What oils can you use to make cold process soap?


What oils can you use to make cold process soap?


Well, in theory, any oil when mixed with lye will saponify and produce soap. But there are several reasons that some oils are used more than others.

The “perfect” soap bar needs to be long lasting but not too hard, cleansing but not drying, nourishing without being soft and not too expensive to make.

In reality what we want from our soaps is different, you may want a hard as rock bar with creamy bubbles or a soft gentle bar with big fluffy bubbles.

So what is the secret to creating your perfect soap formula?

You need to understand the properties and peculiarities of the oils and get to grips with fatty acids. It doesn’t need to be as complicated as it sounds if you follow some simple rules.

Let’s start with the basics first soft, hard and brittle?  What does that mean?

Soft oils

A better description would actually be liquid oils, as they are generally oils that are liquid at room temperature such as olive oil, castor oil, sweet almond, etc.  As expected soap made from a high percentage of these oils will be on the softer side.  But there is an exception; olive oil.  Soap made from a high percentages of olive oil may feel soft when straight out of the mould but once cured it makes a really hard bar of soap.

If making soap made with high percentages of soft oils and your soap feels sticky when unmoulding, just leave them in the mould a day or two longer .

Soap made with soft oils, especially olive oil, is slower to trace , especi

ally extra virgin oils, but this makes them perfect for swirling as you have more time to play with colour and fancy techniques.


Hard oils

Guess what?  They’re not actually that hard! Hard oils refers to oils, fats and butters that are solid but still soft enough to scoop at room temperature such as palm oil, coconut oil, mango butter and shea butter. Generally hard oils make a hard bar of soap. You’ll probably need to soap at a higher temperature though, to ensure your hard oils are fully liquid when mixing.

Brittle oils

As the name suggests these are the really hard oils, you know the ones that require a bit of extra effort chipping away to break them up.  These generally include palm kernel oil and cocoa butter.  Brittle oils will make a hard bar of soap.

Soap made with higher percentages of hard and brittle oils will be set faster and so quicker and easier to unmould, but it also means they are harder to work with if you want to do anything too advanced.

If you want to try single cavity moulds then its best to use a recipe high in hard and/or brittle oils to make unmoulding the soap easier.

Now the science bit…..

Now I’m no chemist, but learning a bit about the science of soap making can make all the difference when formulating your recipe. Soap itself is a chemical process, a reaction called saponification, the mixing of alkali salts (lye) with fats (oils).  So every time you make up a new batch you are performing your own little science experiment.

Now as I’ve already mentioned I’m not a scientist, I’m maker, so if you’re looking for a science lesson you’re on the wrong page. I will however give you some basic info that hopefully explains enough, and if you want more info, just ask…… I may not know the answer but I probably know someone who does!


Fatty Acids

Oils are made up of a combination of fatty acids, and it’s these that will ultimately determine the characteristics of the finished soap bar.


Lauric acid

This is what creates a hard, highly cleansing bar with lots of fluffy lather.

Beware of using too much though, as it is extremely cleansing it will strip oils from the skin leaving it dry and fluffy lather washes away quickly.

Oils high in lauric acid are coconut oil, palm kernel oil and babassu oil.


Myristic acid.

These 3 oils, coconut oil, palm kernel oil and babassu oil, are also high in myristic acid, which has many of the same attributes, a hard bar with good cleansing properties and abundant lather. But as with lauric acid these attributes come with issues too, it will leave skin feeling dry and the fluffy lather washes away quickly.


Linoleic acid

Will add moisturising properties to your soap. Although all soap is cleansing this is less harsh and offers conditioning lather.  The downfalls of linoleic acid is its reasonably short shelf life, too much of these oils could cause dreaded orange spots (DOS)

Oils high in linoleic acid are soybean oil, grapeseed oil, sunflower oil and safflower oil. To a lesser extent it is also present in rice bran oil, canola oil, sweet almond oil and apricot kernel oil.


Linolenic acid

Crazily similar in name and properties to linoleic acid, linolenic acid also provides conditioning lather with mild cleansing.

Oils high in linolenic acid include hemp seed oil.


Oleic acid

Although this will add conditioning properties to your soap it will add little to no bubbles. It can make the soap feel slippy though.

It’s present in many butters and oils including shea butter, cocoa butter, mango butter, avocado oil, rice bran oil, canola oil, sweet almond oil, apricot kernel oil, olive oil, high oleic sunflower oil, high oleic safflower oil, jojoba oil, macadamia nut oil. In lesser quantities it is also in palm oil, soybean oil and grapeseed oil.


Palmitic acid

Adds a stabilising, creamy lather and hardness to a bar, beware not to add too much as it can be drying.

As expected palm oil is high in palmitic acid, it is also present in avocado oil, neem oil and rice bran oil


Ricinoleic acid

Is great for adding a bit of luxury with creamy conditioning lather that is stable.

Primarily it’s only found in castor oil.


Stearic acid

Adds a creamy lather and hardness to a bar, beware not to add too much as it can be drying.

Stearic acid is found in kokum butter, mango butter, shea butter and cocoa butter.

To me soap making is an art and not just a science so you have to experiment. Once you know the basics of why the oils and butters act in certain ways you can start work on formulating your perfect recipe. The art is getting the right percentages of the oils into your formula. For us at the soap kitchen its approximately 50% olive oil, high in Oleic acid it is conditioning and creates a hard soap,  30% coconut oil, high in lauric acid creating a hard, highly cleansing bar with lots of fluffy lather and 20% palm oil high in palmitic acid which adds a stabilising, creamy lather.

The final thing to bear in mind, and for some the most important, is the cost. If you want to produce a bar of soap to sell it needs to be cost effective. There is no point making a beautiful bar of soap with expensive luscious oils if your customers are not willing to pay the price tag.

The most efficient way to do this is to use the luxury oils as enrichments instead of base oils. Add a small amount (around 15ml per kg of soap base) to the soap at trace.

Click HERE to download the oil chart

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1 thought on “What oils can you use to make cold process soap?

  1. Nice article and thank you for the oil chart, it makes life a little easier having them all in one place.

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