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Soap Basics – Hot Process

I have a craft show coming soon and not enough product. OH No!!! What am I going to do? The answer lies in Hot Process. While it is a little more labor intensive these soaps saponify significantly faster. In fact you can use them immediately, but you will want them to harden up so they last longer (about 2-4 weeks). Chemical reactions need energy and heat is a form of energy. So we are just speeding up the chemical reaction soap undergoes by adding energy via heat. You can do this with a crock pot, stove top, or even in the oven. The most important thing to remember is you CAN NOT walk away. So put the kids to sleep and let’s begin.


Crock Pot Hot Process

This can be done in the oven or on the stove top as well but I prefer the crockpot.

Materials needed:

  • Crock pot (use a pretty big crock pot because you want to only fill it half way so it doesn’t volcano over the sides)
  • Oils (you can use any recipe you want with this)
  • Lye
  • Water (I suggest distilled water)
  • Stick Blender (this is the easiest and safest)
  • Colorants and Scents (Cold process approved stuff is the best, most wont say hot process)
  • Soap Mold
  • Safety Equipment (goggles, gloves, long sleeves, apron)


  1. Get it together. Make sure you have everything you need before you begin. This process involves fairly constant monitoring so running to get something is a bad idea. Make sure your mold is ready, lined if need be. Don your safety equipment and let’s begin.
  2. Pre-measure everything. I like to measure out my oils in one bowl, my distilled water in another, my lye in another, and my colorants and scents in others still. Having it all measured and ready makes the process way simpler.
  3. Mix your lye-water and oils. I like to do this all in the crock pot so I can start the cooking process.I melt all my oils in the crock pot first once they are melted  I blend the oils first to make sure they are evenly dispersed then mix the lye and water in a separate bowl till the lye is completely dissolved. Remember lye to water never water to lye. Unlike cold process it does not matter what temperature your oils or lye water is at when you mix them just that all your oils are melted down. So once the lye is dissolved mix it in the crockpot with the oils. Turn your crockpot on low. (If you are using a newer crock pot, If your crockpot is older they do not get to as high of a temperature so you may have to turn it to high)
  4. Stick blend till trace. Make sure that you have space in your crock pot the mixture will expand. I recommend only filling half way. I have split my mixture between two crock pots before for this reason.

As you see in the video you can see where you stirred it. It holds it shape. Light trace is where it is just barely visible as you stick blend the trace will get even more noticeable. Once you get to trace you can stop blending.


If you want to try something I absolutely love you can keep blending and do what is called Stick Blending Hot Process (SBHP).  For this you will still follow the steps but will continue blending which will speed up the process. Be warned that many stick blenders can not blend for the length of time that it takes to SBHP. If your blender starts to get hot please stop don’t fry your stick blender. I like to switch between two different stick blenders and give them breaks which wont hurt the process.

5. The stages of Hot Process. As your soap cooks it will go through several stages. Sometimes the stages will not be very noticeable so you need to pay close attention especially your first time so that you learn the steps and can identify when it is about to volcano which we will discuss shortly. If you are not (SBHP) it is important to conserve  water from evaporation. Do not remove the lid on your crock pot constantly. Also spoon stirring is not effective enough to decrease cook time and will actually lengthen the amount of time it takes.

The first stage is commonly referred to as Applesauce or Separation this is where there is solid and liquid content. It may look crazy but is completely normal.

Next your soap will come back together and start to rise or Volcano. This is why we only fill the crock pot half way. It can expand quite a bit. If you fear it will overflow then now is the time to stir like crazy, but most of the time it will not overflow and will be fine. Be prepared because the mixture can volcano very quickly.

The last stage is the vaseline stage or mashed potatoes stage. At this stage your soap is ready. It has a waxy consistency if you touch it. I have heard people say to touch the soap to your tongue to see if it’s done if it zaps you it needs to cook longer. I would rather not be “zapped” by soap. You can purchase ph tests, but I think that once you can identify the stages accurately this is not necessary. Once the soap is at the vaseline stage even if the lye is not fully saponified it will continue to saponify while the soap cures. Once at this stage it wont take long at all. I recommend a week to two so that the soap hardens up well, but you could use it immediately if the lye is fully saponified.


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At this point you can add scent and color but work quickly you will need time to mold the soap and it will set up fast. I add a tablespoon of yogurt per pound of soap. This makes the soap more “fluid” and easier to work with as well as a cleaner look. Without the yogurt it has a very “rustic” look. With practice you can do all kinds of swirls and tricks even piping (like cupcakes).

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