Soaping up a stink

A summary account of silver for the governor written in Sumerian Cuneiform on a clay tablet. From Shuruppak, Iraq, circa 2500 BCE. British Museum, London.
A summary account of silver for the governor written in Sumerian Cuneiform on a clay tablet. From Shuruppak, Iraq, circa 2500 BCE. British Museum, London.

Along with many other facets of human civilisation, soap making originated in ancient Mesopotamia. A Sumerian tablet (much like the one shown here) – dated to around 2800 BC – is our earliest evidence, describing a concoction used to cleanse both the skin and textiles. In this recipe, oils were boiled with alkali potash, sodium, resins and salt.

Other archaic texts and testimonies are variations on the theme, with the Ancient Egyptians whipping up a rich and rather tantalising mixture of fuller’s earth, natron (sodium chloride/ carbonate/ bicarbonate/ sulphate) and crushed lupins to clean bodies both dead and alive. Soap – in a crude sense – was born. But though certain folk had clearly grasped soap’s degreasing, antimicrobial powers, its manufacture had not yet become an established industry. When barbarian invasions brought down the Roman Empire, society lost much of its refinement and we became, once again, the great unwashed. 

But while soap making in Europe  declined, our Arab cousins were busy perfecting the craft. They were the first to add lime to the ash lye – hence the Arabic ‘al-qali’ or ‘ash’ , the root of our word ‘alkali’. If the archaeological evidence is to be believed, it wasn’t until the middle of the 8th century AD when Europeans began lathering up again. Soaping flourished in places such as Marseilles, Savona, Genoa and Venice, no doubt inspired by increased contact and trade with the Middle East.

For all amateur alchemists out there, the saponification process is one of life’s minor miracles. As the matter changes from one state into another, it’s hard not to feel there is magic at work. But of course, it’s not magic, it’s basic chemistry. In the words of L’Oreal, “here’s the science…”.Without going into forensic detail, the process is best described thus: fatty acid meets strong alkali, creating a neutral salt. The fatty acids (triglycerides) are the butters and oils – anything from animal tallow to vegetable oils such as olive, coconut, sweet almond etc. The strong alkaline solution (‘lye’) is usually sodium hydroxide dissolved in water. Yes, that’s caustic soda.

In the chemical reaction, triglyceride fats are first hydrolysed into free fatty acids, before combining with the alkali to form a basic soap. This crude stuff contains soap salts, excess fat and alkali, water and liberated glycerol or ‘glycerin.’ This glycerin by-product is a superbly useful softening agent. In modern industrial soap making this lovely glycerin is typically removed and re-sold to other industries including pharmaceutical, personal care and food processing. Hence why many people find soap too drying for their skin.

This month I decided to try my hand at traditional cold process soap making, using a basic recipe for a scrubby salt soap bar and adding my own ingredients (kelp powder, essential oils…) to jazz it up a little. Perhaps I shouldn’t have… 

Before I give you the recipe, a quick disclaimer: if you’re a beginner and fancy giving this a go, please read up on the subject these safety guidelines and get properly informed before you start.     

Soap safety. A glamorous look 


Makes approximately 1.4 kg/ 3lb soap.


700g coconut oil (-luxurious, creamy and softening)
100g cocoa butter (-softening and moisturising, to counteract the drying effect of the salt on the skin)
200g castor oil (-like glycerin, it’s a powerful humectant that draws moisture to the skin while also creating large, thick bubbles in cold process soap)

330ml purified or spring water (-not mineral water, to stop it messing with the chemistry bit)
157g sodium hydroxide (-100% pure, mind)

400g fine sea salt (-not too coarse, you don’t want your soap to be too scratchy)
50g kelp powder (-packed full of skin-nourishing nutrients including Omega-3, and vitamins B2, B6 and B12, the kelp particles work with the salt to gently exfoliate and remove dead skin)

10ml rosemary essential oil (stimulating, antimicrobial)
5ml lemon essential oil (refreshing, uplifting)
Plus a bit of dried bladderwrack seaweed (-for decoration)

If you want to experiment with different base oils, you will need to adjust the amount of lye. Run your numbers through one of these online calculators to get the measurements right.


  1. Weigh the coconut oil and cocoa butter, cut into small chunks, and the castor oil. Put in a plastic bucket and set aside.
  2. Put on your rubber gloves and goggles.
  3. Weigh the water in a new plastic bucket. Set aside.
  4. Weigh the sodium hydroxide in a jug. Set aside.
  5. Weigh the sea salt and powdered kelp. Measure out the essential oils and add them to the sea salt and kelp. Stir and set aside.
  6. In a very well-ventilated area – wearing gloves, masks and goggles – gently pour the sodium hydroxide into the water. Stir with a long-handled, stainless steel spoon until it’s all dissolved. This is the ‘lye’ solution. Set aside.
  7. Pour the now highly caustic lye solution into the oils.
  8. Stir manually until all the fats and oils have dissolved, and then bring the soap to a medium trace using a stick blender.
  9. Now, working quickly, stir in the salt and essential oil mixture and pour into a pre-prepared mould/ moulds e.g. lined if necessary, adding bladderwrack to the base if you like. NOTE: The salt will make the soap react and trace really quickly – if you don’t move fast you could be trying to pour semi-set concrete, as I was.
  10. Cover with clingfilm and leave to set for 12 hours or so, until the soap has reached a hard cheese consistency. Leave it too long and you won’t be able to cut it. Turn out of the moulds and cut it into bars. NOTE: I used individual moulds to get around this issue. Good job, as the stuff hardened after about 30 minutes.
  11. Cure the bars for 4-6 weeks before use. This ensures that the soap has finished reacting, and no more sodium hydroxide remains in the bars. The PH of the final product should be neutral, and not at all irritating to the skin.

As indicated above, I had a few issues along the way. First, I should have cut my coconut and cocoa butter up into smaller chunks as it didn’t quite dissolve. Lumpy bits are not nice. Second, the salt made the whole thing react way too quickly and the resulting soap was un-pourable and very difficult to work with. Third, I definitely used too much kelp powder. Waaaay too much. In the words of my 2-year old daughter: “It STINKS, mummy.” Some sites suggests the pungent fishy odour will dissipiate with the curing process, leaving a more pleasant seaside aroma. Others say this is optimistic. Time will tell.

This month proved the idea that while it’s thrills we seek, it’s the spills that make life more interesting. The result was not necessarily my finest creation, but I’ve definitely learned a lot about what not to do.

photo (5)
My beautiful – stinky – bar.



2 thoughts on “Soaping up a stink”

  1. hi
    I really like your post it question is y u don’t make use of silicate in your recipe from my research I learnt that silicate is important in any soap makes soap glossy. is silicate not really necessary in soap recipe.I need more enlightenment.
    thank you

    1. Hello! Glad you found it helpful. In my limited experience there is no need to add silicate – I have made several batches of soap successfully without it – though it might be a nice extra ingredient. Best of luck with your soaping 🙂

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