Hot process soap making is pretty much like cold process soap making and you can even use the same recipes for both. The only difference is the addition of heat needed to cook the soap during the hot process. This, as a result, will evaporate more water and give you a harder bar of soap much faster than with the cold process soap making.
Chose your location and set up all your equipment before you start so you won’t have to look for anything in the middle of the process.
I usually cover my work surface with a vinyl table cloth because it is easy to clean and you can reuse it many times. Also, oil doesn’t leak through so you won’t have to clean up a mess afterward.
For hot process soap making, in addition to the usual equipment, you will need a crock pot so be sure you have that ready before you start. If this too hard I would suggest just buying a natural chemical free soap 🙂
Measuring your ingredients
Measuring your ingredients is a crucial part whenever you want to make homemade soap. In fact, inaccurate measurements can result in soap with too much lye (which is caustic) or soap with too much oil. Here are some ingredients:
First, I advise you to take a good scale and start measuring the oils and essential oils you want to work with. Remember, every measurement have to be done by weight and not by volume. Oil and water don’t have the same mass.
Second, prepare your lye solution. For this I use 1/3 lye for 3/3 water. Once everything is measured, pour the lye in water and be careful of the fumes it gives up. As I don’t wear a mask, I leave the room for few minutes and wait for the fumes to disburse.
Remember; when lye dissolves in water, it heats up to 200°F so I would recommend using a Pyrex container as it will easily withstand this kind of temperature.
Also, DO NOT pour water on lye, this will have a geyser effect which would be very funny for a five years old kid, but not so much for anyone who care about his work place.
Finally, put the solid oil in your crock pot and set it on low. Once the solid oil has completely dissolved, add the liquid oils.
Mixing lye and the oils together
Hot process and cold process soap making start to differ during this part. With hot process soap making, you don’t need to wait for the oils to cool down, which is a time saver!!!
Get your whisk or stick blender and start pouring a thin stream of lye solution while stirring the mixture. Keep stirring steadily, not to strong (you don’t want splashes everywhere) but not to slow either until the mixture turns creamy and start to thicken. Don’t stop stirring until your mixture reaches a thick trace.
Starting to cook the soap
When your mixture reaches a full, thick trace, it is time to cook it to force the gel out. Put the lid on the cock pot, set it on low and let it for a while. You will see that your soap is going to start bubbling around the edge of the pot so keep an eye on it and stir it down if it begins to bubble over.
The soap will clear out and start to look like Vaseline. When the soap reaches a waxy effect, it is done.
Once your soap has this waxy effect, it is time to add any additive you want your soap to be made with. Remember though that you need your soap to cool down a bit before adding any essential oils, otherwise, if the temperature is too hot, they will ignite and vaporize.
This part is the tricky one as you need to work quickly. Everything has to be done before the soap has cooled too much to be poured in the molds.
You will have to scoop out your soap in the molds as, at this point, it is too thick to be poured. Make sure not to leave any air pockets if you want to have a nice result.
Unmolding, cutting and curing
Once your soap has cooled down to room temperature, it’s time to unmold it. When it is done, cut your soap right away into bars.
After all of this, your soap needs to cure. Opinions differ on how long your soap needs to cure, but personally I like to let it cure for 3 to 4 weeks.
Now you’re done, you’ve just finished making homemade soap using the hot process technique.