Soap school – why we’re using the heat transfer method to make cold process soap

Soap school – why we’re using the heat transfer method to make cold process soap

You may have seen our last videos where we use the heat transfer method to make cold process soap. If you haven’t, they’re here, and here.

Basically, the heat transfer method stipulates that you add your lye water solution to your hard oils to help melt them, and simultaneously cool down the lye water solution to room temperature. This decreases the time it takes to whip up a batch of soap.

There are both positive and negatives for this method, which I will outline in this post.


  • Production time is decreased. By using the heat transfer method, you don’t need to let your lye water solution get to room temperature, or attempt to use ice water baths to cool it in order to make your soap. You don’t need to remember to try and make it the night before a soaping day (which let’s face it, sometimes after a hard day you just don’t have the energy to do that), and you don’t need to warm up your hard oils to liquid viscosity, and then let it cool down to within 10 degrees of your room temperature oils, in order to start making soap. All in all, the heat from the chemical reaction of lye to water helps melt the hard oils (which are better at room temp prior to soaping anyway), and cool the solution at the same time.
  • You can start soaping immediately. This is great if you have to make multiple soaps in a day, or have other errands you need to get to. Making soap using this method hastens the time spent soaping.
  • You can get to medium and thicker trace quicker if you enjoy soaping in that range.
  • If using clays, micas or other colours, this leaves an entire half of a batter in your soft oil mix where you can pre-mix these additives. I’m definitely more into really rustic, traditional and natural looking soaps, so even my swirls and multi-coloured soaps will be less elaborately designed. So, this works for me because I often use clays in my soap mixtures and I can ensure that it is well blended before adding it to the hard oil/lye mix.


  • Light trace is much more difficult to achieve. If you prefer soaping within light trace and then getting to medium, then this method may not be suitable for your soap making style.
  • You have to work quickly. With a moderate soap batter, it will hasten trace.
  • If you’re an ‘on the fly’ soap maker, (which I doubt many are), then this method won’t work for you. Everything you want to use in your soap needs to be weighed out and ready to use. There is little time for changing your mind once you’ve committed.
  • Your design for a soap using heat transfer method may be limited if the batter moves to trace quicker.

So you see, this method has its merits especially if you have a specific design style or batter in mind. It doesn’t work for all methods, and I certainly will consider using the traditional method if I have a need for it, but for now I am enjoying this method as it ensures I can fit in making a few extra batches when time is limited.

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