There are a few different methods of making soap. Cold processed, hot processed and melt and pour.
Cold processed is where you mix your oils with your lye water and let the soap set in the mould overnight/for a couple of days. You then need to let your soaps cure for a few weeks before you can use them.
Hot processed soap is when you cook your soap in a crockpot or put into an oven to speed up the saponification process. (Saponification is the chemical reaction that occurs between your fats/oils and the lye solution to create the soap. Once it is complete, there is no lye remaining in the soap). The soap can be used a lot sooner and doesn't really need to cure.
Melt and pour is different in that you aren't actually making soap through saponification, rather melting down a base soap made of glycerin or white coconut oil and adding colours/fragrances and shaping them in different moulds.
|Safety first. Safety is sexy.|
Safety: Before you do anything, please make sure you are wearing appropriate safety gear. Gloves, long sleeves, safety goggles and/or a face mask. Using hot oils and caustic soda can be dangerous and has the potential to cause nasty burns if it isn't handled safely.
So, the first thing you need to do is weigh out all your ingredients (including your water). Depending on what fats and oils you are using, you should run your ingredients through a soap calculator. You can find quite a few of them around the net. Making soap is a science, and you need to be quite precise with your measurements.
Next, melt your oils on a slow heat. (Don't use an aluminium pot or utensils, as it will react with the lye)
While they are melting, add your lye (caustic soda) TO your water in a separate container. Never add your water to your lye, it can cause a volcano-type reaction. So I've been told. Probs best to not try it.
The water/lye solution will heat up very quickly, and be quite whiffy, so make sure you're wearing a mask, or are in a well-ventilated space. This is probably not the sort of project you want little Billy helping with.
Using a candy thermometer, wait for the temperature of both the oils and the lye solution to cool down to about 50C. They need to be roughly the same temp.
Now you can add your lye solution to your oils. It will start to turn opaque. At this point, using a handheld stick blender is probably the easiest way to mix the soap.
It will start to thicken and you want to bring the mixture to 'trace'. This is when the mixture has reached a pudding-type consistency, and if you pull your stick blender out, you will see in the mixture where it was, it's left a 'trace' in the soap. Make sense? I haven't had my coffee yet.
At this point you can add your fragrance or any colour you want to use. I used lemon myrtle oil. Again, you want to run these measurements through a soap calculator so you know how much
fragrance oil to use.
Mix again, then you can pour into your moulds. You can use pretty much anything as a mould. I used silicone moulds but you could use a lined wooden soap mould, or a tupperware container. You could probably use a lined cardboard box in a pinch.
I covered my moulds with a piece of cardboard, then wrapped them in a couple of towels to insulate them, and let them cure for 24 hours.
Problem. The soap was REALLY soft. I'm not sure if I had the mixtures too hot still, or if the fragrance oil affected the mixture. Castile-type soaps (olive oil soap) is the softest soap you can make, so I'm not sure if that was normal or not. It was too soft to unmould after 24 hours, so I stuck it in the freezer for an hour to harden them up so I could unmould them. I placed the soaps into drying trays (just little office trays I picked up from the Reject Shop) and have been turning them once a day. They were harder on day 2, but still quite soft. These soaps will need to cure for about 6 weeks.
So that's it! It's really not that complicated, and I think most people put off trying soap making because of the lye. Just jump in and have a go if you're considering it! We've got enough soap to last us a few months now.