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Long-lasting bar

Three hard white soap bars with crisp edges beside a sprig of lavender, a sprig of rosemary and a small block of tallow on a purple backdrop

A hard, white tallow bar built to last in a wet soap dish, with coconut oil for a quick lather, castor oil for creaminess and a pinch of salt for extra firmness. Scented with lavandin and rosemary, it is a plain, hard-wearing bar for the whole family.

Skill
Beginner
Method
Cold process
Batch
1000 g of oils about 1440 g of batter
Hands-on
1 hour
Cure
6 weeks
Gel phase
Yes insulate the mould
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What you need

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

Edible Tallow · 45.0 % 450 g 15.87 oz
Olive Oil · 25.0 % 250 g 8.82 oz
Coconut Oil · 25.0 % 250 g 8.82 oz
Castor Oil · 5.0 % 50 g 1.76 oz
Sodium hydroxide (NaOH) · the lye, 100 % pure 141.4 g 4.99 oz
Distilled water · for a 35 % lye solution 262.6 g 9.26 oz
Fine salt · 1 tsp, dissolved in the water before the lye goes in 6 g 0.21 oz
Lavandin essential oil · 2.0 % of the oils, at trace 20 g 0.71 oz
Rosemary essential oil · 1.0 % of the oils, at trace 10 g 0.35 oz
Superfat
5 %
Temperatures
Oils and lye solution each between 38 and 43 °C (100 and 110 °F)

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Method

  1. Get ready

    Put on splash goggles, nitrile gloves and long sleeves, open a window or turn on the extractor fan, and keep children and pets out of the room. Line the mould and have a towel ready to wrap it.

  2. Weigh the oils and the scent

    Weigh 450 g tallow and 250 g coconut oil into the pot, and 250 g olive oil and 50 g castor oil into a jug. Weigh 20 g lavandin and 10 g rosemary essential oil into a small glass cup.

  3. Dissolve the salt

    Weigh 262.6 g distilled water into a heat-safe jug and stir in a level teaspoon of fine salt until it has dissolved completely.

  4. Make the lye solution

    Weigh 141.4 g sodium hydroxide into a small dry container. In a well-ventilated spot, pour it slowly into the salt water, never the water onto the lye, and stir until clear. Leave it to cool, labelled and out of reach.

  5. Melt the tallow and coconut oil

    Melt the tallow and coconut oil together on low heat until completely clear, then pour in the olive and castor oils.

  6. Check the temperatures

    Carry on when both the oils and the lye solution are between 38 and 43 °C (100 and 110 °F). Much cooler and the tallow starts to cloud and set, which thickens the batter before it has traced.

  7. Combine and blend to light trace

    Pour the lye solution into the oils down the shaft of the stick blender, tap the blender to let trapped air out, then pulse and stir until a drizzle leaves a faint line on the surface. Tallow brings trace on steadily, usually within a few minutes.

  8. Add the scent

    Stir the lavandin and rosemary oils through by hand with the spatula, then give the batter one short pulse to even them out.

  9. Pour and insulate

    Pour into the mould, tap it on the worktop to raise air bubbles, and cover it with a lid or board and a folded towel for a day. Gelling the whole loaf gives an even colour and a bar that hardens sooner.

  10. Clean up with your gloves on

    Wipe the raw batter off the pot and tools with paper towels into the bin, then wash everything in hot soapy water.

  11. Unmould and cut promptly

    After 24 to 36 hours, as soon as the loaf is firm enough to unmould, take it out with gloves on and cut it into bars about 2.5 cm (1 in) thick. Tallow and salt together make a loaf that gets harder to cut cleanly with every day it waits.

  12. Cure

    Stand the bars on edge in a dry, airy room for six weeks, turning them every few days. They are usable after four, and harder and longer-lasting after six.

Tips

  • Use tallow that smells clean when melted. Any beefy smell carries into the soap, and lavandin will not fully cover it.
  • Keep the bar on a slatted dish that drains. Even a hard bar wears away fast sitting in a puddle.
  • For a softer, creamier tallow bar with less coconut oil, see Creamy tallow and olive bar; for a tallow scrub for grimy hands, see Firm scrubbing bar.

Why make it

Animal fats have been used for soap for hundreds of years, and tallow still makes one of the hardest, longest-lasting bars a home maker can. This one reads hardness 48 on our scale, with cleansing 19 and a dense, creamy lather from the tallow and castor oil, so it is mild enough for daily use on most skin. A teaspoon of salt in the lye water firms it a little more. It suits a busy family bathroom or a shower where the soap sits wet. Makers' praise for tallow soap as the bar that simply lasts rests on experience rather than measurement, though the chemistry agrees: the palmitic and stearic acids that make tallow solid also make a soap that dissolves slowly. It is not vegetarian; the variants put lard, palm oil or kokum butter in the tallow's place.

Sources

  • Pure Soapmaking, by Anne-Marie Faiola · Storey Publishing, 2016

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 12.3 %
  • Myristic acid 6.5 %
  • Palmitic acid 17.0 %
  • Stearic acid 11.7 %
  • Ricinoleic acid 4.4 %
  • Oleic acid 36.2 %
  • Linoleic acid 5.3 %
  • Other 6.1 %

Saturated : unsaturated 51 : 49

Hardness 48 29–54
Cleansing 19 12–22
Conditioning 47 44–69
Bubbly lather 23 14–46
Creamy lather 33 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

9 variations

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

From the guides

All guides
Intermediate 10 min read

Lard and tallow: soaping with animal fats

Why lard and tallow make hard, mild, creamy soap, how to render and store them at home, how beef, mutton and pork fat differ, and classic recipes.
Intermediate 19 min read

Soap additives: salt, sugar, sodium lactate, clays, oats, silk and more

What common soap additives do, how much to use and when they go in: sourced doses for sodium lactate, salt, sugar, honey, citric acid, clays, oats and silk.
Beginner 8 min read

Curing and storing handmade soap

What curing does to cold process soap and what it doesn't, how long it takes, how to set bars up to cure, how to tell when they're done, and how to store them.

Where these proportions come from

Our own construction, aimed at a bar that survives a wet soap dish: 45 % tallow for a hard, slow-wearing bar, 25 % coconut oil for a quick lather, olive and castor oil for a creamier feel, and a little less water than usual. A teaspoon of salt in the lye water, at the rate Anne-Marie Faiola gives for harder soap, firms it further.

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