A couple of years ago when I started making homemade soap, I was scared. Soap seemed so complicated. Once I started making it, I realized it was quite simple–and even easy. I wrote a post, How to Make Soap. While that post is still useful, especially for someone who has never made soap before, it includes a lot of information, for both cold and hot process. If you’re new to soapmaking, you need that base of knowledge, but the info overload does make it difficult to use the post while actually making soap. If you’re the type who likes to set your laptop open to a tutorial as you’re working through a new project, this post is for you–whether you’re a brand new soapmaker or you’ve made soap a time or two but still need the directions at hand.
This post contains simplified directions for hot process only. If you’re new to soapmaking, please absorb the more detailed information and instructions in How to Make Soap first then come back here to set your laptop open to this post as you make your soap.
If you’re ready to get down to the business end of your stick blender, let’s go!
This is my favorite soap recipe for a soft and nourishing bar with a light lather. The recipe below makes a two-pound batch, which is a good batch size for a beginner or when trying out a recipe, though I find a four-pound batch size is easier to work with when doing the cook. To make a four-pound batch, just double the recipe. (Likewise, if you prefer a one-pound test batch, cut it in half.) Be sure your crock pot is large enough for the size batch you’re making! Choose your own additives, fragrance, and coloring to make a unique soap.
If you want to use a different recipe, go ahead. You can use any soap recipe to make hot process soap. I’m providing this one here because I like it. You can find many recipes with exotic (and sometimes expensive and special order) fats and oils. I’m a farmer. I prefer easy-to-find, inexpensive, grocery store fats/oils that create a soft and cleansing bar.
Crisco — 9.6 ounces or 272.155 grams
olive oil OR olive oil pomace — 9.6 ounces or 272.155 grams
lard — 6.4 ounces or 181.437 grams
coconut oil (76-degree melt point) — 6.4 ounces or 181.437 grams
distilled water OR milk* — 12.16 ounces or 344.73 grams
lye — 4.463 ounces or 126.524 grams
*You can exchange milk with water, but the milk must be icy-slushy before being mixed with the lye. Milk will also darken soap, making it a natural brownish color, which is nice, but just keep it in mind–plan on going with the natural coloring if you’re going to make a milk soap. Read more about making soap with milk here.
CAUTION: Wear goggles and gloves any time you’re dealing with lye and while handling the soap until it tests non-caustic.
How to make Hot Process Soap:
Gather all tools, utensils, ingredients, and other supplies including your molds and prepare your work area. To make soap by the hot process method, you don’t need to take the temperature of your mixtures at any point. Just carry on the way your great-grandma did, except without the iron kettle and the open fire.
Weigh each fat/oil.
Place fats/oils in a crock pot on Low.
Heat until completely melted. Turn the crock pot off.
Put on your goggles and gloves. Weigh the lye–
–and the water (or milk).
ALWAYS ADD LYE TO WATER (or milk), not the other way around. I take the lye and water (or milk) outside to mix, releasing the fumes in the open air. Slowly pour the lye into the water (or milk). Stir with a slotted spoon and hang back so you don’t inhale the fumes. A water mixture will appear cloudy at first.
The mixture quickly clears. Take it back inside.
Slowly pour the lye mixture into the melted fats/oils.
Stir briefly with a spoon then begin mixing with a stick blender.
Use the stick blender on and off so you don’t burn up your tool. This recipe takes me about 10 minutes to trace. (May take longer if using milk.)
When your mixture traces, it will be sort of like a soft pudding where you can draw a line in the mixture and see the “trace” you left behind.
Set your crock pot to Low and put on the lid to start the cook.
The soap will gradually take on a waxy appearance. The edges will appear dryer than the middle as they push up the sides of the crock pot. Stir occasionally–this keeps the soap mixture cooking evenly. As it nears finishing, it will look like waxy mashed potatoes.
You can test it with a pH strip (usually takes several minutes to change color after dipping in the soap) or do the “zap” test with your tongue. My preferred and recommended method for testing is using a 1% phenolphthalein solution. When you think the soap is ready, take out a small dab and place on a paper plate. Put one drop of the solution on the soap. If it’s ready, it will remain clear. If it’s not finished yet, it will turn bright pink! Very easy and clear cut way to test soap.
The cook time of soap recipes will vary with the fats/oils involved. It takes about an hour for me with this recipe.
Once the soap tests clear, it’s no longer caustic and is safe to touch.
This is optional, but I prefer to transfer the mixture to a new bowl and continue to stir for a couple of minutes, letting the soap cool slightly. This helps reduce the chance of a too-hot mixture “cooking out” your fragrance. In this case, I was making a two-layer soap (different additives, fragrances, and coloring) so I divided the soap.
Mix in the additives and colorant, if using, as you stir. There’s a fine line between letting the soap cool slightly and letting it begin to harden, so don’t over-do it. Add fragrance last. Additives and fragrance should be measured and prepared before the soap is ready to come out of the pot so that you can work quickly.
Additives: Use a maximum of 1/2 cup dry additives in a two-pound batch. (More may make your soap crumbly.) If adding honey, add 2 tablespoons per two-pound batch.
Coloring: I prefer liquid soap colorant. I find dry pigments are more difficult to blend evenly. Be sure you’re using soap colorant. Use as many drops as it takes to reach your desired effect. You can also color soap naturally in a variety of organic ways, and keep in mind that some additives (such as ground cinnamon) will color your soap.
Fragrance: Use no more than 1 to 1 1/2 ounces fragrance oil or essential oil per two pounds of soap. (More may make your soap oily.)
Scoop the mixture into the mold. Making two layers here, I placed the pink on the bottom and the yellow on top.
This is a “cherry-pawpaw” soap with cherry fragrance and red soap colorant (to turn it pink) on the bottom and banana-mango (“pawpaw”) fragrance and yellow soap colorant in the yellow layer, with the addition of dried ground banana (since I have no pawpaws yet) and the liquid from several Vitamin E capsules. (Vitamin E, aside from other benefits, is a preservative.)
When making hot process soap, by the time you put it in the mold(s), it’s soap. You may line the mold (I use freezer paper) to protect the mold (for example, a wood mold) from the oils in the soap and to make the soap come out easily. Unlike when making cold process soap, you’re not lining molds of various materials to protect from the reaction of the mixture prior to saponification. Hot process soap is already saponified by the time it goes into the mold. (See Pringles can note below.)
Bang the mold down a little to settle, cover the soap (I just fold over the freezer paper I used to line the mold), and clean up your work area.
As soon as the soap is cooled and hard–about 12 hours–it’s ready to remove from the mold, cut into bars, and use. I usually set the bars on end for a day or two while they continue to set.
Hot process is real soap, real fast!
Pictured with the “cherry pawpaw” soap is an apple-oatmeal soap–both made from the same base recipe above. In the apple-oatmeal, I used no coloring. Per two-pound batch, I added 1/4 cup ground oatmeal, 1/8 cup brown sugar, 1/8 cup white sugar, plus Vitamin E, and 1 ounce apple pie fragrance oil. The oatmeal and sugars make a lightly scrubby, conditioning bar combined at the same time with the soft and nourishing base recipe.
FYI, to make round bars, I use Pringles cans. No need to line them for hot process soap–eat the Pringles (get your kids involved, they’ll find it a real hardship), clean the can out, spoon the soap in, and just tear the can off when it’s ready to cut into bars.
See all my homemade soapmaking posts here.