Hot Process Soap- How To Make Homemade Soap

There are so many items in our stores that have unnecessary packaging. Cardboard or plastic wrapping that makes it pretty on a store shelf, but does little else. Some will have BOTH, like soap. Store bought soap will often come in a carboard box, wrapped in plastic. Guess they don’t want it to spoil?

Some soaps also contain detergents that can dry out your skin. The harsh chemicals can also cause a reaction in some. Let’s not forget the scents they use, that can cause headaches or other allergic reactions in some. It’s been suggested that fragrance is the new “secondhand smoke”, with detrimental health benefits. (source) 

The solution many come up with for commercial soaps is to buy homemade soap from local health food stores. While this is great and supports local artist and crafters, it can be very expensive. To the tune of $12.99/lb for some. But when you need soap NOW, what can you do?

Learn to make your own hot process soap.

Hot process soap is simply homemade soap that is cooked either on the stove top or in a crockpot. The difference in hot process versus cold process soap is the cure/ready time. Cold process soap will saponify the lye over time, typically taking 6-12 weeks. Hot process soap will saponify the lye while it is heating, making the soap ready to be used in 60-90 minutes.

When you make your own hot process soap, you can control the ingredients you want in there. Homemade soap can be unscented, or use different herbs or essential oils to get the properties you want.

Need a soothing, calming scent? Try adding lavender to your homemade soap. Need a more manly scent? Perhaps patchouli or cedarwood essential oils are what you are looking for.

bar soap post

To Make Your Own Hot Process Bar Soap

What you need to gather (links to products are all affiliate links)

Gather your ingredients together and weigh out for accuracy.  Other items you will need:

  • crockpot
  • a measuring cup
  • stainless steel bowl
  • digital scale for accurate measurement
  • wooden spoon
  • safety equipment such as eye protection and rubber gloves for working with the sodium hydroxide.
  • white vinegar

You will also want to make sure your sink is ready with hot, soapy water and pour some plain white vinegar in there as well. I put about 2 cups of vinegar to 1 gallon hot water to neutralize the caustic lye.

homemade soap bar

Putting your homemade soap together:

  • Measure out your oils in liquid form.
  • put liquid oils, castor and olive, in the crockpot as they are measured.
  • The solid oils, coconut and cocoa butter will need to be measured solid and melted down. You’ll want to be careful to not let them get too hot on the stove. Melt the solid oils or butters until JUST barely melted.

soap steps numbered

Measure your lye and water.

I can’t stress enough how you need to be careful using this caustic.  When you mix these two ingredients together, always pour the lye into the water and not water into the lye.  The chemical reaction could cause it to volcano out of the bowl. It will get very hot very quickly and the odor is quite strong for a few moments.  I put mine in the windowsill, and open the window while it is cooling off.

homemade soap bars

Make your own dandelion infused shampoo bars by reading the post here. 

Now, you are ready to make your homemade soap:

  • Mix your solid oils with the liquid oils in your crockpot.
  • Gently, gently, gently, add the lye to the oils.  Please make sure to use the protective equipment, as splashes can and do occur! Then, stir the oils and lye water together.
  • You can stir with a spoon to get to “trace”, but I much prefer at this point to use a stick blender for 5 minutes. Trace is achieved when the mixture begins to resemble custard and falls back in waves.
  • How long to cook hot process soap is typically 60-90 minutes.
  • While it is “cooking”, prepare your molds. I use an old drawer organizer I found at the thrift store for $.50.  Line it with parchment paper and grease it with some coconut oil.
  • After an hour, your hot process soap will be “done.” It will look clear in some spots, and may have glycerine on top. Just stir that good stuff right back in.
  • At this point, if you are wanting to add essential oils for scent, add 2 teaspoons desired scent at this step.
  • Pour your soap into the mold, and let it sit overnight undisturbed in a cool area. Hot process cure time is usually 4-6 weeks, to properly harden, but can be used right away, as the cooking process soaponifies the lye.

homemade soap block

The next day, take out your homemade soap block and cut into the size pieces you want.

I got 32 bars from this batch, and it’ll last my family of 5 about 6-8 months. I store in the bathroom linen closet, and you can rotate them once in a while if you want.  They will continue to “cure” and harden as they sit, but they are ready for use right now.

soap bars

Do you make hot process soap? Will you try this method next?

Check out the video below to get further help. Please be sure to check out the very ending, where my uber OCD hubby is scraping the soap!

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27 thoughts on “Hot Process Soap- How To Make Homemade Soap”

    1. I usually find the coconut and olive oils in the baking section, the castor oil in the pharmacy by the first aid, and the sodium hydroxide is in the drain cleaner at Menard’s…usually under the brand “Roto Rooter”. But, I usually order them online because it’s much easier to get them in one location, and for the most part cheaper.

  1. Jessica Steckler

    Do you ever add any scents to your soap? If you do, does the recipe need to be altered? Also, I made my first batch this past weekend and mine is a lighter color. Did I do something wrong? Thanks!

  2. I have pinned this and will have to come back and look at it more closely. I take bar soap and make liquid soap out of it so I will need to check this out.

      1. Ok, I have a question. Would you have any suggestions as to what I would do to keep it from getting hard? Do I cook it less? I want the liquid form to make my shampoo and body wash.

        1. This particular recipe is for hard bar soap. What you could do is make this bar soap and then grate it to make liquid soap. I have a recipe for that here. You would need to use a different form of lye to make liquid soap from scratch.

  3. Pinned this. I’m interested in soap-making, but I’ve been worried about the lye piece. I haven’t considered hot process, either!

  4. I know this post is older, but what can I use to replace the coconut oil? I am allergic to coconut in any form. Thanks!

  5. Hi. I enjoy reading your articles. I have a lot of lard. Do you have a nice recipe using lard? Does it make inferior soap? I never see recipes using lard.

    1. I don’t personally use lard anymore, but I have in the past. It works just as well as tallow does in the soap. Let me know how you like it!

  6. Just watched your video, nice. I make cold press soap but this way looks easier, love not having to wait 6 weeks for the soap to cure, thanks. Have you tried making herbal infused oils for your soap, I have a herbal CSA and one of the products I make is herbal soaps. I thinking the hot press would work just fine.

  7. Thanks so much for the video and instructions. I want to start making my own soap. Too many chemicals in the stuff that “passes” for soap today. I have ordered my ingredients and will be ready to go when they arrive. 🙂

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