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Everyday bars

Seaweed and sea salt bar

Three muted sea green soap bars with fine dark flecks beside dishes of kelp powder and fine sea salt on a purple backdrop

An everyday bar coloured a muted sea green with kelp and spirulina, with a little fine sea salt stirred in at trace for a firmer bar. Lavender, eucalyptus and cedarwood give it a fresh scent, and with only a little salt it lathers far more freely than a salt bar.

Skill
Beginner
Method
Cold process
Batch
1000 g of oils about 1492 g of batter
Hands-on
1 h 10 min
Cure
4 weeks
Gel phase
No keep it cool
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What you need

For 1000 g of oils, which fills a 1.5 litre loaf mould. Weigh everything, liquids included.

Olive Oil · 40.0 % 400 g 14.11 oz
Coconut Oil · 30.0 % 300 g 10.58 oz
Shea Butter · 15.0 % 150 g 5.29 oz
Rice Bran Oil · 10.0 % 100 g 3.53 oz
Castor Oil · 5.0 % 50 g 1.76 oz
Sodium hydroxide (NaOH) · the lye, 100 % pure 139.6 g 4.92 oz
Distilled water · for a 33 % lye solution 283.4 g 10.00 oz
Kelp powder · about 1 tbsp, finely ground, stirred with the spirulina into 2 tbsp of the recipe's olive oil 8 g 0.28 oz
Spirulina powder · 2 tsp, stirred into the olive oil with the kelp 4.7 g 0.16 oz
Sea salt, fine · 2 tbsp, stirred into the batter at trace, not dissolved in the lye water 32 g 1.11 oz
Lavender essential oil · 1.5 % of the oils, at trace 15 g 0.53 oz
Eucalyptus radiata essential oil · 0.5 % of the oils, at trace 5 g 0.18 oz
Atlas cedarwood essential oil · 0.5 % of the oils, at trace 5 g 0.18 oz
Superfat
6 %
Temperatures
Oils and lye solution each at 35 to 40 °C (95 to 104 °F)

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Method

  1. Get ready

    Open a window, put on splash goggles, nitrile gloves and long sleeves, and line or set out a 1.5 litre loaf mould. Wear a dust mask while you measure the kelp and spirulina powders.

  2. Weigh everything

    Weigh 300 g coconut oil and 150 g shea butter into the pot, and 400 g olive oil, 100 g rice bran oil and 50 g castor oil into a jug. Weigh 31.6 g (2 tbsp) fine sea salt into a small bowl and 15 g lavender, 5 g eucalyptus and 5 g Atlas cedarwood essential oil into a small glass.

  3. Make the lye solution

    Weigh 283.4 g distilled water into the lye jug and 139.6 g sodium hydroxide into a dry container. At an open window or under the extractor fan, pour the lye slowly into the water, never the reverse, stir until clear and leave it to cool, labelled and out of reach; the salt does not go in here.

  4. Disperse the seaweeds

    Stir 8 g (about 1 tbsp) kelp powder and 2 tsp (4.7 g) spirulina into 2 tbsp (about 27 g) of the olive oil from the jug until no dry specks remain.

  5. Melt the fats

    Melt the coconut oil and shea butter on the lowest heat, then pour in the rest of the olive oil and the rice bran and castor oils. Let the oils and the lye solution each come to 35 to 40 °C (95 to 104 °F).

  6. Blend to light trace

    Pour the lye solution into the oils down the shaft of the stick blender, then pulse for a few seconds at a time, stirring between pulses. Stop at light trace, when the batter looks like thin custard and a drizzle leaves a faint line that sinks back within seconds.

  7. Add the colour and scent

    Whisk in the seaweed oil, then the essential oils, and give a few short pulses until the batter is an even green with fine darker flecks.

  8. Stir in the salt

    Stir in the 31.6 g of sea salt by hand with the spatula until it is evenly spread. The batter thickens slightly as it goes in.

  9. Pour and keep cool

    Pour into the mould, tap it on the worktop and smooth the top. Lay a sheet of baking paper over it but no towel, and leave it in a cool room: heat dulls spirulina's green.

  10. Clean up

    With your gloves still on, wipe the batter off the pot and tools with paper towels into the bin, then wash everything in hot soapy water.

  11. Unmould and cut

    After 24 to 36 hours, when the loaf is firm, put your gloves back on, unmould it and cut it into bars about 2.5 cm (1 in) thick. The salt makes it set sooner and harden faster, so don't leave it for days before cutting.

  12. Cure

    Stand the bars on edge on a rack with air around them, out of the sun, for four to six weeks, turning them every few days.

Tips

  • The green starts bright and settles to a softer sea green within a week or two as the spirulina fades; kelp holds its browner olive. Cure and store the bars out of direct light.
  • The salt goes in at trace, not into the lye water: a lye solution holds very little salt, and the rest would come back out as grit.
  • Don't simply add more salt. Salt cuts lather, and an ordinary bar loses more of it the more you add; a salt bar needs mostly coconut oil and a high superfat, as in our pink salt spa bar.
  • Buy finely ground, food-grade kelp powder; coarse flakes feel scratchy in the bar.

Why make it

An everyday bar with a seaside theme, cleansing 20 and conditioning 56 on our scale, with a little more coconut oil than usual so it still lathers freely around the salt. The salt, about 3 % of the oils, gives a firmer, longer-lasting bar while stopping far short of a salt bar, which trades lather for hardness. Seaweed bathing has a long history on Ireland's Atlantic coast, where hot seaweed baths were a Victorian craze and a few bathhouses still run (Tourism Ireland). In this bar, kelp and spirulina are colour and fine flecks; any benefit people hope for from seaweed rests on that tradition rather than on evidence about a rinse-off soap. The green softens to a muted sea green within weeks, and lavender, eucalyptus and cedarwood give it a fresh scent.

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

  • Lauric acid 14.8 %
  • Myristic acid 5.7 %
  • Palmitic acid 10.6 %
  • Stearic acid 8.6 %
  • Ricinoleic acid 4.4 %
  • Oleic acid 41.5 %
  • Linoleic acid 9.7 %
  • Other 5.7 %

Saturated : unsaturated 44 : 56

Hardness 40 29–54
Cleansing 20 12–22
Conditioning 56 44–69
Bubbly lather 25 14–46
Creamy lather 24 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.

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Where these proportions come from

Our own formulation: olive oil with 30 % coconut oil, shea butter, rice bran oil and a little castor oil at a 6 % superfat. Coconut sits a little higher than in an everyday bar because salt cuts lather and coconut soap stands up to it best; at about 3 % of the oils, the salt firms the bar without turning it into a salt bar.

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