I get asked all the time about why soap needs to cure, so let’s go over that!
First, the curing rack. A curing rack is just any type of shelf that you set your soaps on so they can cure. Some soapers use wire shelves, some use bakery trays, really it can be anything. The soaps need air though to cure, so they can’t cure properly in a closed off container.
I currently use these bakery racks. But when I have more soaps I have that need to cure, I use other types of shelves, even wood crates sometimes.
I also prefer to use the trays with the little perforated holes in the bottoms of them, like this:
When I use trays that don’t have the holes on the bottom, I have to turn the soaps every couple of weeks to make sure that every side of the soap is curing properly. When I use these trays, there’s no need to turn them.
Now let’s talk about WHY I have to cure them.
These soaps are all made using the Cold Process method. (I’ll go over different methods in another post later). All cold process soaps must cure for a minimum of 4-6 weeks. However, depending on the oils used in your soaps, some soaps could take a lot longer to cure. For example, Castile soaps are soaps made of 100% olive oil and take a year to cure. No, that’s not a typo. They take a year to cure. Some soapers use them after 6 months, but most cure for 1 year.
And the reason castile soaps take a year to cure is the same reason that my soaps take 4-6 weeks to cure: so the bar will harden and the water will evaporate from the soap. The only difference is the ingredients. My soaps contain olive oil, but they also contain other oils. Castile soaps are 100% olive oil, and that particular oil takes a very long time to harden and cure.
So “curing” soaps is just allowing the water to evaporate from them, which hardens your bars of soap.
If I was to make a soap today, and try to use it next week, while it would be perfectly safe to use, the bar would feel really soft, soggy and probably turn mushy while I was using it. The longer the bars cure, the harder the bars will be, and the longer the soaps will last. Now, the only downside to curing a soap for an extended period of time – is that they will lose some of the scent if they were scented. 4-6 weeks cure time is perfect for most cold process soaps. They are good and hard and will last a long time, and will also still smell good. (Although some fragrances just do not stick in CP soap, so by the time they cure they have already lost their scent)
If you’re wondering how to know when your soap is fully cured.. there is a way to know. If I made a soap today and weighed it, let’s say it weighs 7 oz. I put it on my curing rack and check it in a week. You know what will happen? It will weigh less than 7 oz. It might weigh 6.9 oz. As the water evaporates from the soaps, the soaps lose the water weight, and will weigh less every day. So if I checked my soap every week, the weight of those bars would decrease little by little. You know when your soap is fully cured when you can go a few weeks and there is no change in the soap’s weight. That means all the water is fully evaporated from the soap and the soap is fully cured.
You also can’t over cure a soap. I have soaps in my cabinets that I made 5 years ago and I still use them today and they are great soaps. Some of them even do have scent to them still. But some of them have lost their scent. And I can tell you these bars last forever! I have 2 bars in my shower that have been in there for over 2 months and I still have half of them left.
And always remember to never leave your bars of soap sitting in water. This will make your bars soft and mushy and you will not get as much use out of them. So always pat your bars dry and keep them dry in between uses.
I hope this answered your questions about curing soaps! Thanks for the question, Vicky!
Keep the questions coming!