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Traditional

Savon noir, olive soft soap

A glass jar of glossy, translucent amber olive soft soap with a wooden spoon in it, beside a rough grey kessa mitt and a few black olives on a pink backdrop

The soft olive soap of the Moroccan hammam: olive oil cooked with potassium hydroxide into a translucent paste you scoop from a jar. Spread it on damp skin and rinse it off, following it with a rough mitt if you like, or use it as an all-round soft soap. Lightly scented with eucalyptus.

Skill
Advanced
Method
Hot process
Batch
500 g of oils about 1107 g of batter
Hands-on
1 h 15 min
Cure
None ready once cool
Gel phase
In the pot it gels as it cooks
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What you need

For 500 g of oils, which fills about 1.2 litres of lidded jars. Weigh everything, liquids included.

Olive Oil · 100.0 % 500 g 17.64 oz
Potassium hydroxide (KOH) · the lye, 90 % pure; if your label says otherwise, weigh 107.9 g at 85 % or 96.5 g at 95 % 101.9 g 3.59 oz
Distilled water · for a 17 % lye solution 500.0 g 17.64 oz
Distilled water, just boiled, for the doneness test · a small glassful, with a heaped teaspoon of paste stirred in 60 ml
Distilled water, just boiled, to soften the paste · up to this much, stirred in 20 g at a time after the cook, only if the paste is stiffer than you want 100 g 3.53 oz
Eucalyptus essential oil (globulus) · 1.0 % of the oils, after the cook 5 g 0.18 oz
Superfat
3.5 %
Temperatures
Lye solution cooled below 82 °C (180 °F), oil at 65 to 71 °C (150 to 160 °F), cooked on low

Resize or change it in the calculator

Method

  1. Get ready

    Put on sealed goggles, nitrile gloves and long sleeves, and keep them on until the soap is cooked. Weigh 500 g olive oil into a slow cooker of 3.5 litres or more, 500 g distilled water into a heat-proof jug and 101.9 g potassium hydroxide flakes into a dry container, then close the flake tub at once: it pulls water from the air.

  2. Make the lye solution

    At an open window, add the flakes to the water a little at a time, stirring, never the water to the flakes. Potassium hydroxide fizzes and gets hotter than sodium hydroxide as it dissolves; let the solution cool below 82 °C (180 °F), and keep it away from aluminium, tin and zinc, which it attacks, giving off hydrogen.

  3. Warm the oil

    Heat the olive oil in the slow cooker on low to 65 to 71 °C (150 to 160 °F).

  4. Blend to a paste

    Pour the lye solution into the oil and stick blend in bursts of a minute or two, stirring between them and resting the blender now and then so its motor does not overheat. With water equal to the oil the batter stays thin for a long time, then thickens, separates and comes back, sometimes more than once; keep going until it holds together as a thick, opaque paste, which with olive oil alone can take 30 to 45 minutes.

  5. Cover and cook

    Put the lid on and leave the cooker on low. Stir back any liquid that has separated after 15 to 20 minutes and again 15 to 20 minutes later, then stir every 30 to 45 minutes.

  6. Cook until translucent

    Over 2 to 3 hours the paste turns golden amber and translucent from the edges inwards. It is ready to test when no opaque, creamy patches come up as you fold it over.

  7. Test a spoonful in hot water

    Stir a heaped teaspoon of paste into 60 ml of just-boiled distilled water until it dissolves, and let it cool. Clear or faintly hazy means the soap is done; milky, or with an oily film on top, means another hour of cooking and a second test.

  8. Cool it a little and scent it

    Turn off the cooker and leave the soap with the lid on for about 30 minutes, until it is warm rather than hot. Stir in 5 g eucalyptus essential oil until it disappears, or leave it out for an unscented soap.

  9. Soften it if you like

    Savon noir should be a soft jelly you can scoop with a spoon. If yours is stiffer, stir in just-boiled distilled water 20 g at a time, up to 100 g, letting each addition melt in before the next; water can go in later, but it never comes out.

  10. Pot it

    Ladle the soap into clean jars while it is still warm and soft, and put the lids on once it has cooled. It sets to a soft, glossy, translucent amber jelly.

  11. Clean up with your gloves on

    Scrape the pot and tools with paper towels into the bin, then wash them in hot water. Any uncooked paste on them is still caustic.

  12. Use it the hammam way

    After a warm bath or shower, spread a teaspoon over damp skin, keeping it away from the face and eyes, and leave it for a few minutes. Rinse it off well, rubbing with a rough kessa mitt as you rinse if you like the scrub.

  13. Store it

    Keep the jars closed, somewhere cool and out of the light, and take the soap out with a clean, dry spoon rather than wet fingers so no water gets in. Use it within a year.

Tips

  • Ours comes out amber, not black: Moroccan black soap takes its dark colour from olive pomace oil or crushed black olives. For a darker paste, use olive pomace oil, which has its own entry in the calculator and takes a little less lye, so choose it there before you weigh.
  • The lye assumes potassium hydroxide flakes of 90 % purity, the usual figure on the label. If yours says otherwise, enter it in the calculator before you weigh: flakes purer than the figure used leave the paste lye-heavy.
  • In France the name also covers a household soft soap, often of linseed oil: see our linseed soft soap. For a pourable olive soap, see our liquid castile soap, the same oil and lye cooked with less water and diluted.
  • The calculator scores it 0 for cleansing, because that figure counts only lauric and myristic acids. A potash soap of olive oil still washes well and dissolves readily, even in cool water.

Why make it

Savon noir is a potash soap, so it stays a soft jelly instead of setting into a bar, and made of olive oil alone it scores 0 for cleansing and 82 for conditioning on our scale. In Morocco, tradition uses it in the hammam: spread on skin softened by steam, left for a few minutes, then rinsed and rubbed off with a rough kessa mitt, which does the scrubbing. In France the name covers a soft soap sold for the body and a runnier one for the house. Olive oil potash soap was also the textile trade's first choice for washing wool and silk, because it dissolves readily in cold water and rinses out easily. None of this rests on trials, only on long use. It is alkaline like any soap, so keep it out of the eyes and rinse it off well.

Sources

What tradition, makers' experience and research say about soaps like this, each labelled for what it is. It is not medical advice, and no soap treats a skin condition: if you have one, ask a doctor or pharmacist.

What the numbers say

  • Palmitic acid 13.8 %
  • Stearic acid 2.8 %
  • Oleic acid 69.0 %
  • Linoleic acid 12.3 %
  • Other 2.6 %

Saturated : unsaturated 17 : 83

Hardness 17 below 29–54
Cleansing 0 below 12–22
Conditioning 82 above 44–69
Bubbly lather 0 below 14–46
Creamy lather 17 16–48

Computed from the fatty acids of the fats above. The bands are what the craft has settled on, not chemistry — a bar outside one is not wrong.

Try it differently

1 variations

The same soap with one thing moved. Each opens in the calculator ready to change again.

From the guides

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Guides with this recipe

Where these proportions come from

North African black soap is olive oil, often olive pomace oil or crushed whole olives, saponified with potash, giving a soft paste rather than a bar; in France the name also covers household soft soaps. Ours is olive oil alone, cooked to a paste in a slow cooker as our liquid castile is, with water equal to the oil. The superfat is 3.5 %, raised from 0 %: the lowest, in half-point steps, at which the published saponification ranges cannot leave the paste lye-heavy (at 0 % they could by 3.3 %). A paste soap wants the worst case at 0 % rather than 1 %, because more oil clouds it. The method is ours.

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