Who Wants to Make Hot Process Soap in the Crockpot?

Hot Process Soap is the easiest method for making soap and shampoo bars that are ready to use the next day. They do not need a 4 – 6 week curing time like CP soap.  However they do benefit from curing for a few days.  Curing makes the bars harder and last longer.

Why Would You Use Handmade Shampoo Bars?

Handmade Shampoo Bars are an all natural soap for your hair.  Made with oils that are good for your hair and without any additives. Who would not want that?

Easy Hot Process Soap A Tutorial

Hot Process Shampoo or Soap – A Tutorial 

I am going to show you how to make Hot Process Soap in your crockpot.  Hot Process just means you are heating the soap to cook out the lye and putting it through the saponification process in a short time.  When you are finished it will be soap.  It will only need to cool and harden.  You can get a PDF printable of these instructions and recipes here.

You can use Hot Process on any CP soap recipe. It works especially well if you are doing basic bars without any fancy swirling or colouring techniques.

Also please remember to use safety precautions when using lye as it is caustic. I will give the instructions first followed by two recipes, Rosemary Mint Shampoo Bars and Rustic Citrus Bars.

Step 1

Gather your equipment and prepare your molds. If using wood then line them with parchment or freezer paper.  You will need gloves, goggles, scales, glass measuring pitcher and an immersion blender.

Step 2

Using a scale measure the lye and water.  I always recommend measuring all the ingredients by weight including the water and the lye.  Pour the lye slowly into the water and stir until  dissolved.  Cool 15 – 20 minutes.

Melting the solid oils for hot process soap in the crockpot.

Hot process soap oils and lye just mixed together.Step 3

Measure out your solid oils and butters. Place them in the crockpot and turn on high to melt. Then measure your remaining liquid oils.  Once the solid oils have melted, turn off the crockpot and add the liquid oils.

Step 4

When the lye mixture has cooled for 20 minutes, and is between 100 to 110 degrees F, add it to the oils and fats.  Pour the lye slowly and stir the oils to blend.  When the two mixtures are combined use your immersion blender and blend alternately with stirring until the mixture reaches trace. It will look like thick  pudding. If you using any additives like oatmeal or kaolin clay add them now and blend to fully mix without lumps.

Blending and stirring alternately the hot process soap mixture to bring it to trace with a pudding-like consistency.

Hot process soap batter at trace and ready to cook in the crockpot.

Step 5

Now it is time to cook the soap.  Cover the crockpot with the lid and turn on to low. It will need to cook for about 1 hour.  I  stir it every 15 minutes. You will see it start to bubble up along the sides. After one hour it should look waxy like vaseline and be the consistency of mashed potatoes.

Hot process soap bubbling up on the sides. Hot process soap, cooked for 15 minutes.
Hot process soap, cooked for 15 minutes.
Hot Process soap, after 30 minutes of cooking.
Hot Process soap, after 30 minutes of cooking.

I use the zap test, but you can also test the ph of the soap to  to ensure doneness. Using the zap test, you will put your tongue to a small amount of the soap.  If you feel the zing like when you test a battery then the soap needs to cook more.  If there is no zing it is done and ready to place in the mold.

If you need to cook it for longer use 15 minute increments or if you are not sure if it is done, cooking for a bit longer will not ruin it.

Step 6

Once the soap is done, cool slightly and add the essential oils and colorants if using them.  I usually do not use colorants. I also added 2 tablespoons of plain Greek yogurt in the Rustic Citrus Soap at this time. It makes the soap smoother and more pourable.  Occasionally you will have to add some additional liquid to hot process soap.

Hot process soap, after 1 hour of cooking and ready to mold.

Hot process soap in a parchment paper lined mold left to cool and harden.


Step 7

Put the soap batter into the mold. I usually just scoop it in.  It will be thick and gloppy. Let it cool and harden for 24 hours. Remove from the mold and cut into bars the next day.

Want printable instructions for these recipes? Get a PDF instruction sheet and the recipes here!

Hot Process Soap Recipes To Try!

Rosemary Mint Shampoo Bars


283 grams olive oil

227 grams coconut oil

142 grams  sunflower oil

143 grams castor oil

111 grams of lye

301 grams distilled water

Essential Oils

1 Tablespoon (15 ml) peppermint

1 teaspoon (5 ml) rosemary

2 pound mold

Note: I have used 1/2 teaspoon of tea tree and rosemary instead of 1 teaspoon rosemary

Rustic Citrus Soap

270 grams palm oil

217 grams sunflower oil

193 grams olive oil

30 grams cocoa butter

56 grams castor oil

100 grams lye

224 grams distilled water

2 tablespoons kaolin clay

2 tablespoons plain Greek yogurt

1 tablespoon each lemon and bergamot essential oil

1/2 tablespoon orange essential oil

2 pound mold or individual molds

**Notes – Always run a recipe through a lye calculator and always use safety precautions when handling lye. Vinegar is good to have on hand when combining lye with the oils in case of any splashes.

If you have forgotten to get your printable PDF of the instructions and recipes, you can get it here!

3 Comments on Easy Hot Process Soap in Your Crockpot – A Tutorial

  1. Lois! Your website is great! Thank you much for all the info!! You have done WELL on your keto diet! Congrats! Colleen has made soap and is looking forward to trying your recipes!!! I love my new sewing machine…..need to really make the most of it!! Love and prayers Joyce

  2. I am now trying Hot Processed soaps and would like to use different ingredients. I only make small amounts at a time now and would like to make larger amounts for sale at our Farmers Market.

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