Choosing Oils for Soap Making:
Oil types and fatty acids, balancing recipes and Soapcalc explained.

 
Elly's Everyday choosing oils for soap making

There are many possibilities when it comes to choosing oils, butters and fats suitable for soap making. It is a complex subject and the best oils to use are determined not only by what makes a good bar of soap, but what is accessible and affordable in your location, taking into consideration environmental, ethical and sustainability issues and your own personal preferences.

This list of oils used for soap making around the world (that many of you generously contributed to) is a fascinating insight into the variety of oils available in different locations across the globe.

 

A Video Talk on Choosing Oils for Soap Making

In my video on Elly’s Everyday Soap Making YouTube channel, I provide an overview of the main considerations to be made when choosing oils for soap making.

On this page I provide a summary of the video content, including links to the resources mentioned and some further detail about usage rates of the different fatty acids in soap making oils.

If you haven’t seen the video, you can view it in YouTube by clicking here or on the thumbnail image below.

*If you are new to soap making and would like a demonstration of how to use Soap Calc to calculate a soap recipe, you can see my video for that here.

 

Overview

In the video (and below) I talk through:

The eight most common fatty acids found in oils and fats used for soap making

The qualities of the different fatty acids in terms of:

  • Saturated or unsaturated fatty acid

  • Lathering ability

  • Cleansing properties (strong/drying or mild)

  • Hardness and longevity

  • Speed of saponification

  • Examples of oils

What makes the best soap?

What else is important?

Soap calc ranges explained

Further reading and resources

 

The Main Fatty Acids found in Oils and Fats used for Soap Making

NOTES:

  1. Most oils and fats are composed of a number of different fatty acids, giving them a specific ‘fatty acid profile’.

  2. Usage rates given are a guide only. The suggestions below are based on my personal experience and the research conducted by Kenna from Modern Soap Making in her article here.

  3. Let your soap calculator guide you. Once your recipe is calculated it will tell you the combined fatty acid profile and you can make adjustments from there. See my video and the final section of this page for tips on understanding and evaluating your recipes using Soap Calc.

Lauric acid

  • Saturated fatty acid

  • Contributes abundant, fluffy lather

  • Strong cleansing (can be drying)

  • Makes hard but highly soluble soap

  • Fast saponifying

  • Eg. Coconut oil, palm kernel oil (not palm oil), babassu oil, laurel oil, cow and goat milk fat

  • Suggested usage rate: Up to 20%

Myristic acid

  • Saturated fatty acid – often found in combination with lauric acid

  • Contributes abundant, fluffy lather

  • Strong cleansing (can be drying)

  • Makes hard but highly soluble soap

  • Fast saponifying

  • Eg. Coconut oil, palm kernel oil, babassu oil, cow and goat milk fat

  • Suggested usage rate: Up to 10%

Palmitic acid

  • A very common saturated fatty acid found in many plant and animal fats

  • Contributes moderate, stable, creamy lather

  • Moderate cleansing

  • Makes hard, long lasting soap

  • Fast saponifying

  • Eg. Palm oil (not palm kernel), tallow (beef fat), lard (pork fat), other animal tallows, emu oil, cocoa butter, shea butter, mango butter

  • Suggested usage rate: Up to 25%


Stearic acid

  • Saturated fatty acid, often in combination with palmitic acid

  • Contributes low, creamy lather

  • Low cleansing (mild soap)

  • Contributes to hard, long lasting soap

  • Fast saponifying

  • Eg. Kokum butter, sal butter, cocoa butter, shea butter, mango butter

  • Suggested usage rate: Up to 15%


Ricinoleic acid

  • An unsaturated omega-9 fatty acid and hydroxy acid

  • Contributes low, creamy lather (assists lather due to solvent properties)

  • Low cleansing (mild soap)

  • Soft, sticky soap if used in high amounts

  • Slow saponifying

  • Eg. Castor oil only – has 90% ricinoleic acid

  • Suggested usage rate: Up to 10%


Oleic acid

  • Monounsaturated fatty acid

  • Low lather

  • Low cleansing (mild soap)

  • Softer, more soluble soap (not as long lasting)
    *Note 100% olive oil soap makes a very hard soap if made well, and can remain hard in use after a long cure and under dry conditions, otherwise it can be quite gooey!

  • Slow saponifying

  • Eg. Olive oil, sweet almond oil, apricot kernel oil, canola (rapeseed) oil, macadamia nut oil, avocado oil, peanut oil, rice bran oil, neem oil, high oleic sunflower and safflower oils

  • Suggested usage rate: 20-50%


Linoleic acid

  • Polyunsaturated Omega 6 fatty acid

  • Low lather

  • Low cleansing (mild soap)

  • Soft soap

  • Reduced shelf life and prone to Dreaded Organge Spots (DOS)

  • Slow saponifying

  • Eg. Sunflower oil, safflower oil, grapeseed oil, cottonseed oil, soybean oil, hemp seed oil, corn oil, sesame oil, wheat germ oil

  • Suggested usage rate: 5-20%

Linolenic acid

  • Polyunsaturated Omega 6 or Omega 3 fatty acids (usually with linoleic acid but in lesser amounts)

  • Low, silky lather

  • Low cleansing (mild)

  • Soft soap

  • Reduced shelf life and prone to DOS

  • Slow saponifying

  • Eg. Hemp seed oil, walnut oil, linseed/flaxseed oil

  • Suggested usage rate: 0-2%

 

What makes the best soap?

A blend of fatty acids is best!

FOR:

  • Big lather: Pay attention to lauric and myristic (but beware, they are also high cleansing and make soluble soap)

  • Longevity and hardness: Palmitic and stearic are the key fatty acids to look for

  • Oleic: Contributes mildness with a good shelf life

  • Linoleic & linolenic: Contribute mildness but have shorter shelf life and possible DOS

  • Other factors:

    • Superfat - A higher superfat can counteract some of the drying effects of high cleansing soap formulations

    • Water type - Hard water can inhibit lather. Soft water is best for soap making.

    • Added sugars - Sugars can boost lather and increase speed of saponification.

    • Added salts - Salts can make a harder bar but can also inhibit lather in high amounts.

 

What else is important?

What you have available to you

  • Do you have any oils produced abundently in your country?

  • What is available to you from local suppliers?

What you can afford

  • Buy what you can afford, but think first before buying solely on price

  • Is someone else paying the cost?

  • Is the producer being paid fairly?

  • Are there environmental costs involved?

  • Would you consider using recycled oils? Used cooking oil? Waste animal fats?
    (Many people make soap with used cooking oil. As long as you know what type of oil it is you can calculate a recipe with it!)

Environmental and ethical issues

  • Palm oil and deforestation - Many soap makers choose not to use palm oil due to deforestation taking place in many countries as a result of high global demand for palm oil (mainly for processed food products and skincare/factory soap products and cosmetics).

  • Carbon emissions and trade inequities with imported products - How far do your oils need to travel to get to you? Do you have a local alternative? Are you buying from sustainable, fairly traded sources where possible?

  • Animal fats or vegetable only soap?

Packaging

  • What packaging does your oil/fat products come in?

  • Can it be recycled or reused?

  • Is there another product that is packaged more responsibly or minimally?

  • Can you collect your products locally rather than have them packed for shipping?

Your personal preferences

  • Do you have favourite oils that you love?

  • Do you want simple 1-3 oil recipes or more elaborate, complex formulations?

  • Do you want to use basic and more affordable ‘everyday’ oils and fats or do you prefer luxury oils in your recipes?

 

Soap Calc Explained

The information in this section is guided by Soap Calc and articles on the Classic Bells website, by DeeAnna Weed (see references below).

As you can see in the image below (using my Coffee Soap recipe as an example), Soap Calc provides an analysis of the calculated soap recipe using fatty acid values from the recipe measured against Soap Calc’s suggested quality ranges.

The values Soap Calc assesses are:

  • ‘hardness’

  • ‘cleansing’

  • ‘conditioning’

  • ‘bubbly’

  • ‘creamy’

  • ‘iodine’

  • ‘INS’

But what do these words mean? How are they calculated?

Elly's Everyday soap calc example explained

Here’s an overview:

Hardness
Calculated on the combined amount of lauric, myristic, palmitic and stearic acids in the soap recipe. But, remember that lauric and myristic acids make soluble and high cleansing soap, so it may be more useful to look at the palmitic and stearic numbers to get a true gauge of the hardness and longevity of your soap recipe.

Cleansing
Calculated on the combined amount of lauric and myristic acids in the soap recipe. This makes perfect sense as these two fatty acids are known to create high cleansing/drying soap when used in high amounts.

Conditioning
Calculated on the combined amount of oleic, linoleic, linolenic and ricinoleic acids in the soap recipe. This also makes sense as these unsaturated fatty acids all make mild soap which could be said to have ‘conditioning’ qualities (though it is still soap, it will not add any moisture to the skin, so I think this term is a bit misleading).

Bubbly
Calculated on the combined amount of lauric, myristic and ricinoleic acids in the soap recipe. This seems accurate as lauric and myristic acids both contribute to a very bubbly lather, and ricinoleic (castor oil) assists lather due to its solvent properties. Note that these fatty acids are all very soluble when made into soap though, so if you recipe rates high on the ‘bubbly’ scale it may not last very long in use.

Creamy
Calculated on the combined amount of palmitic, stearic and ricinoleic acids in the soap recipe, which makes sense as palmitic and stearic acids are known to contribute a moderate, creamy lather and ricinoleic assists lather generally.


AND, the final two criteria (which I ignore completely):

Iodine number
This number is generated from values known through oil testing where iodine is reacted with fatty acids to determine the amount of unsaturated fat there is in a given oil/fat or combination.

  • High iodine number - High level of unsaturated fats/liquid oils

  • Low iodine number - Low level of unsaturated fats/liquid oils (higher unsaturated fats)

INS
Stands for ‘Iodine Number Saponification’ and is the saponification value of the oil/fat/blend minus the iodine number.

 

Evaluating single oils and whole soap recipes

One of my favourite ways to use Soap Calc aside from calculating the lye amounts for my soap recipes is to use it to evaluate the fatty acid profiles of single oils. This can be a very useful technique if you have limited oils available (or would like to choose your soap making oils and stick to them) and you would like to evaluate which oils will perform best in your recipes, according to the soap qualities you prefer.

As you can see in the example pictured, selecting individual oils (eg. coconut oil) in Soap Calc (and other soap calculators) displays the full fatty acid profile of the particular oil, making it a lot easier for the soap maker to evaluate oils they are not familar with and might be considering adding into their soap recipes.

Elly's Everyday soap calc example explained 2
 

I hope this has helped you!

Well, that’s about it for now, folks. I’ll keep this page updated as needed.

Here’s the link to the video again if you haven’t seen it (highly recommended, much more discussion there than is possible on a web page).

Please remember I am a home/hobby soap maker and it is advisable that you always do your own research on the science of soap making before relying on information provided by others on websites/blogs/YouTube videos. This resource is intended as a guide only. Please see my full disclaimer here.

Enjoy your soap recipe formulating!

Elly 🌻