There are several different ways to make handmade soaps. Let's take a look at them.
Cold Process Soap
This is the kind of soap I make, and the kind that we examined the Basic Soap Chemistry series. It is called the cold process method because no heat is added during the saponification process. The process itself generates heat, but no extra heat is added to the reaction.
These types of soap are opaque, with a heavy feel and creamy look to them. Soap makers can go crazy making colors, swirls, and designs with this type of soap.
Hot Process Soap
This kind of soap is called the hot process because heat is added during the saponification reaction. Because of this, the reaction takes much less time than cold process, and many people find that the soap is ready to use much sooner. The additional heat helps to evaporate some of the moisture from the soap.
These types of soap are also opaque, and tend to have a more "rustic" look than cold process. This is due to the reaction occurring more quickly, and the resulting soap batter is less fluid when put into the mold to harden.
Glycerin Soap (Melt and Pour Soap)
Technically, all soaps are "glycerin soaps," as the glycerin is not removed from the finished soaps. However, here I am specifically referring to soaps that created from pre-made bases. They are called Melt and Pour soaps because the bases are purchased, melted, and then poured into molds. There is no chemical reaction here, as the base has already undergone the saponification process.
These types of soaps can have many different looks. Some may be opaque, but others may be transparent or translucent. Because these soap bases are pre-made, many times more intricate designs can be achieved with them than either hot or cold process.