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How to Make Quick-Cure Hot-Process Soap

The simple soaps made by Dolores are popular with friends and coworkers. She has sold her soaps at a local boutique.

Home made soap

Home made soap

Homemade Soap: You Don't Have to Wait for a Month for This Soap to Cure

Homemade soap usually needs to cure for a month before you can use it—longer if you want a nice hard bar of soap that will last. But there is a method called hot-process soap making that speeds up the time it takes the soap to cure.

Heating the soap cures it quickly, making it safe to use in only 3 days to a week or two. Heating the soap will create harder, more long-lasting bars.

Use a large enamel or stainless steel roasting pan for the final heating. The large size of the roasting pan prevents a build up of too much heat. A roaster with a vent is good but not necessary. A lid is a must.

Use your regular soap recipe and method to make the soap. Homemade soap cannot be a slap-dash creation. The fat to lye proportions must be calculated according to a formula for optimum results. For a recipe, detailed instructions, and safety precautions, see How to Make Soap at Home.

Hot-process soap is sometimes a bit marbled, and quite pretty in its own way. If it looks crumbly or dry, it has been heated too much and you need to remill and add more water and oils. (Remilling instructions are at the bottom of the page.)

One problem with making quick-cure, hot-process soap is that the heat of the soap can destroy the scent of the essential oils you add for aroma. You may have to add a bit more of the oils than you would in a regular batch of soap in order to maintain a strong enough scent.

Soap mixture at trace - it looks like pudding

Soap mixture at trace - it looks like pudding

How to Make Soap - A Quick Review

  • Assemble all ingredients and materials
  • Cover and protect counter tops and self (apron, goggles or glasses, gloves)
  • Measure and combine water and lye. Always pour the lye into the water and never the reverse which can cause a dangerous reaction.
  • Ventilate the area when you combine the water and lye as it creates dangerous fumes.
  • Preheat oven 180 - 200 degrees Fahrenheit.
  • Line bottom of oven with aluminum foil in case of spills
  • Measure solid fats, melt on low heat in deep enamel or stainless steel pot.
  • Measure and add liquid fats
  • Both fats and lye solution need to be the same temperature (about 110 degrees F) before mixing
  • Slowly pour lye solution into the fats and stir
  • Mix with hand blender until trace (it becomes the consistency of pudding)
  • Add colorants. Do not add essential oils until later (heat destroys the aroma)
Home made soap in enamel roasting pan

Home made soap in enamel roasting pan

Hot process soap: You can see the shiny glicerine

Hot process soap: You can see the shiny glicerine

Hot Process Soap Making

For this batch, I used a bit less than a tablespoon of powdered Cat's Claw Bark which has healing properties. I added some cinnamon as well. You can see that before cooking, the soap was a lovely light brown color. Some colorants darken with cooking and drying and that is what happened with this batch as you can see from the final product. How you use colorants can tricky. That's where your own creative adaptations come into play.

  • Pour soap mixture into roasting pan
  • Place lid on roasting pan and place in preheated oven
  • Check after 20 minutes
  • Remove lid, tilting away from you for safety
  • Stir and replace in oven
  • After 30 - 40 minutes in the oven, the soap will look shiny and translucent with little pools of glycerin on top
  • Stir gently, scraping bottom and sides of pan to insure even cooking
  • As soap cooks, it will curl toward the center from the edges of the roaster
  • Soap will come to resemble applesauce
  • While soap is cooking, grease your mold with olive oil in preparation to receive soap mixture
  • I add a splash of water and a splash of olive oil so that the soap does not dry out. Stir in quickly and return to roaster so that it does not lose too much heat.
  • After an hour, when the soap mixture begins to look like mashed potatoes, you can remove it from the oven
  • Stir it again and add essential oils. Remember that heat can destroy the aroma so you may want to make the soap smell a bit stronger than desired in the end product.
Add oils - the same soap as above darkened with  the cooking

Add oils - the same soap as above darkened with the cooking

Homemade Soap - Curing the Soap Quickly

  • Scoop soap mixture into prepared mold. Prepare the mold by greasing the bottom and sides with olive oil.
  • Drop the filled mold onto table and run a knife through it to remove air pockets
  • Cover with plastic wrap
  • Cover with towels
  • Allow to cool for 6 - 24 hours
  • Cut into bars. Wetting the knife with hot water makes cutting easier.
  • Cure for 3 - 4 days. I often wait a week so that it hardens off
  • Trim off the edges. The sliced soap looks nicer
  • Use the trimmings to make balls of soap or remill
  • Set out the soap to cure on a rack (not aluminum). Let air curculate.
Slice the soap

Slice the soap

Test the Soap

Wearing gloves, wash hands with the cooled soap. Does it act like soap? Does it produce lather?

Tongue test - touch your tongue to the soap. If it buzzes, wait a week more.

PH strips can indicated how alkaline the soap is. Make a slurry of soap and warm water until the soap is dissolved and follow the instructions on the box. Cured soap should show 8 - 10 on the pH scale.

If it doesn't seem right after a week, remill the soap, adding a bit more water and fats.

To Remill Soap

If you have extra shavings you can remill it. Of course, if the soap has already cured, you will only have to wait for the newly remilled soap to harden.

  • Cut or shred soap into very tiny pieces.
  • Place in glass or Pyrex container with a bit of hot water.
  • Mix well.
  • Heat a few seconds in microwave.
  • Stir. When mixture is wet and gloppy, put into greased mold.
  • Slice when set.
Homemade soap - the same recipe can produce many different bars of soap

Homemade soap - the same recipe can produce many different bars of soap

Questions & Answers

Question: Do you always have to use lye to make soap?

Answer: Soap is the result of a chemical reaction called saponification. This is a reaction between lye and fats. The resulting product is soap. Lye is also called caustic soda, and sodium hydroxide (NaOH). After the chemical reaction, there is no lye. It is soap. Cleaning products that are made without fats and sodium hydroxide are not actually soap. Some are detergents. Certain popular soaps contain ingredients called "Sodium tallowate" which is beef fat that has been saponified.

In other words, you always have to use lye to make soap.

Comments

Dolores Monet (author) from East Coast, United States on May 11, 2010:

prowork - the lye does not hurt your skin because you are very careful when you make the soap. In the soap - well, after all the elements are mixed correctly, and the mixture reaches the trace stage, then cools, and sits to 'cure,' the lye is just part of the whole. It's a chemical reaction. All soap contains lye. The stuff you see in stores can be 'cleansing bars,' or whatever, but they are not soap. Find yourself some home made soap in a shop and read the ingredients, you will find sodium hydroxide, which is lye.

The recipe above costs about $13.00 for the basic ingredients, then add the cost of essential oil which can vary. For instance, some oils cost $24.00 an ounce while others costs maybe $7.00 an ounce. But that makes a batch that fills a 12 x 8 x 4 inch container so that's quite a lot.

Pro, you seem real interested, you should try it, it's just great. If you like that sort of thing.

prowork from Marietta , Ohio USA on May 11, 2010:

I don't understand how the lye dose not hurt your skin ? How much dose it cost to make homemade soap ? I loved reading this and am very interested in trying it.