Many different oils can be used to make soap. Each one imparts different qualities to the final product. For example, an oil that is high in saturated fats has good lathering properties and adds to bar hardness; an oil that is high in unsaturated fats helps with moisture and conditioning. This chapter describes a number of oils that are commonly used in soapmaking.
Apricot kernel oil comes from the kernels (seeds) of the fruit. It is high in fatty acids and vitamins A, C, and E. It is also high in unsaturated fat, which means that it adds to conditioning and moisturizing properties, but does not help with cleansing or bar hardness. Apricot kernel oil is typically used at 15 percent or less in soapmaking recipes.
Avocado oil is a heavier oil pressed from the pit of the avocado. Depending on the type of extraction, the color varies from green to yellow, which has little effect on the color of the final product. Avocado oil adds to conditioning and moisturizing properties in soap. It is typically used at 20 percent or below in recipes.
Canola oil is an economical soaping oil that is fantastic when a recipe needs a lot of working time or a neutral color. High oleic canola oil is the best choice as it will not go rancid as quickly as traditional canola oil. Canola oil is best used in conjunction with hard oils such as coconut and palm oil. It can be used up to 40 percent in soapmaking recipes.
Castor oil, an extract of the castor bean plant, is a thick, sticky oil with a distinctive odor. It is light yellow in color, but this doesn’t typically affect the color of the final product. Castor oil creates large, luxurious bubbles, but is typically used at 8 percent or below in recipes to avoid tackiness.
Cocoa butter is extracted from the cacao bean. It has a distinctively nutty, chocolate-y aroma and is used in making chocolate. Despite its name, it has a hard and crumbly consistency and must be melted before being mixed with lye-water. Cocoa butter comes in two forms, deodorized and natural. The deodorized version, sometimes called Maria grade, is usually whiter than natural cocoa butter and does not smell like chocolate.
When used in cold-process soap, cocoa butter contributes to bar hardness. If it’s used over 15 percent, the soap may become difficult to cut and be prone to cracking. The soap may also take on a slight cocoa fragrance.
Used in cooking, baking, and soapmaking, coconut oil is typically expeller pressed from the meat of coconuts, then bleached and deodorized. Coconut oil extracted with solvents is less desirable. Coconut oil has a variety of melt points: 76°F (24°C), 96°F (35.5°C), 101°F (38°C), and 110°F (43°C). They all work for soap, but the 76°F–melt point version is the most commonly used.
Coconut oil creates lather with large bubbles and helps to cut down on oils and grease. It has a high cleansing ability, so some find it harsh on the skin if used above 25 percent. Its long shelf life and high stability make it a staple in soapmaking.
Coffee butter is a luxurious butter that smells just like a slightly burnt cup of coffee. It is a blend of coffee seed oil and hydrogenated vegetable oils, giving it a soft, buttery application. Pale brown in color, it can impart a lovely natural tan color into the final soap, as well as a subtle roasted coffee scent. Coffee butter contains between 0.5 and 1 percent natural caffeine. It has a shelf life of about one year. It does not contribute much to the lather or hardness of the bar, but is considered moisturizing. It is typically used at 10 percent or less.
Hempseed, or just hemp, oil, does not contain tetrahydrocannabinol (THC), a psychoactive constituent found in the seeds. Depending on the degree of refining, its color varies from light yellow to dark green. It is used in skincare products because of its high proportion of essential fatty acids.
In soap, it provides a nourishing yet small lather. Shelf life can vary depending on the type of refining. Unrefined hempseed oil has a short shelf life of 3 to 6 months. Refined hempseed oil has a shelf life of 12 months. It is typically used at 20 percent or less in soapmaking recipes.
Macadamia nut oil has a rich feeling on skin and may be used in heavy moisturizing creams. In soap and cosmetics, it is often used to replace mink oil, which many people prefer to avoid. It is stable in soapmaking, although it does not produce copious bubbles. Macadamia nut oil provides conditioning and moisturizing qualities. Because it does not contribute much to bar hardness or lather, it is typically used at 10 percent or less.
Mango butter comes from the seed of the mango fruit. The seed is pressed, and the resulting oil is refined, bleached, and deodorized until it is ivory in color with a creamy texture. It has a shelf life of 6 months to a year. In soap, it adds conditioning and nourishing properties. It is typically used at 15 percent or less in soap recipes.
Meadowfoam oil is derived from the seeds of the meadowfoam plant (Limnanthes alba). It is unusual in having almost 100 percent long-chain fatty acids, which makes it extremely emollient and moisturizing. Meadowfoam has a shelf life of up to three years when stored in a refrigerator. Because it does not add to bar hardness or lather, it is typically used at 20 percent or less. Using more produces a slightly softer bar with smaller bubbles.
Olive oil is available in a variety of grades. While extra-virgin olive oil is not necessary for soap recipes, it is important to use a pure grade. Some methods of extraction, such as the last pressing, include the use of chemical solvents, which may be present in the final product. These chemical solvents can lead to acceleration of trace.
Extra-virgin olive oil (olive oil pure) allows for a very long working time, and is a staple for designs with complicated swirls, lots of different colors, or accelerating essential oils, such as cinnamon. If a recipe calls for olive oil pure, it is best not to substitute with olive oil pomace, which will trace more quickly.
Olive oil pomace is made by removing the last bits of oils and fats from the paste left over from pressing extra-virgin olive oil. It contains high percentages of unsaponifiables, and is known to speed up trace. This oil is used when a recipe needs to set up slightly sooner, such as in some of the layering projects, or recipes that have a textured top. Extra-virgin olive oil can be substituted in these recipes, but be aware that the trace times will be longer.
All types of olive oil produce an exceptionally mild soap with small bubbles, suitable for sensitive skin and babies. Unlike other oils, it can be used up to 100 percent in soap recipes. When fresh, the lather is slick. Olive oil soap ages beautifully, improving its lather over time.
Caution: The exception is “light” olive oil, which often doesn’t work in soap at all.
Palm oil comes from the pulp of the fruit from palm trees. In soap, palm oil helps to stabilize lather, adds to making a harder bar of soap, and acts as a secondary lathering agent. When used in conjunction with coconut oil, the lather is stable and large. Because of its hardening ability, palm oil should be kept to 25 percent or less of your recipe. For soapmaking, look for RBD (refined, bleached, deodorized) palm oil.
Palm oil is becoming increasingly controversial because of its environmental impact (see What Is Sustainable Palm Oil?, below). Over half of the recipes in this book don’t use it, so although palm oil is a wonderful oil for soap, it is not required.
Palm oil is grown in a number of South Asian and African countries. The plantations require massive amounts of land to keep up with the demand, and some unscrupulous plantations illegally clear surrounding rainforest and peat, leading to the destruction of orangutan and other wildlife habitat. Certified Sustainable Palm Oil (CSPO) is sourced from plantations that do not log in primary forests or areas of biodiversity or endangered species.
The Roundtable on Sustainable Palm Oil (RSPO) oversees CSPO certifications. In addition to ensuring that habitat is not being destroyed, the organization works to reduce the use of pesticides and fires for clearing, and advocates for the fair treatment of workers according to the international labor rights standards. If you would like to use palm oil in your soap but are concerned about the harmful effects of unsustainable palm harvesting, ask your vendor if they source RSPO-certified palm oil.
Palm kernel oil (PKO) is obtained from the kernel (the nut-like core) of the palm plant. PKO comes as flakes and is solid at room temperature. It contains highly saturated fats that contribute to bar hardness in soap and lather stability. When used at amounts higher than 15 percent in soap, it will accelerate trace and the soap can become brittle and waxy.
Peach kernel oil is rich in vitamin E, making it a great addition for mature skin. A light oil, it is typically a pale, neutral color. Peach kernel oil contributes to a stable lather when used with coconut oil, but it does not add to bar hardness. Though it can be used up to 25 percent, it is typically used in smaller amounts.
Rice bran oil is derived from the outer layers of rice: the bran and the germ. These layers are packed with antioxidants, essential fatty acids, and vitamin E. It produces small, mild lather, similar to olive oil, and can be used in place of olive oil to lower bar cost. Though it can be used in cold-process recipes up to 100 percent of the oils, it is typically used at 50 percent or below.
Safflower oil is an inexpensive oil that is moisturizing in soap and creates a mild, low lather. It can be used interchangeably with sunflower or canola oil (after running through a lye calculator). Standard safflower oil has a fairly short shelf life of one year, so look for the high oleic version to increase the shelf life. It can be used up to 25 percent in recipes.
Shea butter is produced from the nut of the African shea tree. In its most unrefined state, it is a gray, smoky-smelling product. When fully refined, bleached, and deodorized, it turns creamy and white.
In soap, shea butter has great moisturizing abilities, and because it is a well-known ingredient, it provides ample label appeal. It is not a good lathering agent on its own, and can speed up trace. It is typically used at 10 percent or below in most soapmaking recipes.
Soybean oil is available as a liquid and as a hydrogenated (solid) oil. Both add to the conditioning properties of soap. Because of its price, soybean oil is an attractive filler oil for soap recipes. It produces a mild and thin lather. Though it has a shelf life of up to 12 months, liquid soybean oil does not contribute to bar hardness. It is typically used at 50 percent or less in a recipe.
Sunflower oil is full of essential fatty acids and vitamin E, which condition and moisturize skin. It has a short shelf life, so either keep it in the fridge or look for high-oleic versions, which tend to be more stable. When combined with olive and palm oil, it helps to produce a rich, creamy lather. Use sunflower oil at less than 20 percent in soap recipes, or it will result in a soft soap.
Sweet almond oil is a food-grade oil pressed from edible almonds (Prunus amygdalus var. dulcis), not the poisonous bitter almond (P. amygdalus var. amara). Sweet almond oil has many vitamins, including A, E, and B6. It contributes to conditioning and moisturizing skin, but will make softer bars. It is typically used at 25 percent or less and has a shelf life of 9 to 12 months.
Many soapers, especially those who raise livestock, prefer to soap with rendered animal fats in place of vegetable oils. Animal fats have been used for hundreds of years in soapmaking and they can create wonderful bars of soap that are very hard and white bars with mild, creamy lather. Tallow and lard, from beef and pork respectively, are the most common, although some soapers have been known to use more exotic fats, such as bear or beaver.
The fat from any type of animal may be used, although they will all have slightly different SAP values, generally within the range of .134 to .141. Tallow has a SAP value of .138 to .141; lard’s is .139–.141. There are a few outliers, such as lanolin, with a SAP value of .075, and mink oil, with a SAP value of .160. Always check the exact SAP value for any fat, or use a lye calculator; small differences in SAP value can have a big effect on the amount of lye needed to turn the fat into soap.
When making soap for other people, it’s important to be aware of nut allergies. Depending on the severity of an individual’s allergies, the use of nut-based oils (and other nut-derived ingredients such as exfoliant shells, described in chapter 5) can cause adverse reactions. Here are some of the more commonly used nut oils that might cause a problem for certain individuals. When labeling soap for sale, make sure to list every ingredient used in the soap — including carrier oils and oils used to disperse colorants — to help keep customers with allergies safe.