Stearic acid is a saturated fatty acid that has an enormous variety of uses as an ingredient in food, cosmetics, and industrial products. It is extracted from many types of animal fats, vegetable fats, and some oils. It is also often used to change the consistency or melting temperature of a product, as a lubricant, or to prevent oxidation. The versatility and cost effectiveness of the acid makes it a popular ingredient in countless types of products, from candles and soap to lotion and margarine.
One of the most popular uses of stearic acid is in the production of candles. It is often used to harden the wax and strengthen the candle. It also has an impact on the melting point of the wax, improving the durability and consistency of the candle. For these reasons it can be found in most craft stores in the candle making section.
Stearic acid is also commonly used in the production of soap. In fact, soap may have been accidentally discovered in the ancient world by people trying to extract oil from animal fat; this process was likely similar to how stearic acid is extracted from animal fat. Soap made from animal fat, however, suffers the drawback of having low water solubility, which can result in a residual film on bathtubs and skin. Therefore, rather than as a primary ingredient, this acid is usually used as an additive. It can harden soaps and give shampoos a pearly color and consistency.
In the world of cosmetics, stearic acid is used to form a stable base for deodorants, lotions, and creams. It helps to bind and thicken the products so they adhere smoothly to the skin and have a longer shelf life. The fact that the melting point of this acid is well above human body temperature tends to prevent cosmetics from running and streaking when applied for extended periods.
This substance is also used in many food products because it is stable during storage and frying. Many margarines, spreads, and shortenings are formulated with it as well. Even though it is a saturated fat, it seems to have little effect on cholesterol levels in the blood. The reason for this seems to be that a high proportion of it is converted to oleic acid, which is a monounsaturated fat.
Other uses of stearic acid include preventing oxidization. It is commonly used to coat metal powders such as iron and aluminum that are used in fireworks, allowing them to be stored for longer periods. It is also used in some metal polishes to help prevent the oxidation and rust that can occur on metal parts of tools.