Scent Almanac
Salt bar (spa bar)
A hard, luxurious spa bar packed with fine salt. High coconut oil gives lather through the salt, and a 20% superfat keeps it mild.
- Difficulty
- ●●●
- Time
- active 1.5 h · cut in 1–3 h · cure 6–8 weeks
Safety first
- Wear chemical-splash goggles (not just glasses), nitrile or rubber gloves, long sleeves and closed shoes from the moment the lye container opens until the raw soap is put away.
- Mix lye solution in a well-ventilated spot: under a running range hood, by an open window, or outdoors. Don't lean over it. The fumes in the first minute sting the lungs.
- Always add lye to water, never water to lye ('snow falls on the lake'). Pouring water onto lye can erupt and splash boiling caustic liquid.
- Mix and hold lye in a heavy stainless steel or #5 PP plastic container, and stir with stainless or silicone. NEVER use aluminum, which reacts violently and gives off hydrogen gas. Avoid glass, which lye etches and can crack.
- Keep children and pets out of the room until the lye, raw soap and all tools are cleaned up and put away.
- Keep vinegar handy for wiping lye or raw soap off counters and floors. It is for surfaces only. For skin and eyes, use plain running water: flush for 15 minutes. For eyes, flush for 15 minutes and get medical help.
- Weigh everything (oils, water and lye) on a digital scale in grams. Never measure by volume.
- Run every recipe through a lye calculator before you make it, including this one and any time you swap an oil. The preset here opens in the app's lye calculator.
- Store lye sealed, labeled and out of reach. Raw soap stays caustic for a day or two, so wear gloves to unmold and cut it.
- Salt bars harden fast and can become rock-hard within hours. Plan to cut a loaf early, or use individual molds, so you're not forcing a knife through it.
Steps
- Check the recipe in the lye calculator and write down the weights, including the salt. Put on protective gear and clear the room.
- In a ventilated spot, add the lye to the water (never water to lye) in a stainless steel or #5 PP container, stir until clear, and let it cool to about 100°F (38°C).
- Melt the coconut oil and shea butter, then add the olive and castor oils. Cool to about 100°F (38°C).
- Weigh the fine salt into a separate container so it's ready. You'll have to work fast once it goes in.
- Pour the lye solution into the oils and stick-blend to light trace. High-coconut batter traces quickly.
- Stir in the fragrance, then fold in the salt with a spatula until evenly mixed. The batter thickens noticeably.
- Spoon or pour into individual molds, or a loaf mold, and tap firmly to settle.
- Don't insulate. High-coconut bars heat up and gel on their own, and too much heat can crack them. If you see cracks forming, move the mold to the fridge.
- Unmold and cut early: a loaf needs cutting within 1–3 hours, as soon as it holds its shape, or it becomes too hard and crumbles. Individual bars can come out after 4–12 hours.
- Cure on a rack for at least 6–8 weeks. Salt bars get milder and harder the longer they cure.
- Before use, do the zap test or check with a pH strip (9–10 is normal).
NaOH138.2 g · 4.9 oz
Water (distilled)281 g · 9.9 oz
2.0 : 1 water to lye
Fragrance30 g · 1.1 oz
Batch weight1449 g · 51.1 oz
| Oil | % | Weight |
|---|---|---|
| Coconut oil (76°) | 80.0 | 800 g · 28.2 oz |
| Olive oil | 10.0 | 100 g · 3.5 oz |
| Shea butter | 5.0 | 50 g · 1.8 oz |
| Castor oil | 5.0 | 50 g · 1.8 oz |
Bar qualities
Hardness
67
Cleansing
54
Conditioning
24
Bubbly
58
Creamy
18
Iodine
24
INS
219
Green bands are the usual ranges for a balanced bar. Liquid soap, castile and salt bars fall outside them on purpose.
Lye safety: wear goggles and gloves. Add lye to water, never water to lye, in a heat-safe stainless or #5 plastic container, with good ventilation and no children or pets nearby. Always double-check a lye amount with a second calculator before you make soap.
If something goes wrong
- Loaf crumbles or cracks when cut
- It was cut too late. Cut within 1–3 hours, or switch to individual molds.
- Bars weep or sweat beads of water
- Dead Sea or Epsom salt pulls moisture from the air. Use plain fine sea salt.
- Batter seized before the salt went in
- The oils were too warm, or the fragrance accelerated it. Soap at about 100°F (38°C), and have the salt weighed and ready.
- Scratchy bar
- The salt was too coarse. Use fine-grain sea salt.
- Soda ash (white powdery film on top)
- Harmless: unreacted lye met air before saponification finished. Steam it off, plane it off, or wash the bar once. Prevent it by spritzing the fresh top with 91–99% isopropyl alcohol, covering the mold, and using a higher lye concentration.