What's That White Stuff on My Soap?
Susan Miller Cavitch, in The Soapmaker's Companion, calls it the "million dollar question." Most soapmakers, at one time or another, will find that a white, powdery film has covered their bars of soap. It's most usually on the tops or sides - those sides exposed to the air. In the soap making world, it's called "ash." Some people believe it's sodium carbonate formed by the free sodium from the sodium hydroxide (lye) and carbon dioxide in the air. Cavitch once had a chemist test some ash on her soaps...and theorizes that it's actually microcystalline powdered soap. It generally forms during the first 12-24 hours after you pour the soap, and different people have different solutions for it. I knew a soap maker that added 1-2% soy or beeswax to her soap batches and greatly reduced her ash. Cocoa butter seems to have a similar preventative effect. Covering the soap with plastic wrap after you pour it, so that no air gets to it seems to minimize it as well. The good news is...that whatever "ash" really is...is that it's harmless and washes right off of the soap.
Comments
Made my first really beautiful soap this month, rosewater hibiscus. Learned to swirl (finally). But-ash on the soap. All of the ugly soaps I’ve made in the past-no ash. First nice bars I make and I get the ash. I wish I had seen this post before the market on Saturday, I would have been able to explain it!
First thank you for this.
All the time I made my soap’s simple or with diferent herbs like Calendulla,Camomille etc.I found that white powdery covered my bars of soap. Or become verry hot after 2 hour if I covering the soap with plastic wrap or towel. I use NaOH 99% it’s ok?
thank you!