By P&J Trading


Over these past couple months, we have discussed two different soap making processes which you can find here: Melt & Pour and Cold Process. This month, we are diving into a third process known as hot process. Follow along below to learn all about the fundamentals of this soap making process from our P&J Family! 


Similarly to cold process, lye and hot oils are mixed together to start the saponification procedure in hot process. However, in hot process, the mixture is then placed into a heating source such as a crock pot or double boiler. This additional heating technique speeds the saponification process and cooks the soap before it is placed into the mold. The heating method drastically cuts down the cure or wait time of the soap. The main difference between CP and HP is the temperature. In CP, the soap must sit for several days to harden and set. Whereas in HP, the soap can typically be used within the next day.


We have created pros and cons list for hot process from our crafters below: 


  • HP has a very quick turnaround and can typically be used the next day. Although, it is said that a longer cure time means a more sturdy bar of soap.
  • Since additives and fragrances are placed in after the soap is cooked, they do not come in contact with lye. This means the fragrance tends to have a stronger aroma and the additives hold better. The additives also stay closer to its original shade. For example, pink flower petals should stay pink instead of fading into a different color.
  • There is no seizing, cracking, or soap ash as the scent is added after the saponification process.
  • This type of soap making allows for complete customization of all ingredients such as oils, fragrances, and additives.


  • Depending on how you personally want your soap to look, some do not like that HP has a more rustic, refined look.
  • Alongside the refined look, it is more difficult to add designs such as swirls or layering.
  • Adding colorant can be difficult and requires experimentation to see what you like.
  • The soap expands, as it cooks, and can overflow in the heating source if you are not careful.
  • It can be hard to add ingredients such as milk as it is too hot during the cooking stage.


Here at P&J, we compiled a basic list of some ingredients/quick tips for HP:


  • Hot process method requires a crock pot or double boiler as a heat source. You must make sure when making hot process soap, that your recipe does not fill up the source more than halfway. The soap tends to expand and can overflow!
  • It is imperative to wear goggles, gloves, and long sleeves as it can be dangerous to work with various substances such as lye.
  • Various other tools are needed such as a steel container to measure lye, a scale, a stick blender, molds, and spatulas.
  • When developing your lye mixture, never pour the water into your lye as this may cause a dangerous reaction.
  • Adding the scent can be done after the saponification which will strengthen the aroma. Luckily, our P&J Fragrances have a higher flash point and you do not have to worry as much about a scent-fade.         
  • When adding the colorant, you can either do this at a light trace before the cook so you can stick-blend or after the soap has cooked. Both take experimentation until you get the shade you want.

As always, we recommend experimenting with different soap techniques until you find your perfect soap!