Nothing is worse than having to toss out your favorite lotions before they're used up. Homemade lotions have a shorter shelf-life as they tend to be made of fresh and natural oils and ingredients. They will go bad if you don't use them quickly enough. You'll need a preservative to make them last longer, and one effective method is a citric acid solution.
Homemade Lotion with Citric Acid
Heat 10 oz. water until almost boiling, then add 1 tsp. citric acid and allow it to dissolve into the water. Set aside.
Add all oils, glycerine, waxes and butters to a heat resistant mixing bowl.
Fill another cooking pot with water and bring it to a boil, then place the mixing bowl into the pot. This is called a double boiler, which is a gentle way to melt your oils for your lotion.
Stir the oils to combine them, and remove the bowl from the double boiler.
Blend the oils using an emmersion blender. As you blend, slowly add the water with citric acid.
Add the stearic acid. Keep blending. Your lotion should begin to get creamy and form stiff peaks.
Transfer the lotion to a clean, lidded storage container. Your lotion should last three to six months or longer if kept in the refrigerator.
Tip
While adding citric acid directly to store bought lotion isn't the best idea (it needs to be diluted to avoid irriatating your skin), most store bought lotions already have preservatives added. The best way to extend the life of these lotions is to clean your hands before you use them and store them in the refrigerator.