Hot Process Soapmaking
After using cold process for a while, you might get itchy to try something new and different -- I did. Hot process soapmaking is a method of making soap by which you introduce heat to speed the reaction. Saponification is an exothermic reaction, meaning that it produces heat. As it happens, applying more heat makes saponification go faster -- that's why, in cold process, the gel stage is so important -- the "gel" portion is the soap which has heated up significantly due to exothermia. As a result of speeding saponification by using a hot process, the 6-8 week curing process of cold process is shortened dramatically, down to anywhere between 1 day and 3 weeks depending on your method.
There are many ways to hot process soap. The original -- think pilgrims and cast-iron pots over bonfires -- is direct-heat hot process, or DHHP for short; the direct heat method means that, after you mix your ingredients to trace, you put the pot on the stove, light the fire, and stir like crazy until it's done! Good for you adventurous types. This method typically reduces the most water of all HP methods, and the soap will be ready to use as soon as it is cold and cut into bars.
Find more information on direct-heat hot process at Melanie's excellent pictoral direct-heat HP instructions page -- from which I learned to HP!
My personal favorite hot process method is the closed-system double-boiler hot process, or CSDBHP for short. In CSDBHP, you set up a double-boiler system, where your traced soap mix goes in the smaller pot, and the outer pot is full of boiling water. The double-boiler prevents your soap from scorching, which in turns prevents you from having to stir for two hours. I find CSDBHP soap easiest to work with, because there is still enough water remaining in the soap after the cook that it molds easily, but has to cure only a week or two.
Find more information on this method at Diane Buckley's Enclosed DBHP page.
Also, this is the handout I use for my CSDBHP demonstrations.
Closed-system double boiler hot process is, as the name suggests, a variant of double-boiler HP, shortened to DBHP.
A newer method which has gained popularity in the past couple of years is crock pot hot process, which is similar to CSDBHP where you cook the soap in the closed container. Batch size is limited by the size of your crock pot, which is necessary to keep in mind when creating your recipe.
Another high-volume method is oven hot process, wherein you put your traced soap in the oven, at a low temperature. The ambient heat inside the oven heats the soap mixture indirectly, which prevents scorching.
Diane Buckley provides a great oven method web resource.
Finally, there are the "wrapped" methods of hot processing. This is a no- cook hot process. How can there be such a thing? Follow this link and find out!