### Help Support SoapMakingForum:

#### samirish

##### Well-Known Member
So I went and purchased some EDTA to try in my cp soap. However, Im struggling with trying to decide exactly how much to add to my batch.
My total oil weight (not including water or lye) is 4.5lbs. The total weight with the water and lye added is 6.5lbs.
How much EDTA should I add to this batch?
Thank you,
Stacey

#### IrishLass

Staff member
Moderator
Hi Stacey- when I use EDTA, I use .5% as per the total weight of my batch, i.e., oils, water, lye, colorants, FO and whatever other additives I choose to use.

If you are using the EDTA in powdered form (as opposed to the 39% solution form), the easiest way to calculate is to just multiply your total batch weight in grams by .5% in order to get the gram weight of the EDTA powder to use. Note: when adding the EDTA to your batch- powdered EDTA dissolves best in warm/hot water.

If you are using a 39% solution of the EDTA (which is the form that I use), a little more math is involved to get the correct amount to use, but it's very easy math. Just add up the total weight of your batch in grams and multiply by .5% as I mentioned above, then take the resulting sum of that and multiply it by 2.56. The resulting sum is the amount of 30% EDTA solution (in grams) to weigh out for your batch.

Example- if the total weight of your batch is 6.5 lbs/2948g and you are using the powdered form......2948 x .5% = 15g powdered EDTA (rounded up) to add to your batch.

Or, if you are using the 39% liquid form of EDTA...... 2948 x .5% = 15g........ 15g x 2.56 = 38g EDTA solution to add to your batch.

HTH!
IrishLass

#### topofmurrayhill

So I went and purchased some EDTA to try in my cp soap. However, Im struggling with trying to decide exactly how much to add to my batch.
My total oil weight (not including water or lye) is 4.5lbs. The total weight with the water and lye added is 6.5lbs.
How much EDTA should I add to this batch?
Thank you,
Stacey
It depends on what you are using it for. In cosmetics and toiletries, EDTA is typically used in the range of .05% to .5% in commercial products (by product weight), which as you can see varies by a factor of 10. The high end of the range is recommended by people on the board who are seeking improved performance of soap in hard water (more lather, less soap scum). To stabilize soap against DOS, the bottom of the range works well.

The amounts are from about 1.5 g to 15 g for your batch.

For protection against DOS, there have been actual experiments with EDTA in soap at .1% of oil weight. At that rate, it would be 2 g for your batch.

Last edited:

#### samirish

##### Well-Known Member
Thank you so much! Yes I have the powdered form and will times my batch by .5

#### cmzaha

Supporting Member
Thank you so much! Yes I have the powdered form and will times my batch by .5
You do not multiply by .5. High end is .5% which is .005

Staff member