When making shampoos, conditioners or other hair care products at home, you need to also provide a way to prevent the product from spoiling. Several broad-spectrum anti-microbial preservatives are available to help prevent bacteria from growing. They work well in water soluble formulations, as well as both oil in water and water in oil emulsions. Another additive, Vitamin E, has anti-oxidant properties that help to prevent oils in hair care products from turning rancid. Available in craft and hobby stores and online, these ingredients are ready to use and shelf stable.

Wait until the hair care product formula you are making cools to below 120 degrees F. Most anti-microbial preservatives are heat sensitive and will degrade if exposed to temperatures above 120 degrees.

Measure the preservative in the amount recommended by the manufacturer. Most preservatives for homemade personal care products are between 0.1 and 1 percent of the total volume.

Add the preservative to the formula mixture. Open one gel-cap of Vitamin E oil and add it as well. Blend the mixture thoroughly with the stick blender to disburse the preservative completely.

Wash containers used to store your hair care product in a dishwasher with temperatures that exceed 160 degrees F to sterilize them. Refrigerate your finished product to further retard bacterial growth and oxidation.