Many new soapmakers seem to get confused when it comes to defining saponification time and cure time when making handmade soap. The two terms are not interchangeable. Both are important to learn.
Saponification is the chemical reaction that occurs when we mix oils with a lye solution. This process usually takes about 24-48 hours to occur. During saponification the sodium hydroxide and oils are binding, doing their love dance and turning into salts of the fatty acids. Glycerin is also produced and if you superfatted (which we do), you’ll have unsaponfied oil as well.
Heat quickens saponification. If your soap goes through gel phase or if you force gel phase by adding heat, your soap finishes saponification faster.
Soap that has a high water amount, soap that is high in olive oil and other slow-saponifying oils and soap that is made with cooler temperatures might take longer to saponify.
You know that it is safe to use if you zap test it and it no longer zaps you.
The Zap Test for Soap
The zap test is when you stick a bar of soap to your tongue. If it zaps you like a 9-volt battery, your soap is still not saponfied. If it doesn’t, it is probably done with the process.
Again, saponification takes about 24-48 hours. If you have a zappy soap after 72 hours, let it set a week and retest. Occasionally, you might get a soap that takes longer to saponify. You probably didn’t stir in the right direction (always stir counter-clockwise).
Just kidding. Ignore that last line.
Can You Test Soap with pH Testing Strips?
Yes, but I don’t. I just don’t find them accurate. And they are a pain. You have to dissolve some soap either by dropping water on the bar or dissolving soap in a bit of warm water. And since the soap is then diluted, I don’t think it is that accurate.
I know that many soap makers use test strips and that is fine. I personally don’t recommend them and I don’t use them myself. If you’re interested, purchase some. They aren’t that expensive.
I stick to licking soap. Although, these days I don’t test at all. I can tell when a soap comes out good or when there might be issues. If I think there might be issues due to too much caustic (crumbly soap) I might check it several days after making it.
You don’t have to zap test every batch of soap. I use it to troubleshoot.
After saponification your soap is safe to use. You can technically use a bar of soap 24-48 hours after making it. But should you?
This is where the cure time comes in.
Curing Your Handcrafted Soap
The cure time is all about water evaporation. During the cure time water dissolves from your soap creating a harder and longer-lasting bar in your shower. Curing = drying.
If you were to step into your shower with a brand new bar of soap it would dissolve pretty quickly. It is very important not to sell fresh soap. Customers might get frustrated with a soap that dissolves quickly.
The typical cure time is 4-6 weeks. Soaps high in olive oil will take closer to six weeks to cure.
This is a good starting point, but it is flexible.
If you water discount, you won’t need the full cure time. Sometimes if I need a soap fast, I’ll discount the water quite a bit, using 1.5 – 2 times the lye amount.
How Do You Know When Your Soap is Done Curing?
There isn’t really a hard and fast rule and that is why most soap makers advocate for a minimum cure of 4 weeks.
One thing you can do is try weighing a bar of soap right after you make it. Weigh it daily. When it stops losing weight, it is probably done curing.
I feel like soap becomes milder after it has cured. I read somewhere that 95% of saponification takes place in the first 48 hours but the other 5% takes place during the cure time.
So I personally cure soap with a water discount at least 3 weeks before I use it. I feel like it gets milder.
If you are a new soap maker, make it a point to cure soap at least 4 weeks. The more you make and the more experienced you become, you can modify the cure time for your recipe and process.