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Household bars

Tallow and coconut laundry bar

Three off-white tallow and coconut laundry bars, one half grated, beside a jar of soap flakes and a dish of white tallow on an indigo backdrop

A hard, plain laundry bar of half tallow and half coconut oil, made with no superfat so that no free oil goes into the wash. Rub it on stains, or grate it with washing soda into a laundry powder. Unscented, and never for skin.

Skill
Beginner
Method
Cold process
Batch
1000 g of oils about 1461 g of batter
Hands-on
45 min
Cure
4 weeks
Gel phase
Either way gel or not, both work
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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 · 50.0 % 500 g 17.64 oz
Coconut Oil · 50.0 % 500 g 17.64 oz
Sodium hydroxide (NaOH) · the lye, 100 % pure 161.3 g 5.69 oz
Distilled water · for a 35 % lye solution 299.5 g 10.57 oz
Superfat
0 %
Temperatures
Fats and lye solution at 38 to 43 °C (100 to 110 °F), left uncovered

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Method

  1. Get ready

    Put on goggles, gloves and long sleeves, open a window and set out a 1.5 litre loaf mould, lined if it needs it. Keep children and pets out of the room.

  2. Weigh everything

    Weigh 500 g tallow and 500 g coconut oil into the pot, 299.5 g distilled water into a heat-safe lye jug and 161.3 g sodium hydroxide into a small, dry container.

  3. Make the lye solution

    Pour the sodium hydroxide slowly into the water, never the water onto the lye, and stir until it runs clear, keeping your face away from the vapour. Leave it to cool to 38 to 43 °C (100 to 110 °F), labelled and out of reach.

  4. Melt the fats

    Melt the tallow and coconut oil together on low heat until completely clear, then let them cool to 38 to 43 °C (100 to 110 °F). Tallow starts to set not far below that, so don't let the fats get much cooler or the batter will stiffen before it has really traced.

  5. Blend to light trace

    Pour the lye solution into the fats down the shaft of the stick blender and blend in short pulses, stirring between them. Tallow and coconut oil trace quickly, so stop at light trace, when a drizzle leaves a faint line on the surface.

  6. Pour and leave it uncovered

    Pour into the mould and tap it on the worktop to let air bubbles rise. Leave it uncovered in a cool room: a batch this rich in coconut oil heats up on its own and can crack if you wrap it in a towel.

  7. 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.

  8. Unmould and cut within a day

    With gloves on, unmould and cut the loaf as soon as it holds a clean edge, usually 12 to 24 hours after pouring. Left for days, it turns hard and brittle and cuts with chips.

  9. Label it and keep it apart

    Label the bars as laundry soap and store them away from your bathroom soap, so no one takes them for hand soap. Handle the fresh bars with gloves.

  10. Cure for four to six weeks

    Stand the bars on a rack with air around them for four to six weeks, turning them now and then. A dry bar lasts longer as a stain bar and grates to a finer powder.

  11. Use it on stains

    Wet the stain, rub the bar into it, leave it for half an hour, then wash as usual.

  12. Make laundry powder

    Grate one cured bar on the finest holes of a grater, somewhere the dust will not blow about, and stir it into 1 cup of washing soda (sodium carbonate) in a lidded, labelled jar. Wear gloves and goggles while you mix: washing soda causes serious eye irritation, and the jar belongs out of children's reach.

  13. Dose it

    Use 2 tablespoons for a front-loading machine and up to half a cup for a top-loader, dissolved first in a cup or two of hot water, and adjust for your water and the load. A homemade powder has no HE rating, so check your machine's manual before using it in a high-efficiency washer.

Tips

  • This is the one soap where a superfat above about 1 % is a fault rather than a choice. At 0 % the calculator's range check puts the bar anywhere from about 3 % oil-rich to about 3 % lye-heavy, depending on where your tallow and coconut oil sit in their published ranges. In a wash that washing soda has already made strongly alkaline that hardly matters; on skin it does, so this bar never doubles as hand soap.
  • Tallow makes this bar harder and slower to wear away than our all-coconut laundry bar, which suits a stain bar that sits by the sink. If you avoid animal fats, make the coconut laundry bar instead.
  • Use clean, well-rendered tallow that smells of very little. Fat that smells of beef makes a bar that smells of beef, and the smell carries into the laundry basket.
  • Soda crystals, as sold in the UK, are hydrated sodium carbonate and only 37 % carbonate by weight, so it takes about 2.7 times the weight of crystals to do the work of washing soda. Wash wool and silk in a mild, neutral detergent, not in soap and soda.

Why make it

This is a bar for the wash, not for skin. Half tallow and half coconut oil with no superfat makes a very hard bar, hardness 66 on our scale, that cleans hard (cleansing 36) and leaves no free oil in the fabric. It is an old pairing: Simmons and Appleton, writing for soap factories in 1908, describe household washer soap made from tallow, which gives firmness and durability, with coconut and cottonseed oils for a quicker lather. Makers keep one by the sink as a stain bar and grate it with washing soda into laundry powder. In hard water part of any soap is lost to scum, so expect to use more (USGS), and wash wool and silk in a mild, neutral detergent instead (Woolmark). Keep it out of the bathroom: at 0 % superfat it may carry a trace of free alkali.

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 24.6 %
  • Myristic acid 11.5 %
  • Palmitic acid 16.9 %
  • Stearic acid 12.8 %
  • Oleic acid 22.5 %
  • Linoleic acid 2.6 %
  • Other 9.2 %

Saturated : unsaturated 73 : 27

Hardness 66 above 29–54
Cleansing 36 above 12–22
Conditioning 26 below 44–69
Bubbly lather 36 14–46
Creamy lather 30 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

8 variations

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

From the guides

All guides
Beginner 9 min read

Laundry soap bars and household soap

Why laundry and kitchen bars are high in coconut and made with almost no superfat, how to grate one into laundry powder, and what washing soda and borax do.
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 11 min read

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.

Guides with this recipe

Where these proportions come from

Craft convention: a laundry bar is made at zero superfat, because free oil is what leaves a residue on fabric, and tallow and coconut oil are the fats the soap trade built household soap on (Simmons and Appleton, 1908), tallow for a hard, lasting bar and coconut oil for lather. The laundry powder follows Letcavage and Harden's grated-bar method with the borax left out, as our laundry soap guide explains.

Formulation adapted from Natural Soap Making by Elizabeth Letcavage and Melissa Harden (Stackpole Books, 2013). The method and notes are ours.

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