Soap may be a mundane and everyday item, but the process of making it is a chemistry lesson in and of itself.
Soap is a salt, or a compound formed by the reaction of an acid and an alkali. In soap-making, oil (fatty acid) provides one half of the reaction, and lye (a strong alkali) does the rest. The reaction between oil and lye is known as saponification, from sapo, the Latin for soap. There are many different oils used in soap-making, each with their own set of properties. Hemp oil is known for being intensively moisturizing, as well as having protective and regenerative properties.
Techniques for making homemade soap
There are various ways to make soap at home: the most common procedures are the cold process and the melt-and-pour method. Of the two, melt-and-pour is by far the simpler, as it involves using pre-bought soaps which are melted down, mixed with new oils and scents, and then poured into new molds to set once more.
However, pre-made hemp soaps are still hard to find, despite the proliferation of hemp skincare products in recent years. Therefore, methods which allow more flexibility with the choice of ingredients are more suited to making hemp soap, and this is where the cold process comes into its own.
Care must be taken to ensure safety at all times
It is important to note that when following this recipe, some highly dangerous chemicals are needed, most notably lye (also known as caustic soda). It is vital that correct safety precautions are carried out, including use of gloves, goggles and long-sleeved clothing to avoid alkali burns. The work area must be clean and dry, and the equipment used must be made from ceramic, steel, or good-quality, heat-resistant plastic. All dangerous chemicals must be clearly labelled, and stored safely when not in use. Most of the necessary equipment can be found in the home or from the hardware store.
- Gloves, rubber or similar
- Safety goggles
- Kitchen scale (must be accurate)
- Stove or other heat source
- Large, non-stick cooking pot
- 2/3 litre jug, pitcher or mixing bowl (x2)
- 2/3 litre pitcher or beaker with tight-fitting lid
- Long-handled spoon for stirring
- Soap mould
- Electric blender (handheld/stick)
- Measuring spoons/cups
- Small dishes or tubs to store ingredients
- Whisks, spoons, spatulas, cloths, napkins
Always use stainless steel, ceramic or heat-resistant plastic for mixing chemicals. Once all equipment is checked and ready, and the work-space is clear, it is safe to begin working with the ingredients. Although known as the “cold” process, some stages of the recipe require use of a heat source, so the kitchen is the obvious location. This is what you will need:
- Lye – NaOH (caustic soda) or KOH (potash – more commonly used for soft or liquid soaps)
- Water (distilled is preferred)
- Oils/fats (see below for more info)
- Fragrances/essential oils
- Dye, natural or synthetic
Oil combinations and ratios
The choice of oil is the key to making a good-quality soap. Hard fats like tallow or palm oil provide a stable, long-lasting base for the soap, ensuring it sets correctly. Oils like castor or coconut oil are essential for lathering, and olive, sunflower and canola oil provide a softening and moisturizing effect. A fourth category of oils is informally known among soap-makers as super-moisturizing, or simply “luxury”. Hemp oil sits comfortably in this fourth category, due to its intensively softening and uniquely penetrative properties.
It is possible to make soap from just one or two oils, but experimenting with different ratios for various purposes is immensely rewarding. A ratio of 30% hard, 25% lathering, 35% moisturizing and 10% super-moisturizing oil is widely thought to be a sensible basis for a good-quality soap, although these percentages can be tweaked in numerous ways.
It is usually preferable to limit a heavy oil such as hemp to no more than 15%, due to the risk of greasiness and more rapid spoilage, although some recipes can work well with slightly higher ratios. An excellent resource on the properties of soap-making oils can be found here.
Determining the oil:lye ratio
Now that the work-space, equipment, and ingredients are ready, a recipe must be decided on, and the lye solution must be made and left to cool. The process for making lye-water is simple, yet care must be exercised. Simply stir the lye into boiling water until fully dissolved, then leave aside to cool.
The required amount depends on the combination of oils, and can be determined by using an online lye calculator – or for the arithmetically-inclined, Miller’s Homemade Soap Pages provide full saponification charts.
For beginners, there are plenty of soap recipes available online that can be tweaked to your requirements – this is sensible, as determining the lye/water ratio is difficult for those with little experience. Below is a standardized, basic recipe that will take very little skill or effort to follow:
SIMPLE SOAP RECIPE
- 900g/32oz Palm Oil (34%)
- 765g/27oz Coconut Oil (29%)
- 450g/16oz Hemp Oil (17%)
- 425g/15oz Olive Oil (16%)
- 113g/4oz Blend of essential oils (4%)
- 1-2 tsps. of glitter, petals or seeds to decorate
- 370g/13oz Lye (Sodium Hydroxide)
- 850g/30oz Distilled Water
The saponification process
The oils must be measured out by weight and placed in containers ready for use. In soap-making, all ingredients are measured by weight, whether solid or liquid.
Hard fats can be placed directly into the cooking pot to be gently heated; once they are liquid the remaining oils (except fragrance and essential oils) can be added.
When the oils are fully mixed and liquid, and the temperature is at around 100° C (212F), the heat must be turned off, and the lye-water may be added slowly to the pot. Remember to stir the pot constantly throughout.
As the the mixture cools and the lye reacts with the oils, the liquid in the pot will become cloudy and increasingly viscose – this is the saponification process beginning. At this point, blend the mixture in short bursts (around 5 seconds) with the electric mixer, gently stirring and scraping the sides in between each burst. With every blend, the mixture will become ever more viscose.
The finishing touches
When the mixture is almost cool, the essential oils and fragrances can be slowly mixed in, using the spoon rather than the blender. After this, any decorative items such as petals, seeds or even hemp leaves can be blended in. By now the true scent of your finished product will be apparent.
Finally, colorants can be added, with a range of techniques and methods for added visual appeal. To achieve a marbled effect, pour a little of the soap into a mould, and add dye to it, mixing well. Then gently pour more soap from the pot into the mould, using a spatula to achieve the desired level of intermixing. Soaps may be left in the mould for a few days until they fully set, and must be cured for up to three weeks more to remove all traces of lye from the saponification process.
The simplicity and flexibility of this method has won many fans, and there much benefit in having control over what is contained in skincare products used everyday by ourselves and our families. The recipe above does not contain any of the worrisome additives such as Sodium Lauryl Sulphate (SLS), which is ubiquitous in commercial products and has been implicated in health and environmental problems.
As well as peace of mind, making one’s own skincare products can represent a substantial yearly saving, and can be a rewarding experience to share with friends and family. Once the soap-making technique has been mastered, there are plenty of recipes for hemp-based shampoos, lotions, massage oils and moisturizers to try. With a little time and effort, it is possible to create an entire skincare range, and avoid ever having to buy commercial products!