It may sound counterintuitive, but oils and fats are the main ingredients in soap. Basic soap has three ingredients: oil/fat, water, and lye. Mixing those with lye and water 'saponifies' the oil/fat in a curing process that takes 24 hours - 6 weeks, depending on the method and recipe. What remains is pure soap and a small amount of intentionally un-saponified oil/fat that does the moisturizing.
Each oil/fat in a recipe is chosen for a specific reason for either its end properties in the soap or to balance the recipe between saturated and unsaturated fats. Here is a list of the oils/fats we use in our soaps and what they are used for.
Stable lather and conditioning. Similar properties to olive oil. Canola contains Vitamin E, and Omega 3 & 6 fatty acids.
Conditioning, moisturizing, and creamy lather with high stable bubbles. It boosts lather by making soap more easily dissolve in water and draws moisture to the skin.
Conditioning, moisturizing, adds hardness for a long lasting bar, and creates a stable lotion-like lather. Cocoa butter is high in Vitamin E and other antioxidants. It does not fully saponify, so it keeps its properties in the soap after curing.
Very cleansing, adds hardness, abundant lather with large fluffy bubbles, natural white color. It can even produce lather in hard water and sea water.
Conditioning, moisturizing, and strong stable lather.
Like beeswax and cocoa butter, it does not fully saponify leaving more hydrophylic (water loving) qualities to help moisturize dry skin. Jojoba is actually a liquid wax and absorbs into the skin remarkably well.
Conditioning, adds hardness, mild stabilizing very creamy lather, naturally white. Makes a long lasting bar. Before vegetable oils were commonly available, lard and beef tallow were the main fats. It is still revered today for it’s high stability and moisturizing properties.
Very conditioning but low cleansing. A gentle oil high in antioxidants (Vitamin E and polyphenols). Makes a very soft soap and is best paired with a harder fat or oil. Castile soap is made with 100% olive oil.
Medium lather, mild cleansing. Similar to canola and sunflower oils.
Gives a silky feeling to bars, mild stabilizing lotion-like lather, medium hard, long lasting bar. Because it does not fully saponify some remains in the final soap. High in vitamins A and E, fatty acids and minerals. It has been said that shea butter can help with skin blemishes, dry skin, wrinkles, and stretch marks.