Citric Acid Use

[Zany_in_CO]

Citric Acid can be used as a chelating agent (like sorbitol, sodium lactate, sodium gluconate) and is used to reduce soap scum, especially useful if you have hard water. It reacts with the lye to form sodium citrate.

Use rate is 0.1% to 0.5%. Up to 1 tsp. (1-5 grams) ppo
SAP value is 0.571 for monohydrate citric acid.
SAP value is 0.625 for anhydrous citric acid.

Add citric acid to oils before adding lye water. If you add it to your water, add the lye slowly and carefully. The citric acid will cause some excess bubbling and splashing.

When using CA in your soap...you have to add a bit of extra lye to compensate for the oils that the CA brings out of the batter...CA counteracts lye, so to make up for that, I add 0.571 oz of lye for every oz of citric acid.

so if you are using 0.25 oz of citric ppo...and making a 32 oz batch of soap:
2 (lbs) x 0.25 = 0.5 oz CA
0.5 x 0.571 = 0.2885 oz extra lye (i would use 0.3 oz)

 

[SideDoorSoaps]

[QUOTE="Zany_in_CO, post: so if you are using 0.25 oz of citric ppo...and making a 32 oz batch of soap:
2 (lbs) x 0.25 = 0.5 oz CA
0.5 x 0.571 = 0.2885 oz extra lye (i would use 0.3 oz)[/QUOTE]

I did this the other day but in grams and used 2% ppo ... now I wonder if I used too much CA and not enough NaOH

my recipe is 64 oz of oils (1814.4 grams)
So I added 36.28 gm of CA (1814.4 * .02) and 5.8 gm of extra NaOH (36.28/6.24)

if I went by yours 64 oz
4 (lbs) x .25 = 1 oz (28.35 gm) CA
1 x .571 = .571 oz (16.18 gm) NaOH

so will I have too much super fat? I usually do 5%. This is so much math!

 

[SideDoorSoaps]

[QUOTE="Zany_in_CO, post: so if you are using 0.25 oz of citric ppo...and making a 32 oz batch of soap:
2 (lbs) x 0.25 = 0.5 oz CA
0.5 x 0.571 = 0.2885 oz extra lye (i would use 0.3 oz)[/QUOTE]

I did this the other day but in grams and used 2% ppo ... now I wonder if I used too much?

my recipe is 64 oz of oils (1814.4 grams)
So I added 36.28 gm of CA (1814.4 * .02) and 5.8 gm of extra Naoh (36.28/5.8)

if I went by yours 64 oz
4 (lbs) x .25 = 1 oz (28.35 gm) CA
1 x .571 = .571 oz (16.18 gm) NaOH

 

[Steve85569]

The main reason to not use higher amounts of CA is that it does tend to soften the finished soap resulting in a bar that does not last as long.
I routinely use CA at 2% - but my recipe's have been adjusted over time to help compensate for the increase in soluability of the soap.

I will also add the CA to the liquid and then add a small amount of NaOH to react the CA prior to adding in the rest of the NaOH.

 

[Zany_in_CO]

Link to DeeAnna's Soapy Stuff on Citric Acid

 

[DeeAnna]

The link to my article on citric acid is this one -- https://classicbells.com/soap/citricAcid.asp

You can use the SoapMakingFriend calculator to do this math for you. See https://www.soapmakingfriend.com/

Put the fat weights into the calc. Then choose citric acid as a custom additive. When you add it to your recipe, the calc will suggest a citric acid weight based on 2% of your total fat weight. You can either stick with that number or change it. If you want 1% citric acid, cut the amount in half, for example.

The calc will then calculate the extra NaOH needed to neutralize the citric acid. The extra NaOH is included in the total NaOH weight.

 

[SideDoorSoaps]

The link to my article on citric acid is this one -- https://classicbells.com/soap/citricAcid.asp

You can use the SoapMakingFriend calculator to do this math for you. See https://www.soapmakingfriend.com/

Put the fat weights into the calc. Then choose citric acid as a custom additive. When you add it to your recipe, the calc will suggest a citric acid weight based on 2% of your total fat weight. You can either stick with that number or change it. If you want 1% citric acid, cut the amount in half, for example.

The calc will then calculate the extra NaOH needed to neutralize the citric acid. The extra NaOH is included in the total NaOH weight.

Thanks, @Zany_in_CO. I got a bit confused.

sorry, I didn’t mean to post twice. Somehow I was booted from SMF and then I looked for my post and it wasn’t there and posted it again.

I didn’t even think of the new program, thank you. I was hand mathing :/ I kept referring back to your page @DeeAnna and asking myself if I was doing it right. It was kinda aggravating. I’m not too great in math. Now I’m off to recalculate my recipe!

@Steve85569, my soap recipe is very hard and lasts forever so it could take a bit of softening, I wasn’t worried about that.

 

[SideDoorSoaps]

So I got it figured out! Yay! I definitely used the right amount of CA for my batch size but needed 13 grams of additional NaOH but that’s not too bad since it just adds a bit more to my SF. I went wrong in not considering every 10 gm of CA for 6.24 NaOH correctly.

In any case, I can’t wait to try this soap and see how the soap does in my hard water and reducing soap scum.

 

[cmzaha]

I like a combination of Tetrasodium EDTA and Sodium Gluconate to cut soap scum at a rate of 0.5% each. I found Citric acid would for crystals on the outside of my soaps which annoyed me, although it did not hurt anything.

 

[SideDoorSoaps]

I like a combination of Tetrasodium EDTA and Sodium Gluconate to cut soap scum at a rate of 0.5% each. I found Citric acid would for crystals on the outside of my soaps which annoyed me, although it did not hurt anything.

How long did it take the crystals to show up?

 

[cmzaha]

Sorry, I do not remember. Maybe 3 or 4 months. DeeAnna might remember.

 

[DeeAnna]

All I remember is it took a little while, Carolyn, but I don't remember how long. Reducing the citric acid to no more than 2% seemed to solve this issue for people who prefer to use citric acid / citrate.

 

[cmzaha]

I was just checking back in some notes and 2.9% formed crystals.

 

[SideDoorSoaps]

I was just checking back in some notes and 2.9% formed crystals.

Was that with it without accounting for NaOH neutralizing?

 

[cmzaha]

Was that with it without accounting for NaOH neutralizing?

I always use extra NaOH when adding acids. If using Citric Acid I add in extra NaOH at the rate of 0.624 x the amount of added citric acid.

 

[DeeAnna]

"...Was that with it without accounting for NaOH neutralizing?..."

Whether or not you add extra NaOH, it doesn't make any difference to the citric acid. Citric acid will always to react with all of the NaOH it wants to react with.

Whether Carolyn added extra NaOH or not, her soap still had a full dose of citrate that would form by adding 2.9% citric acid. By adding extra NaOH along with the citric acid, she ensured her superfat stayed correct.

But maybe I'm misunderstanding your question?

 

[SideDoorSoaps]

"...Was that with it without accounting for NaOH neutralizing?..."

Whether or not you add extra NaOH, it doesn't make any difference to the citric acid. Citric acid will always to react with all of the NaOH it wants to react with.

Whether Carolyn added extra NaOH or not, her soap still had a full dose of citrate that would form by adding 2.9% citric acid. By adding extra NaOH along with the citric acid, she ensured her superfat stayed correct.

But maybe I'm misunderstanding your question?

just my thinking and trying to understand the whole chemistry of it...I didn’t know if the SF had anything to do with more citric acid/sodium citrate and crystal formation.

in my calculations, I definitely added the full 2% of citric acid but not enough to counteract the extra super fat.

 

[DeeAnna]

I wouldn't think extra superfat would make a lot of difference, but I've not tested that to know absolutely for sure. The layer of haze or crystals on the outside of the soap seems to be more related to the % of salts in the soap. More salts => more likely to get crystals/haze

 

[SideDoorSoaps]

So it doesn’t matter how much NaOH and CA there is because it all turns into sodium citrate?

 

[DeeAnna]

"...So it doesn’t matter how much NaOH and CA there is because it all turns into sodium citrate?..."

It's chemistry, so a person does have to pay attention to the amounts. The relative proportions of NaOH and citric acid do matter.

But if I assume you're talking about a normal soap making scenario, there will always be a lot more NaOH present than is needed by the citric acid. In this case, all of the citric acid will always turn into sodium citrate.

Your posts (14 and 19) have been rather cryptic, so I'm not entirely sure if I'm answering the real question you're asking. I'd feel more comfortable if you'd provide a little more of your reasoning behind these brief questions.