Soap making with lye and fat

Making your own soap entails combining a strong lye (alkaline) solution with solid fats and/or liquid oils resulting in a chemical reaction known as saponification.

The web is awash (deliberate..) with DIY soap recipes however many are difficult to follow fully, lack clear instruction or just simply do not work. The following recipe is fully credited to:

This website has a tonne of info on a wide range of soap making methods and recipes. For a starter use one of their simple soap making recipes to get to grips with the processes and tools.

On a recent Woodland Wayer course we used the following recipe from the above website:

  • 16 oz. olive oil
  • 8 oz. coconut oil
  • 8 oz. palm oil
  • 10.5 oz. water
  • 4.5 oz. lye
  • 1.4 oz. of fragrance oil (we substituted birch tar)

In previous years we have added birch oil to the soap recipe to give the finished bars a coal tar like smell. This year we used birch tar that had been condensed down a little which really gave the soaps a powerful smell, added to which the many benefits of skin health this wonder product contains.


Well mixed birch tar scented soap being poured into clay moulds.

The negative aspect to the above recipe is of course the use (and therefore continued support/demand) of palm oil which can cause huge amounts of environmental damage in its production so try to find palm oil from an environmental friendly source. This recipe does work well and once you get the idea  other hard and liquid oils can be substituted freely – the above olive oil for example could just as easily be the cheaper vegetable oil.


Step 1

Mix the lye solution first and set it aside to cool.

Be extremely aware of risk to the skin and eyes when handling lye solutions – gloves and glasses are recommended and children should most definitely be supervised. Make sure pets cant get access to the liquid also.

Step 2

Weigh and heat your solid oils until completely melted. Add the liquid oils to the melted solid oils. A set of electronic kitchen scales is particularly useful and more accurate (which is very important) than pan scale equivalents.

Step 3

When both the lye and the oils are at about 47 – 44 degrees celcius (100 – 110 F) SLOWLY pour the lye solution into the oils. Stir with a stick blender, alternating short blasts with the blender and stirring. Another hazard here is getting the fats or the lye too hot and combining whereby mixing them causes a violent reaction which could cover you in caustic liquid! Take care and use a thermometer to get it just right.

Step 4

Mix the soap until it reaches what is known as a light trace. Anyone who has made jam will be familiar with the trails left by the spoon in the jam when it is approaching a setting point – this is what you are looking for in the soap – just the faintest lines left behind the spoon or whisk (usually occurs after 5 – 10 minutes whisking with this recipe).

Step 5

Add the fragrance oil. You can buy all sorts of concentrate fragrance for soap making but why not experiment with some bushcraft alternatives!? Mix them into the soap thoroughly.

Step 6

Pour the raw soap into your mold and let it sit for 12-24 hours. The addition of a small length of rope allows you to hang your soap when out in the woods. We tried to rely more on the woods and quickly made some improvised moulds from ground clay we dug up – these worked an absolute treat although I would say slowed down the hardening process slightly from when I’ve poured soap into plastic moulds…


Clay moulds ready whilst ingredients being weighed and mixed.

Step 7

Remove it from the mould and slice into bars. Let it cure an additional 2-4 weeks. The curing is an important step as the young soap still contains unreacted lye chemicals making it too caustic on the skin. allowing it to cure helps the lye continue to react with the fats and oils producing a more balanced soap i.e. enough caustic action to clean with enough fat to moisturise.


Birch tar soap on a rope set after about 24 hours in a clay mould.

Field hygiene is critical in bushcraft and certainly for longer stay durations in the woods or on expedition and this aspect is often brushed over quickly or completely absent from many outdoor texts – learn to make your own cleaning products from nature and more conventionally at home with scales but be aware of the associated risks involved with handling caustic liquids.

Adam Logan.



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