that "squeeky clean" feeling that one can get with handmade soaps in hard water?

The Admirable Lady uses citric acid when making cordials such as peppermint. I might try 1% in the next shaving soap trial......................

 

[Obsidian]

I haven't noticed a difference in the skin feel at all but I do see reduced soap scum which is great.

 

[CaraBou]

Obsidian, have you noticed any improvement in lather? I hear that the extra calcium in hard water plays a dirty switcharoo with the soap salts to produce scum and to rob the soap of lather. I'm not sure I'll be able to tell with my CA batch b/c I don't have a control to compare it against. Also, the recipe I used it in has all kinds of stuff going on in it (avocado, cuc, +) so I really have no hope of telling. Hmmm... I should make more soap so I can assess the situation better

 

[Obsidian]

You know, I don't really have anything to compare it to either. Both soaps I used it in are high lard specialty soaps. I should make a control batch, just to see if their is much of a difference.

 

[DeeAnna]

"...does it help that "squeeky clean" feeling that one can get with handmade soaps in hard water?..."

"...have you noticed any improvement in lather? I hear that the extra calcium in hard water plays a dirty switcharoo with the soap salts to produce scum and to rob the soap of lather...."

Magnesium and calcium ions in hard water will react with our lovingly made sodium (or potassium) soap. The result of this reaction are calcium and magnesium soaps aka "hard water scum". These soaps are insoluble in water and an uncomfortable sticky feeling on the skin. They make the gray ring in the bathtub and rough, dull deposits in the corners of the shower.

By adding sodium citrate, the lather and skin feel might improve or might not, depending on how hard your water is.

 

[Soap Techniques]

I do see reduced soap scum which is great.

Obsidian, how much citric acid (or sodium citrate) are you using?