Okay, here’s a little something that might interest the more seasoned soapers out there. I’m not sure if it’s something you already know, but here are my experiences anyway.
I’ve come to the conclusion that the temperature of the water with which you make your lye (sodium hydroxide, or NaOH) solution influences the outcome of whether or not your soap ends up with lots of ash on the surface.
My observations: ice water leads up to higherÂ occurrenceÂ of soaper’s ash, while room temperature water leads to much less ash, if at all.
You see, when you add NaOH to water, the reaction is exothermic, meaning it produces heat. In fact, it gets REALLY hot, hitting close to 90C. It takes some time for me to cool it down in a water bath to get it to the correct soapmaking temperature, which is between 34C to 42C.
So there were a couple of occasions where I decided to ‘cheat’ by adding ice cubes directly to my lye-making water so the solution, thinking that I could cut down my waiting time for the lye to cool.
Well, cool faster it did, and my soaps turns out fine. But I noticed that for these batches, a fine layer of ash completely covered my soap. At first I put it down to just air getting into the mold while it was covered with cloth. Then I decided to check if it was the temperature of the water to which I added my NaOH by making two separate batches of soap where the only difference was the temperature of my water for the lye solution.
One batch had water that was at room temperature, about 24C. The other batch had ice water which brought its temperature down to 11C. I made my soap as normal then loosely covered the raw soap with clean dishcloths.
Result: the batch with room temperature water had only a minimal amount of ash resting on the crests of the soap swirls. The batch with the ice water had a fine, even layer of ash that completely covered the soap, even in the valleys of the soap swirls. It looked like powdery snow actually.
Now you know what to do to achieve the desired effect for your soap. 🙂
(Alas, I forgot to take photos. DOH! #-o )