Preferred Chelating Agents

[JillGat]

Sodium gluconate is phenomenally expensive in Australia. So I use ctric acid which is AU$7 (US$4) a kilo (35oz).

Is citric acid an effective chelator?

 

[DeeAnna]

Is citric acid an effective chelator?

Citric acid as citric acid is NOT a chelator. When citric acid reacts with an alkali such as sodium hydroxide, the two form the chemical sodium citrate which IS a chelator.

When you make soap, you can add citric acid because the alkali (NaOH) takes care of this reaction. People seem to be making the assumption that it's citric acid that's the chelator because we can get away with adding citric acid when making soap rather than sourcing and using sodium citrate. But this assumption doesn't necessarily hold trueoutside of soap making. If you add citric acid to other products, it may or may not form citrate depending on the other chemicals present.

There's not a simple black and white answer to your question. Many like to use citrate as a chelator; others prefer to use other chelators like EDTA or gluconate. It would be best to re-read the posts earlier in this thread for their opinions and use the search function to find threads that discuss the pros and cons of citrate as a chelator.

 

[penelopejane]

Is citric acid an effective chelator?

I use citric acid as it is cheap in Australia and it turns into sodium citrate in the soap process (DeeAnna knows all the scientific detail, thank you!). (You have to adjust your NaOH if you use citric acid - see DeeAnna's notes)
I find it effective. You will know because the soap doesn't go as mushy and your drains won't get clogged with soft soap.
I don't want to use EDTA because it is an avoidable chemical and I want to reduce the use of those as much as possible which is why I make soap.
Sodium gluconate is a little bit more effective than citric acid I think (in non scientific tests I did) but it is too expensive for me to use in soap in Australia.

 

[cmzaha]

I will update my earlier remark about, I now use a combination of Tetrasodium EDTA and Sodium Gluconate 50/
50 at the rate of 1% of my batch weight.

 

[Jorah]

I will update my earlier remark about, I now use a combination of Tetrasodium EDTA and Sodium Gluconate 50/
50 at the rate of 1% of my batch weight.

So this is 1% of total batch weight, including the lye water mix, not just the weight of the oils? I'm about to start using EDTA and S.G. and want to get it right!

 

[2lilboots]

I just use sodium gluconate. What I have read about Tetrasodium EDTA I prefer not to use it.