What Is The Heat Transfer Method In Soap Making and How Can It Save Me Time
The Heat Transfer Method for Cold Process Soap Making
The heat transfer method is simply a slightly different way of preparing your ingredients before you make your soap.
Normally with cold process soap making we melt our butters and oils first, mix up our lye solution, let it all cool down and then add our liquid oils before mixing it all together and make the soap. The heat transfer method works the other way round.
Instead of waiting for your lye solution to cool down, you use it while it is still hot. When lye is first mixed it is usually around 200°F. Rather than letting that heat go to waste, we can use it to melt our hard butters and oils. I have found it to be a game changer. It is simple, it works really well and it removes a lot of hanging around waiting for things to cool down before you can start making your soap.
I know a lot of people get quite worried about temperatures when they are learning cold process soap making. There is a whole raft of misinformation online and you may well have seen advice about using your oils and lye between certain temperatures or making sure they are within ten degrees of each other. Whilst that information is not wrong, (and I always give new soap makers guideline temperatures to aim for as it is then one less thing for them to think about), in my experience there really is no right or wrong with this. It is all very much personal preference.
Over the years I have used cold lye solution, hotter oils, cooler oils and obviously the heat transfer method. I have used ice instead of water so that I can use my lye solution straight away and in the summer - fridge cold water so it doesn't take quite as long to cool down.
They all give the same results. It really is more about knowing what to expect and finding a method that works for you.
How to use the heat transfer method when making soap
The process itself is very straightforward.
First I weigh out my hard butters and oils. That might be something like coconut oil along with cocoa butter or shea butter.
Then I mix up my lye solution. (Remember to wear your gloves and goggles).
As soon as the lye solution is ready I carefully pour it straight onto the unmelted butters and oils. Then all you do is stir. Keep stirring while the heat from the lye solution melts the oils and butters.
Sometimes it melts quite quickly. Other times it takes a little while. That is completely normal and a lot can depend on the ingredients you are using and the ambient air temperature.
It is absolutely fine to leave it for a few minutes to soften everything up and do its own thing while you go off and do something else. Just make sure it is safe from pets and children, then come back and give it another stir. If it takes ten or fifteen minutes that is not a problem at all.
A couple of practical things to be aware of
There are a few situations where you might need to make small adjustments. For example, when I used to make soap for dogs my recipe was one hundred percent coconut oil. In the winter that coconut oil could be very cold and is solid. In that situation I would sometimes partially melt some of it first just to give it a bit of a head start. Otherwise you are asking the hot lye solution to melt quite a lot of very hard oil.
If you are using cocoa butter you will need to make sure it is cut into smaller chunks because it is really hard with a relatively high melting point. You can't use this method with one great big chunk of cocoa butter and expect it to melt easily. The cocoa butter discs are brilliant for getting around this, although they are not always the most economical option now the price of cocoa butter has gone up. If you only have a block of cocoa butter, what I tend to do is put it in a bag, lay it on a tea towel and then use a screwdriver to stab it and break it into smaller chunks. It might sound a bit odd but it works really well.
Finishing your cold process soap as normal
Once the butters and oils have melted, I then add my liquid oils. After that I carry on exactly as I normally would. I will use the stick blender to mix the soap to emulsion or trace, depending on what I want, and then continue with the rest of the process as usual. That is it.
I like this method so much as it just makes the whole process feel quicker and easier. You don't have to spend time waiting for everything to cool down. You can weigh your ingredients, make your lye solution and get on with making your soap.
My experience using the heat transfer method
If you are particularly worried about trying this method, just give it a go with a small batch. The mixture is not going to turn into soap until everything is melted and you start blending it, so you have plenty of time to work with it.
I have never yet had a batch go wrong using the heat transfer method and I used it in my hands on soap making classes sometimes as well, both for beginners and more experienced makers. (The experienced makers who had never tried it before LOVED it btw).
The largest batch I ever made this way was 4.8 kilograms of ingredients, which made four soap loaves. I didn't go larger simply because I did not have equipment big enough to do bigger batches in one go but I would have done so if I could. My message here being that it works just as well if you are making a larger batch as it does for a small one.
It also works whether you are a business or a hobby maker. And it can be particularly useful if you suddenly realise you have forgotten to prepare everything in advance and you need to make a batch fairly quickly.
I am hoping I have convinced you to at least give it a go - I promise it is super simple and may well change the way you make your soap forever. Caveat - don't use this method with milk, you will scorch it, Stick to using frozen milk cubes for that.
If you do try it, I would genuinely be interested to hear how you get on and if you are still unsure about soap making in general or would like to know more check out my Mini Soap Suite Membership. I cover everything from Beginner Soap Making right through to doing fancy swirls (including some tutorials that use this very method) and there are a number of other product making tutorials in their too.
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