# EDTA & bad math

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#### BlackDog

##### Well-Known Member
So I'm doing some calculations for a batch of soap today, which will be the second batch to which I add a 39% solution of EDTA for chelation. It's a similarly sized recipe to the one I previously added EDTA to, and I noticed that the amount of solution was quite different than the first.

I have been using Irish Lass' two-part equation to calculate, but after recalculating the first and second recipes it turns out that I badly botched the first one. Apparently as a musician who can only reliably count to 4, I accidentally doubled my oil weight so there's way too much EDTA in the first batch.

My question is, is this super-chelated batch now trash? Will it cause ill effects in the soap? It's now two weeks old and I haven't done any testing yet.

#### DeeAnna

##### Well-Known Member
Am I following you correctly -- your first batch has 1% EDTA rather than 0.5%? If so, I suspect you won't notice any large difference between the two batches. I think it will be fine if you just go ahead and use it as usual.

Here's my rationale -- Sources I've read (lotioncrafter and similar places, Scientific Soapmaking, commercial soap making manuals, manufacturer's literature from Dow, etc.) cite a wide range of dosages for EDTA. Just a tiny dose (0.1% ppo) is all that is needed for DOS control, but you can theoretically use up to a few percent for soap scum control. I've made a couple of laundry soap batches with higher EDTA, but I didn't see any amazing or unusual things happen, either good or bad.

So my thought is that higher dosages are not necessary -- I'm all for using about 0.5% max EDTA. That said, the soap won't become glowing radioactive waste or explode if you use more. (Just joking!)

#### BlackDog

##### Well-Known Member
Yes DeeAnna you are correct. I meant to put in .5% but with the miscalculation it ended up being closer to .8% or so (estimate without my notebook in front of me).

I had read that .5% was a max figure and the soap *looked* ok so far (it's two weeks old) but I haven't done any testing on it and just wasn't sure if it would be ok to use lol.

#### DeeAnna

##### Well-Known Member
I really do think the soap will be fine. Don't worry...!