Sea salt bar
A plain white salt bar: 80 % coconut oil at a 17 % superfat with fine sea salt at half the oil weight, lightly scented with lavender and eucalyptus. It sets as hard as stone and gives a low, creamy lather, and a cavity mould means no race to cut it.
- Skill
- Intermediate
- Method
- Cold process
- Batch
- 500 g of oils about 982 g of batter
- Hands-on
- 45 min
- Cure
- 6 weeks
- Gel phase
- Either way gel or not, both work
What you need
For 500 g of oils, which fills a 12-cavity silicone mould, 1.2 litres in all, with cavities of about 100 ml; the dense batter fills eight or nine. Weigh everything, liquids included.
| Coconut Oil · 80.0 % | 400 g | 14.11 oz |
| Shea Butter · 10.0 % | 50 g | 1.76 oz |
| Castor Oil · 5.0 % | 25 g | 0.88 oz |
| Olive Oil · 5.0 % | 25 g | 0.88 oz |
| Sodium hydroxide (NaOH) · the lye, 100 % pure | 71.6 g | 2.52 oz |
| Distilled water · for a 33 % lye solution | 145.3 g | 5.13 oz |
| Sea salt, fine · half the oil weight, folded in by hand | 250 g | 8.82 oz |
| Lavender essential oil · 2.0 % of the oils, at trace | 10 g | 0.35 oz |
| Eucalyptus radiata essential oil · 1.0 % of the oils, at trace | 5 g | 0.18 oz |
- Superfat
- 17 %
- Temperatures
- Oils and lye solution each at 38 to 43 °C (100 to 110 °F)
Method
-
Get ready
Put on splash goggles, gloves and long sleeves, open a window and keep children and pets out of the room. Stand the cavity mould on a tray, and weigh 250 g fine sea salt into its own bowl now: once it goes in, the batter will not wait. -
Weigh the oils and scent
Weigh 400 g coconut oil and 50 g shea butter into the pot, and 25 g olive oil and 25 g castor oil into a jug. Weigh 10 g lavender and 5 g eucalyptus radiata essential oil into a small glass. -
Make the lye solution
Weigh 145.3 g distilled water into a heatproof jug and 71.6 g sodium hydroxide into a dry container. At the open window, pour the lye slowly into the water, never the reverse, stir until clear and leave it to cool to 38 to 43 °C (100 to 110 °F). -
Melt the oils
Melt the coconut oil and shea butter until clear, then stir in the olive and castor oils. Keep them at 38 to 43 °C (100 to 110 °F): coconut oil starts to set at about 24 °C (75 °F), and warm batter stays workable longer once the salt is in. -
Blend to light trace only
Pour the lye solution into the oils and stick blend in short bursts until the batter just reaches light trace, when a drizzle leaves a faint line. Stop there; it thickens fast from here. -
Add the scent
Stir in the essential oils with a spatula. -
Fold in the salt
Tip in the salt and fold it through with the spatula, not the stick blender, until no dry salt remains. The batter turns thick and grainy, like stiff porridge. -
Fill the cavities
Spoon the batter into the cavities, press it down with the back of the spoon and tap the tray firmly on the worktop to settle it. Smooth the backs. -
Leave it uncovered
Leave the mould uncovered and uninsulated; this much coconut soap heats up well enough on its own. -
Clean up
With your gloves still on, scrape the salty batter off the pot and tools with paper towels into the bin, then wash everything in hot soapy water. -
Unmould
Turn the bars out once they are firm, anywhere from a few hours to the next day. In cavities there is nothing to cut, so there is no hurry. -
Cure
Stand the bars on a rack with air around them for at least six weeks, turning them now and then. Salt bars go on hardening for months, and many makers keep them longer.
Tips
- The quality numbers read harsh, cleansing 54, because they are worked out from the fatty acids alone and are the same at a 5 % or a 20 % superfat. The 17 % superfat is what makes this much coconut soap mild.
- Use only fine sea salt or plain table salt. Dead Sea salt and Epsom salt carry magnesium, which pulls water from the air and makes a soft, weeping bar.
- In a loaf mould, cut the loaf 2 to 4 hours after pouring, as soon as it holds a clean edge; left overnight, a salt loaf shatters under the knife.
- For a pink version with rose clay and more salt, see our pink salt spa bar. Our coconut brine bar dissolves a little salt in the water instead, for a smooth bar with more lather.
The oils
| Oil | Share |
|---|---|
| Coconut Oil | 80.0 % |
| Shea Butter | 10.0 % |
| Castor Oil | 5.0 % |
| Olive Oil (virgin / refined / olive oil) | 5.0 % |
How it is made
| Process | Cold process |
| Alkali | NaOH |
| Superfat | 17 % |
| Water | lye water at 33 % |
| Iodine value | 21 |
| INS | 221 |
Why make it
A salt bar suits anyone who wants a bar that lasts. Fine salt at half the oil weight sets it rock hard, and it washes with a low, dense, creamy lather rather than big bubbles. It is 80 % coconut oil because coconut soap is the one that still dissolves and lathers in brine, as soapmakers recorded over a century ago, and the 17 % superfat is the craft's way of keeping that much coconut soap from stripping skin. Our quality numbers, cleansing 54, cannot see the superfat. Makers often sell salt bars as spa soap, and many people love the silky feel. There is no evidence that salt in a rinse-off soap feeds the skin minerals or draws anything out of it, so the reason to make one is the bar itself. Expect it to sting on a cut or freshly shaved skin, and give it a draining dish.
Sources
- Pure Soapmaking · Anne-Marie Faiola, Storey Publishing, 2016
- The Handbook of Soap Manufacture · W. H. Simmons and H. A. Appleton, Scott, Greenwood and Son, 1908
- The Complete Photo Guide to Soap Making · David Fisher, Creative Publishing International, 2018
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 39.3 %
- Myristic acid 15.1 %
- Palmitic acid 8.2 %
- Stearic acid 6.8 %
- Ricinoleic acid 4.4 %
- Oleic acid 14.4 %
- Linoleic acid 2.9 %
- Other 11.7 %
Saturated : unsaturated 79 : 21
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
8 variationsThe same soap with one thing moved. Each opens in the calculator ready to change again.
- 15 % superfat
- 20 % superfat
- Babassu Oil instead of Coconut Oil
- Palm Kernel Oil instead of Coconut Oil
- 15 % superfat and Babassu Oil instead of Coconut Oil
- 15 % superfat and Palm Kernel Oil instead of Coconut Oil
- 20 % superfat and Babassu Oil instead of Coconut Oil
- 20 % superfat and Palm Kernel Oil instead of Coconut Oil
From the guides
All guides
Salt bars: spa soap with sea salt
Why salt bars are mostly coconut oil at a 15 to 20 % superfat, how much salt to use and which to avoid, when to cut them, and how brine bars differ.
Superfat and lye discount: why recipes leave some oil unsaponified
What superfat and lye discount mean, how the calculator applies them, where makers set them for each soap, and why oil added at trace isn't the oil left over.
Soap moulds: choosing one and sizing a recipe to fit
Silicone, wood, slab, cavity, tube and improvised soap moulds; lining with freezer paper; and how to size a recipe to a mould, with a worked example.
Where these proportions come from
The superfat is not optional here. At 5 % this is a laundry bar.
Craft convention: 70 to 100 % coconut oil with a superfat of 15 to 20 %, because salt suppresses lather and coconut soap stands up to it best, while the high superfat is what keeps that much coconut soap from stripping. Here coconut oil is 80 % at a 17 % superfat, with fine sea salt at half the oil weight, the low end of the 50 to 100 % makers use.