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Double Boiler Hot Process Soapmaking Method
Back to Overview
DBHP requires a double boiler setup. This can be arranged with any two pots, one larger than the other so that the smaller will fit inside the larger, leaving some space at the bottom and at the sides of the smaller pot.
The larger pot can be any metal; for the inside pot, choose stainless steel or heat-resistant glass.
A cake cooling rack is placed on the bottom of the larger pot, to prevent the bottom of the smaller pot to be in direct contact with the heat. An empty tin, upturned and with a couple of holes punched in the bottom, or a rag, folded several times, can be used instead of the cake rack.
How To Proceed
- Prepare your double boiler, organise your workspace and have recipe, ingredients, tools and vinegar ready.
- Measure out (by weight) water and caustic soda, then prepare the lye solution and place it in the sink to cool down.
- Measure out fats and oils (by weight), and place them in the inside pot (referred to as "soap pot" from now on). If you wish to add some oils at the end of a cook, measure these out into a separate container.
- Place the rack, tin or rags on the bottom of the large container (referred to as "boiler" from now on).
- Add to the boiler enough water for the soap pot to be half-submerged, but still not floating.
- Place the soap pot inside the boiler and turn the heat on to medium.
- When the solid fats are melted, remove the soap pot, place it on your work bench and add the lye solution as described for Cold Process soap. Leave the boiler on the stove while you do this.
- At trace, place the soap pot into the boiler and replace both lids.
- When the water in the boiler starts boiling, turn the heat down and keep to a slow simmer (lids always on) for an hour.
- While the soap cooks, prepare your moulds and the ingredients you wish to add at the end of the cook. Remember you'll have to work quickly with the cooked soap paste!
- When the soap has simmered for an hour, remove the lids and give the soap paste a stir. The soap should have a jelly-like look, with a consistency similar to applesauce and a nice golden-yellow colour. Take a small amount of soap out of the pot and place it on a saucer for the "ball test". Replace the lids.
- When the small amount of soap you have placed on the saucer has cooled down a bit, roll it between your fingers into a ball. If the ball keeps its shape, without being too sticky, and turns an opaque whitish colour, then the soap is cooked.
- Depending on batch size and base oils/fats, Double Boiler soap needs cooking for 1 to 2 hours, with shorter times for smaller batches and recipes with a higher content of saturated fats, and 2 hours for larger batches and recipes containing high amounts of insaturated fats. DBHP castile soap (olive oil only, or olive and castor oil) usually requires 2 hour cooking times.
- If the soap ball is sticky and doesn't roll between your fingers, the soap needs cooking longer. Test it again after another 15 minutes.
- If the soap ball is crumbly, the soap has been either cooked too long, or the heat was too high during the cook, or maybe you have forgotten to replace the lids at some stage. The soap is going to be perfectly usable, but you might find it difficult to mould.
- Remember that the water in the boiler must simmer, and never boil too fast.
- When the soap paste is ready, turn the heat off and let the water in the boiler cool down to 50 to 60ºC (122 to 140ºF). You can now add the extra ingredients.
- If you keep the soap pot inside the boiler, the soap paste will remain soft longer, and adding the extra ingredients will be easier. Be extra careful when mixing, to avoid hot water splashes!
- When all the ingredients have been added and stirred in thoroughly, pour or scoop the soap into the prepared mould(s). Tap each mould to get rid of air pockets and ensure proper filling. Larger moulds might need "banging" on the work bench, and you might want to place a couple of rags between mould and bench to avoid damages.
- Place a piece of baking paper on the soap and press/smooth down with a clean spoon (or you can use your hands, if you are wearing rubber gloves).
- To obtain a smoother, finer looking soap, you can insulate the moulds as explained for Cold Process soap. The soap paste will cool down slowlier, and will settle down better in the mould.
- When the soap has cooled down, you can cut it or slice it before arranging on racks for the 4 weeks curing period. You can however test your soap straight away, because cooking insures that saponification is complete at the end of the cook.
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