Shaving croap

Method

1. Get ready

   Put on splash goggles, gloves and long sleeves, and keep them on until the croap is in its tubs. Weigh 250 g stearic acid, 100 g coconut oil and 75 g shea butter into a slow cooker, 50 g castor oil and 25 g olive oil into a jug, 250 g distilled water into a heat-proof jug, and 28.8 g sodium hydroxide and 67.4 g potassium hydroxide flakes into two dry containers; close the flake tub at once.

2. Make the lye solution

   At an open window, stir the sodium hydroxide and then the potassium hydroxide into the water a little at a time, always lye into water. Potassium hydroxide fizzes loudly and the solution gets very hot; keep it away from aluminium and let it cool below 82 °C (180 °F) while you melt the fats.

3. Melt the fats hot

   Melt the stearic acid, coconut oil and shea butter in the slow cooker on high, stir in the castor and olive oils, and turn the cooker to low. Half of this fat is stearic acid, which sets at about 55 °C (131 °F), so hold the blend above 60 °C (140 °F).

4. Pour in the lye

   Pour the lye solution into the fats in one steady stream, stirring hard with a sturdy spatula. The batter turns milky and thickens to a paste almost at once as the stearic acid becomes soap.

5. Work it smooth

   Break the paste up with short bursts of the stick blender and the spatula until it is even and no liquid lye pools in the pot. With more water and more potassium than a puck, it stays softer and stickier, like thick, heavy cream cheese.

6. Cook it through

   Cover and cook on low for about an hour, folding it over every 15 to 20 minutes and scraping the edges back into the middle, and stirring it down if it puffs up.

7. Check it is done

   It is ready when it is glossy and translucent right through, like petroleum jelly, with no opaque white streaks when you fold it. If you have phenolphthalein, a drop on a smear should turn only a faint, slow pink; a vivid magenta at once means another 20 to 30 minutes.

8. Stir in the glycerin

   Turn off the cooker and stir the 30 g of glycerin through the hot soap until it disappears. It loosens the croap a little, which makes the tubs easier to fill.

9. Fill the tubs

   Spoon the hot croap into four wide tubs, pressing each spoonful down to push out air and tapping the tub on the bench, and smooth the tops with the back of a spoon.

10. Let it firm

    Leave the tubs open somewhere airy for four weeks, then put the lids on. It firms to a dense, soft soap that holds its shape but takes the print of a fingernail, and it loses a little water and weight as it goes.

11. Load the brush

    To use it, wet the brush, shake it out and swirl it on the croap for ten seconds or so; it loads far faster than a hard puck. Build the lather in a bowl or on your face, adding water a few drops at a time.