This post will explain the main points about making homemade soap, but there are so many details that I cannot cover them in one post. Instead I will provide some links to some other resources so you can look up the details. There are many types of soap that you can make, including laundry soap, shampoo, bar soap, etc., and each of these requires different specifics but the main ingredients and methods are always the same.You probably should not expect to save money making soap, although it is entirely possible to make soap with no cost at all using things you might throw out otherwise. The main benefits you can expect from making your own soap are the fact that you can customize it with whatever look and scent you want, and you can avoid potentially dangerous or undesirable ingredients.
All soap is made from the same (up to) four ingredients: fat or oil, a caustic "lye" solution, fragrance (optional), and color (also optional). Fat or oil and lye are the main ingredients, and are absolutely necessary.
1. The fat or oil can be either an animal or vegetable type, but mineral oil does not work. Whatever you use should be cleaned unless it was purchased fresh. However, even fat that has been rendered off a roast can be easily cleaned by simply simmering it in water and then chilling it. This can be repeated if necessary, especially if the fat was rancid.
2. Powdered lye is available commercially, although it is becoming more difficult to find. This is because it is also unfortunately an ingredient in the making of many street drugs (which is something I will NOT be covering in this or any other blog). Despite this, it can be found if you want the commercial stuff. There is a definite benefit to using powdered lye, in that you can follow an exact recipe to get the exact result you want. This is hard to do with a homemade lye solution (which I will cover in my next post).
It should be stated that it can be very dangerous to prepare a lye solution from powdered lye. When lye is added to water (it should never be done the other way) it reacts vigorously, giving off a lot of heat in the process. In fact the water can come very close to the boiling point depending on the ratio you end up using. Also, lye gives off some nasty fumes, so it is always best to mix this outdoors if at all possible. If you can't, then at least do this on the stove with the overhead exhaust fan going.
And since lye is very caustic it will burn your skin if it makes contact before it is diluted, so wear long sleeves and rubber gloves at the very least. I prefer to use safety goggles as well, a throwback to my university days in the chem lab.
3. While the lye solution is cooling down you can prepare the fat or oil, if needed. All you need to do is make sure it is in liquid form, so if you are using oil then you really don't need to do anything. Fat, however, needs to be melted, which you can do on the stove.
The lye solution should be cooler than the oil or fat under normal circumstances before you start mixing them, but each recipe is a little different. Once the temperature difference is correct you can mix them together carefully.
4. Now you need to stir the mixture, either by hand or using an immersion blender (also known as a "stick blender"). You need to stir until you reach a condition called "trace." This can take as much as an hour by hand, or mere minutes if using a stick blender.
5. Trace is a tough thing to watch for until you get some experience at it. Basically it means that when you let a stream of soap mixture run off a spoon back into the pot it sits briefly on the surface in a line before being absorbed back into the mixture. If you move the spoon fast enough you can "trace" patterns on the surface that will remain visible for a short amount of time.
6. Once you reach trace you can add any colors or fragrances, but you should do so quickly before the soap begins to set. Many a batch of soap has ended up as powdered soap because it set up right in the pot before it could be poured into a mould.
7. There are many things that can be used as moulds for soap, but you should have it lined so you can remove the block of soap easily. Wax paper makes a good liner for this purpose. Make sure to leave the mould uncovered for the first while as it cools down. You will notice it begin to gel before it hardens; this is perfectly normal. After you no longer feel any heat coming off the soap you can cover it up. The soap will get harder as it ages, but you should wait at least 24 hours before cutting the block into bars.
Soap making is a fun hobby, and once you get the bug you will rarely ever go back to store-bought. Also, homemade soap makes a great gift -- once you can make it look good!
Again, I have only scratched the surface, but my intent was to simply give you the basics so you can decide if it is something you might want to try. If you really want expert instruction, including some excellent videos, you need to look at the Visual Cold Process Guide. Not only does it show you the steps, it also shows you the mistakes to watch out for and how to avoid them. They also focus a little on the profit-making potential, but you can ignore that if you aren't looking to make money at it.