What makes a great soap recipe is intensely personal. Some people prefer plenty of lather, but those with hard water have a difficult time getting any lather unless a particular blend of oils is used. Others prefer a slick conditioning bar or a lot of exfoliation in their soap.
Designing your own recipes also means your favorite ingredient can make an appearance in all your products, or you can try out some new additives to help improve your skin’s look and feel. You can increase the amount of butters to provide more moisture to dry skin, or use aloe vera, essential oils, and other plant extracts for homeopathic effects. You can design a mild cleansing bar for use on children or create a shampoo bar for cleaning hair.
Designing new recipes can be exciting and a little intimidating, but don’t worry, you don’t need to reinvent the wheel to create your own versions. Before you dive in, though, become familiar with a few established recipes. Choose ones that sound good, with ingredients that you and your skin will like. Once you have some experience, trying variations with a tried-and-true recipe is a great place to start creating your own recipes.
Modifying existing recipes with different oils and extracts will give you the confidence to use common guidelines and oil properties to create your soap from scratch. The general rule of thumb is to replace oils with similar oils; that is, replace solid oils with other solids, and liquid oils with other liquids. For example, olive oil is a good substitute for canola oil, but cocoa butter is not. Read chapter 5 to learn about usage rates for individual oils.
The colors and essential oils may also be swapped out, but make sure to find out how a new ingredient performs in cold-process soap before you make a whole batch. Some essential oils will accelerate trace, for instance, and some colors morph or just disappear.
The best way to determine how a new recipe will turn out is to do a small test batch, wait the full 4 to 6 weeks for a cure time, and evaluate it. As with most things, practice makes perfect — pretty soon, you’ll be formulating with confidence and achieving the bars you want each and every time.
Caution: If you change any of the oils in a recipe, you must run it through a lye calculator again to ensure the correct amount of lye is used. In fact, whenever you modify a recipe in any way, always run it through a lye calculator, as the water and lye values can change with even small adjustments. Getting the lye-water and oil proportions are critical to getting your soap to trace and cure properly.
All of the recipes in this book list the weight of each ingredient and the percentage of the total oil content. Whether you are increasing or decreasing the original recipes, the ratio of lye, oils, and liquid must remain the same. To do something simple like make a double batch, just multiply all of the ingredient amounts by 2 or run the recipe through a lye calculator using the increased amounts. To cut the recipe in half, simply divide the amount of each needed ingredient by 2. It’s always a good idea to double-check even simple math with a lye calculator.
Here are some additional tips for designing recipes with specific properties.
Water discounting is an advanced technique that involves holding back some of the liquid (usually water) that is mixed with the lye in the beginning. Some soapers do it on purpose to make their soap cure faster and produce harder bars that won’t shrink over time as excess moisture evaporates. Using less water means that the recipe will trace faster, which is why this is an advanced technique.
Note that when utilizing a water discount specifically to add tea or another ingredient at the end of the soapmaking process, you will not receive the benefits (curing faster, harder bars) described, because you end up adding the same amount of water in the end.
Oils at room temperature can be liquid (olive oil) or solid (coconut oil), but it is difficult to generalize final bar properties from that state. For example, you would probably assume that oils that are solid at room temperature produce a harder bar of soap. This assumption is correct, but it is the only thing you can assume when formulating recipes. For example, coconut oil produces amazing lather, but cocoa butter, which is also solid at room temperature, does not have great lather when used on its own. This is why it is important to find a mixture of oils that produce the final end result you want.
Oils work synergistically to produce a great bar of soap. For example, although shea butter adds to the moisturizing and conditioning properties of a soap, if you use it at 100 percent, the bar will not lather well. If you combine it with coconut oil, however, it will produce a bar that balances the skin-care properties of shea butter with a wonderful lather.
To illustrate this further, here are three recipes that use different quantities of olive, coconut, and palm oil. Olive oil contributes a small lather with conditioning properties; it is good for sensitive skin. Coconut oil creates large lather, has good cleansing properties, and adds to bar hardness. Palm oil stabilizes the lather and contributes cleansing and bar hardness.
See chapter 4 to learn about the properties and SAP values of specific oils.
You can use liquids other than water to make your lye solution. Coffee, tea, milk, beer, and wine can add interest and skin-loving properties, plus they have great marketing value on the label, if you are selling your products. It’s important to prepare each liquid appropriately prior to adding the lye, as misuse can not only ruin your soap, but also be dangerous during the process.
Caffeine constricts blood vessels and may temporarily help to even out skin tones, so coffee and teas that contain caffeine are thought to help reduce skin redness. Numerous cellulite-reducing products on the marketplace utilize caffeine.
Coffee, both ground and brewed, absorbs odors, so soap that contains some coffee, either brewed or ground, is ideal for removing pungent odors from hands. Liquid coffee also tints the soap a rich brown; however, you probably won’t detect much, if any, lingering coffee scent due to the saponification process.
With teas, the resulting color is always brown or olive green. Even red elderflower tea, for example, will turn brown during saponification. Green tea can initially color soap a lovely green, though the final soap turns brown as it cures. Bergamot-based teas give soap a creamy color and, depending on the strength of the infusion, may impart a faint bergamot scent after saponification. Minty teas also give soap a brown, creamy color and the aroma tends to linger a bit.
When using coffee or tea in place of water, chill it to nearly ice-cold before adding the lye, to prevent it from scorching (this smells awful!). Use the coffee/tea, brewed to normal strength, just as you would water, replacing it in any recipe in the amount specified for the water.
Teas do not work well on their own as colorants. The tannins in the tea react with the lye solution by turning dark or by completely leaching out and leaving no final color. If the tea has caffeine in it, it usually will turn brown in soap, but not always a pleasing shade. Black tea has the highest level of caffeine and produces the darkest color.
The best way to add tea, if you are trying to maintain color, is to make a strong slurry of tea, freeze the tea in ice cube trays, water discount with your lye (see What Is a Water Discount) and then add the ice cubes (factoring in the water discount) after you add the scent. This will help preserve some of the colorant but not all of it.
Rooibos and herbal teas can be prepared this way. Since they do not contain caffeine, they do maintain some color. Rooibos turns a red/brown color in soaps, for example.
Beer and wine add a few positive attributes to soap but offer an interesting soaping challenge. They contain fantastic antioxidants, and the natural sugars increase lather. The color of the alcohol greatly affects the final appearance of the soap. A dark merlot will result in a much darker final bar than a soap made using a chardonnay, so keep that in mind when designing a recipe around a color palette. The end results are worth the extra time needed to add the alcohol.
Beer, wine, and champagne require some additional preparation, so leave extra time when using them and follow safety procedures even more scrupulously than usual. It is critical to boil off the carbonation and alcohol from these liquids before using them in soap, or a volcanic eruption may occur when you add the lye. To do this, boil the liquid uncovered for 10 to 15 minutes, then put it in the fridge, uncovered, and leave it for 24 hours. Boiling reduces the volume, so you need to start with roughly twice the amount of liquid as the recipe calls for.
Beverages that have a high alcohol and/or sugar content become extremely hot when lye is added to them. Both alcohol and other clear liquids, such as teas, work best when chilled, and it’s important to add the lye slowly to the cooled liquid. This helps keep the overall soap temperature down, preserves a more neutral color, and helps give the time you may need to work with a more intricate recipe.
Fruit and vegetable juices and purees are packed full of nourishing vitamins, minerals, and beautiful natural colors. Vitamins A, B6, and C are found in many vegetables and fruits, along with copious amounts of antioxidants that fight free radicals. Carrots, tomatoes, and cucumber skins can provide beautiful color in soaps, though be aware that soaps colored with purees will fade over time. If you’re selling your soap, adding purees adds flair to your label and sets your product apart from the competition.
When adding juices to soap, always add the lye directly to chilled juice. Add a liquid puree at thin trace or as a portion of the water phase. It is important to add the juice or puree with the lye-water or at thin trace so that the pH of the mixture is high enough to kill off any possibility of mold or bacteria in the fruit. Whenever possible, use pure fruit juices that you have prepared yourself.
Purees must be finely ground; never use chunks of fruit or vegetable in soap. Larger pieces of fruit or vegetables will eventually mold or cause a discoloring “halo” effect. You can use pure fruit juice in place of all or part of the liquid/water portion of your recipe. The puree can be added at thin trace or watered down and used as all or a portion of the lye-water. Purees and fruit juices do not add scent to the soap.
Many purees or fruit juices do go brown or fade over time. There are some exceptions — carrot juice and pumpkin puree, for example — that keep their color for some time, but for the most part, purees and fruit juices are not ideal coloring agents. To help the colors last, store soaps in a dark place. The amount of time the color will remain in the soap varies with the additive, with greens typically being the shortest-lived before turning brown. The shelf life of soap made with fresh veggie or fruit juices and purees is about one year, even if the color fades before that time.
Cleopatra is said to have bathed in donkey milk daily to keep her skin radiant and youthful. While it is no longer common to bathe in a tub full of milk, milk soaps are increasingly popular for their skin benefits. All milks (nut and animal) contain skin-loving fats and proteins. Some, such as goat milk, contain lactic acid, which encourages skin cell turnover and smoother skin. Milk soaps tend to have rich, creamy lathers and leave the skin feeling soft from the excess fats.
When buying milks, look for ingredients without additives, such as thickeners or sugars. Thickeners (guar gum is a common one) can significantly speed up trace and make it difficult to complete intricate designs. Added sugars in milk will cause excess heat to form, which can result in the soap puffing out of the mold like a soufflé, as well as discoloration.
Soaping with milk requires a somewhat different process. Milk that becomes too hot from the lye will scorch, causing discoloration and a foul odor, so for best results, work with frozen or slightly thawed (slushy) milk. The more slowly you add the lye to the frozen milk, the less chance you have for discoloration and scorching. Start with about 1 tablespoon of lye, sprinkle it on the cubes or slush, stir until dissolved (it will melt the ice), and repeat 1 tablespoon at a time until all the lye has been added. Placing the lye-water container into a cold-water or ice-water bath will also help to keep it from getting too hot.
Some new soapers like to use INS numbers. INS numbers refer to a numerical value that describes the properties an oil will have when reacted with sodium hydroxide to make bar soap. It relates to the degree of unsaturation and molecular weight of the oil. The theory was developed in the 1930s and over time, the meaning of acronym has been lost. Some people believe INS stands for Iodine iN Soap.
The iodine value is an old-fashioned way of determining the level of saturated versus unsaturated fats in various oils. Oils with more saturated fats dissolve less iodine, have lower iodine values, and give harder soap. Oils with more unsaturated fats dissolve more iodine, have higher iodine values, and give a softer soap.
An INS number is supposed to tell at a glance how an oil will perform in terms of hardness, conditioning, lather, and cleansing. Finding the perfect balance of oils is the holy grail of soapmaking; there would be no more thinking about how to design the best recipe for conditioning ability that also lathers well. In reality, it doesn’t quite work that way.
For one thing, INS numbers cannot accommodate the variations among oils from crop to crop. Depending on where an oil is grown, how it is harvested, and how the climate changed from one batch to the next, its properties for making soap will be slightly different (really, truly!).
For another, soap recipes turn out differently depending on a variety of factors, such as where you are soaping. Soaping in a hot, dry room can produce different results than soaping in a cold, humid garage or basement. The actual bars of soap also behave differently depending on how you use them (note the difference when using hard water versus soft, for instance). Soaps also lather differently depending on the temperature of the water — the warmer the water, the better the lather.
In theory, a perfect bar of soap would result from a recipe with an INS number of 160, based on the INS numbers of all the oils used. In practice, however, a recipe using 100 percent cocoa butter, which has almost a perfect INS number, would produce slimy bars that don’t lather and leave a sticky feel when rinsed off. Learn to create a great bar based on the properties the oils give to the bar, rather than relying on the imprecise method of INS numbers for determining your formulas.