If you’ve ever used cold process soap or if you’ve just been eyeing it on store shelves, you’ve probably noticed some bars have this uneven white, ashy powder or film usually on top, which gives them a frosty look, as if they’re getting ready for Christmas or something. To some bars it may lend a sort of a vintage appearance, which some people really enjoy.
Ever wondered what that white thing is all about? Here it is: it’s called soda ash.
What is soda ash?
Soda ash results during the curing process as a reaction between unsaponified lye and the carbon dioxide in the air. It occurs especially if the soap maker mixes the oils with the lye at lower temperatures and pours the soap at a thinner trace (see our previous articles for explanations of these terms).
It is easily removed once the soap is in use, it is totally harmless and it doesn’t affect the bars, which are safe to use. Nevertheless, it can be frustrating if it hides the soap design or if people don’t know what it is. The soap maker knows there are ways to prevent it from forming (which don’t work every time) and ways to remove it once it has formed.
But again, it’s totally harmless and can actually make some soaps look cool. Like our soap right here, which was the soap we made for Christmas last year. Soda ash can be the perfect decoration for a winter soap, don’t you think?