Shea butter is a waxy natural fat that is extracted from the shea nut. It is traditionally used in many African countries for its healing and moisturising properties, although it is edible and is also traditionally used as a cooking fat. Rich in skin-friendly vitamins A and E, shea butter has become a popular ingredient in many commercial skin products. When making skin care preparations at home, you can apply shea butter directly to the skin, or otherwise melt it with oils to create a balm. However, in order to incorporate shea butter into a water-based lotion, it will need to be emulsified.
Choose an emulsifier. Water and oil do not mix, so in order to create an emulsion it is necessary to add an emulsifying agent. A familiar emulsifier is egg yolk, which is used to bind oil and vinegar into a thick creamy mayonnaise. The process of making a cosmetic emulsion is similar to the process of making mayonnaise, but instead of egg yolk you will need to use some other form of emulsifier. Beeswax has some emulsifying properties but usually can't be depended on to create a stable emulsion, i.e. one that won't separate. You can buy emulsifying wax from skincare ingredient suppliers.
Melt the shea butter and emulsifying wax/beeswax in a bain-marie. If you don't have a bain-marie you can use a heatproof bowl placed over a saucepan containing a small amount of boiling water. It will help to break up the shea butter in order to speed the melting process. Stir the mixture until it has become liquid and is well-combined.
Remove the oily mixture from the heat. If you wish to add any other vegetable oils (such as almond or avocado oil) to the mixture, do so now. Do not add any volatile essential oils at this stage, as the heat will cause them to evaporate. You are now ready to add the water.
Warm the water to around 65ºC; this is so as not to reduce the temperature of the oily mixture. If you add cold water directly to the mix you will cause the melted shea butter to solidify. Slowly add the warm water, stirring continuously with a hand-blender. Keep adding and stirring. You may find the mixture separates, but keep blending.
As the mixture starts to cool it will begin to thicken. You can now put your hand-blender aside and start mixing by hand, but you may need to stir quite briskly. When the mixture has reached room temperature it is safe to add any essential oils for fragrance and aromatherapeutic effects, or you may prefer to keep your lotion unscented. Stir thoroughly to ensure the essential oils are combined. You can now decant the shea butter lotion into small jars or bottles.