Krista, I use tetrasodium edta in my soaps all the time (we have hard water). I make a masterbatch solution out of the powdered edta with enough warm distilled water to dissolve it/turn it into a 39% solution (39% is the perfect % to keep the edta in solution without precipitating out). I store it in a 12-oz plastic bottle with a flip-top for easy dispensing, and I add as much of the solution as I need to my oils either before or after adding the lye solution (either way works fine).

The rate at which I use the edta is @ .5% of my entire/total batch weight, but that .5% figure is based on the amount of EDTA I need in

__solid form__, which means that I have to do a little bit of math to figure out the amount of 39% solution to use that will ensure that my batch will contain a total of .5% of actual EDTA.

Yep- extra math. I can hear the groans already! LOL No worries, though.

I promise you, the math is very simple (if I can do it, anyone can!). Just follow this simple formula:

1) Total up the

*entire* weight of your batch in

__grams__ (i.e. oils, fats, water, fragrance, additives, etc..)

2) The sum of the total weight of your batch multiplied by .5% equals how much of the

__powdered__ EDTA needed for your batch.

3) The amount of powdered EDTA needed multiplied by 2.56 equals how much of the 39% solution to weigh out for your batch

__in grams__.

And that's it!

For my hard water issues, .5% works fine for me, but if your water is not as hard as mine, you can certainly use less of a %. Whatever % you decide to use, sub it in place of the .5% in the above equation in order to get the correct amount of solution to use for your batch/

I hope that made sense. If not, please let me know.....or else maybe someone with a different/easier way of explaining it can chime in.

RE: EDTA in lotions. EDTA is not a preservative and cannot be used tin place of Liquid Germall Plus or any other preservative. Instead of being able to actively kill off bugs like a normal preservative does, EDTA is what is known as a 'preservative booster', whose effects are limited to only being able to starve bacteria of their food by causing a disruption of their digestive system. Basically, it weakens the bacteria, which enables your chosen preservative to have an even greater killing effect. I use it in my lotions at .2% (powdered form) along with phenonip. I heat it with my water phase.

IrishLass