Indigo and annatto funnel pour bar

Method

1. Plan the two batches

   This is one recipe made as two batches a day or two apart. Three quarters of every amount makes the dark base, poured round five pipes; the last quarter fills the holes they leave. The weighing list's 138.4 g of sodium hydroxide and 302.9 g of water are the totals for both, so work out three quarters and a quarter of each and write the four figures down.

2. Infuse the annatto ahead

   A day or more before, put the teaspoon of annatto seeds in a small jar with 30 g of canola oil, extra to the recipe's. Stand the jar in a pan of hot water on the lowest heat for 4 hours with a thermometer in the oil, holding it at about 49 °C (120 °F): above about 54 °C (130 °F) the seeds scorch. Never heat it over a direct flame or leave it unattended, and strain it through fine cloth.

3. Set the pipes in the mould

   Rub five 10 cm lengths of 1-inch PVC pipe, about 3.3 cm across the outside, with a thin film of mineral oil, which never turns to soap, and wipe off the excess. Stand them upright in a row down the middle of the lined mould, 5 cm apart and the end ones 2.5 cm from the ends, and hold each to the floor with a rubber band stretched under the mould and over its top, so no batter creeps underneath. Set the mould level on a heating pad, switched off, where it can stay for the next few days.

4. Make batch one's lye solution

   Put on goggles, gloves and long sleeves and open a window. Weigh three quarters of the sodium hydroxide and of the water, pour the lye slowly into the water, never the reverse, and stir until clear. Stir the tablespoon of indigo in gently until no dry lumps are left, then 1½ teaspoons of the sodium lactate, and leave it labelled and out of reach.

5. Weigh and warm batch one's oils

   Weigh 187.5 g canola oil, 187.5 g rice bran oil, 187.5 g coconut oil, 112.5 g shea butter and 75 g avocado oil. Take 32 g of the canola: stir the alkanet into 25 g of it in a cup and the ½ teaspoon of titanium dioxide into the other 7 g in a spouted jug. Melt the coconut oil and shea butter, add the rest of the liquid oils, and bring both the oils and the lye solution to 49 to 54 °C (120 to 130 °F): the base has to start warm to gel hot.

6. Blend to light trace

   Stir the lye solution to lift the indigo that has settled, pour it in down the blender shaft, tap out trapped air, and blend in short pulses to light trace, thin custard that holds a faint line for a few seconds. Stir in 12 g of the lemongrass oil and 6 g of the rosemary oil.

7. Split the base

   Pour 250 g of batter into the titanium dioxide jug and whisk it to a pale blue-grey. Whisk the alkanet into the batter left in the pot, about 830 g, until it is evenly dark.

8. Spiral the pale into the dark

   Hold the pale jug about 15 cm (6 in) above the pot and pour all of it into the dark batter in a spiral, from the edge towards the middle. Don't stir.

9. Pour round the pipes

   Pour the batter into one corner of the mould and let it find its own way round the pipes, drawing the pale streaks with it; tap the mould gently if it heaps up instead of flowing. It should stand about 6 cm deep.

10. Gel it hot

    Cover the mould with a board and a towel and switch the heating pad to medium for 30 minutes, looking every 10: a crack, bubbling or a rising middle means it is too hot, so switch off and uncover it. Then switch the pad off and leave the mould covered on it for 24 hours. Indigo needs the heat of a full gel to come out blue; without it, it stays greyer.

11. Pull the pipes

    After 24 hours, take off the bands and pull each pipe straight up, slowly and without twisting, pressing the soap down beside it with your other hand. If one will not come, leave it another day. Keep the base in the mould and fill it within a day or two, while it is fresh enough to bond.

12. Weigh batch two

    Weigh the last quarter: 52.5 g canola oil, 62.5 g rice bran oil, 62.5 g coconut oil, 37.5 g shea butter and 25 g avocado oil, with 10 g of the annatto oil standing in for the rest of the canola. Put that 10 g in one jug; from the canola, stir the ¼ teaspoon of titanium dioxide into 10 g in a second jug and the charcoal into 10 g in a third.

13. Make batch two

    With goggles and gloves on again, make the lye solution with the last quarter of the sodium hydroxide and water as before, stir in the last ½ teaspoon of sodium lactate, and let it cool to 41 to 43 °C (105 to 110 °F). Melt the coconut oil and shea butter, add the rest of the liquid oils, and bring them to the same temperature.

14. Blend and colour

    Blend to light trace, stir in the last 4 g of lemongrass and 2 g of rosemary oil, and pour a third, about 113 g, into each jug. Whisk each one smooth, white, orange or black, and keep them thin: this pour needs batter that runs.

15. Funnel-pour the holes

    Hold the white jug about 15 cm (6 in) above the first hole and pour a thin, steady stream into it for a count of three, then do the same over each hole. Pour the orange into the middle of each white from the same height, so it breaks through, then the black into the middle of the orange.

16. Repeat until full

    Keep going round, white, orange, black, until the holes are full to the top of the base, and pour anything left into a small mould the same way. Mist the top with alcohol, away from any flame, and leave the mould for 2 days.

17. Cut through the rings

    Unmould with gloves on and cut the loaf across into five blocks about 5 cm wide, each with a circle in its middle. Lay each block on its side and cut it in half parallel to the top, so every bar shows a target of white, orange and black rings on its cut face.

18. Cure

    Stand the bars with air between them, out of direct sun, for 6 weeks, turning them every few days.