Wednesday, April 3, 2013

Chemical of the day: EDTA in soapmaking

One of the problems soapmakers face is the bound-to-happen dreaded orange spots (DOS) that appear on the soaps usually 2-4 days after molding. These spots are caused by one of the following:

a.) Too much superfatting
b.) Rancid Oil used
c.) Short shelf life of oil
d.) "Soft" oils (olive, canola, sunflower, e.g.)
e.) High temperature curing

Another problem soapmakers face is the production of soap scum which unpleasantly creates mess in the bathroom and even in the soapmaker's workplace. 

Soap scum and DOS can be prevented by using EDTA.
EDTA is white and is in powder form. 

How to use:
1. Dissolve EDTA in distilled water with Sodium Chloride (Salt).
2. Add during light trace.

1. Dissolve EDTA in lye water.

1. Dissolve EDTA in Distilled water before adding lye.

Always remember that you can't state your soap as "Organic" once this chemical is placed. In order to avoid using EDTA, always check your measurements and check the shelf life of your oils. To prevent soap scum without using this chemical, you can use hardening agents that are natural like Sodium Chloride (Salt) or Cera Alba (Beeswax). These natural ingredients can hold the bar together stronger and it can help reduce soap scum.


  1. How do I determine how much EDTA to use? I've noticed since making my own soap that the scum is worse in the shower--I've now cut down on supperfatting as a result. I use EDTA in my shampoo recipe (not a soap recipe--surfactants) and I'd like to try it in my bar soap recipes but haven't found a place that tells me how much to put in!

  2. How do I determine the amount of NaCl required ?

  3. Whats the percentage of EDTA should be added n tell me e.g 100g EDTA can be disolved in how much lye??