Have you ever been curious what happens as soap cures?
The first thing that is going on in that soap batch is the saponification reaction. The oil and the lye are combining to form new substances, soap and glycerin. Saponification is an exothermic reaction which means it gives off heat. The soap may “gel” and turn transparent as the reaction continues to takes place. If the soap has gone through this gel phase, it will slowly “un-gel” and become opaque again.
After 24-48 hours the soap in the mold has usually cooled down and can be cut into bars. The bars are put on a rack to cure. The saponification reaction may not be complete, depending on the oils used. Olive oil tends to saponify slowly and coconut and palm oils more quickly. The soap is very soft at this point, there is a lot of excess water in it. The water needs to evaporate from the bar so it hardens up. A soft bar of soap will dissolve very quickly. A soap maker wants to make a hard bar of soap. The harder the bar, the longer it will last. Since water is evaporating from the bar, the weight of the bar decreases too. Personally, my bars lose up to 0.5 ounces during this time.
The curing process takes 4-6 weeks. I know it’s a long time when you’re waiting for your favorite soap to come back in stock, but good things are worth waiting for.
Yours in Gratitude,