The craft of making Cold-process Soap – swirling the Mantra
Cold process soap is made from the chemical reaction between acids (from oils and butters) and an alkali (in the case of cold process soap, this is sodium hydroxide).
The result is an alkaline salt of the oils and butters used. All naturally-made soaps are alkaline, indeed a true soap cannot be anything but alkaline due to its chemical composition.
The so-called ‘pH neutral soaps’, proclaimed so loudly by various skin care companies, are actually a mixture of different synthetic detergents and bear no relation whatsoever to the beautifully natural, gentle, glycerine-rich soaps produced by the cold process method.
So how is cold process soap made? I’ll take you through the method and use some images of a ‘Water’ mantra swirl to show you.
Firstly, the lye solution must be made up: this involves dissolving sodium hydroxide in water. The reaction is strongly exothermic and so the lye solution heats up very rapidly! We use raw tussah silk (cruelty-free silk) in many of our soaps, adding it at this stage; the heat helps the alkali to hydrolyse the silk fibres.
While the lye solution is cooling, the oils and butters are weighed out, the latter being melted gently. When the lye is at the correct temperature (we always soap at room temperature), the lye solution is added to the oils & butters. The mixture is blended until it thickens to a point known as ‘trace’. The degree of thickening is controlled by the soap maker, different designs requiring different degrees of trace to work (a peacock swirl demands the lightest of trace, whereas a layered design requires something thicker).
Once trace is reached, we add our nutrient oil (a special oil, such as rosehip, argan, Monoi de Tahiti etc) and essential oils. If using colour, it is at this point that we will divide the batter up into batches to colour individually with botanical or mineral colours and clays.
The lye solution can also be made all, or in part, with animal or plant milks, beer, wine, aloe vera etc. We often use milks in my soaps for their gentleness and skin-loving properties. Milk powders may be added to the oil/butter mix and fruit / vegetable purees, honey, various botanicals, activated charcoal etc may be added at trace.
The batter is poured into the mould, either a loaf mould, or a slab mould, according to the design being created.
This is ‘Water’ mantra:
Here, the batter has been divided into three batches: two were coloured with either blue ultramarine or green chromium hydroxide; the third was left uncoloured.
Two dividers were laid along the length of the mould and the batter poured between them to create the three coloured areas seen. Once the batter is all poured, the dividers are gently removed.
Now comes the fun part – swirling! A chopstick is moved through the soap from one long side of the mould to the other, from one end to the other, turning a hairpin bend at either side. The colours are swirled together giving a classic ‘mantra’ style pattern throughout the entire soap.
Now comes the hardest part for any soapmaker – patience!
The batter needs to set up and saponify for at least 24 hours before being unmoulded, even longer depending on the recipe used. Many soapmakers wrap their soap in towels, causing it to heat up and enter the ‘gel’ phase, or even put it into a warm oven. We prefer to keep ours cool, preventing ‘gel’, to help retain the more fragile nutrient and essential oils that we use.
Once firming time has passed, the soap can be removed from the mould and cut into bars. The design on this mantra goes right through the log, as you can see:
To reveal the mantra swirl, this soap is cut horizontally as well as vertically.
The soap cut into bars and with a section of log still uncut – ‘Water Mantra’:
Once cut, the soap must be allowed to ‘cure’ for a minimum period of time. During the first 24-48 hours, the saponification process is completed; after this, the remainder of the cure time is to allow water to evaporate and the bars to harden sufficiently for use. Generally, the less water used in the recipe, the shorter the cure time. As we use a lower percentage of water compared to many soap makers, our soaps are usually ready after a cure time of about 4 weeks from cutting. The exceptions to this are our Castille (100% olive oil) and Castillor soap (olive oil with just a tiny dash of castor oil); like a fine wine, they improve with age and we cure these for a minimum of 9 months to a year before selling.
As mentioned above, the two main types of mould are the log/loaf mould and the slab mould. We now use fabulous moulds produced by ‘The Moulds Shop’ as the soap behaves so beautifully. Here you see an example of both types of mould: a slab mould (with ‘Bergander Peacock’) and a two loaf moulds (with ‘Avocado Citrus’). Both moulds have silicone liners which ensure easy removal of the set soap and clear, smooth edges (and no need to line the mould!)
Want to see how Stonesfield Soaps are made in videos? Click Here.