Definitions

antioxidant: A substance that inhibits oxidation, especially one used to counteract the deterioration of stored food products or personal hygiene products. 

emollient: Having the quality of softening or soothing the skin, moisturizing

emulsion: A suspension of small globules of one liquid in a second liquid with which the first will not mix; a mixture of two immiscible liquids

emulsifier:  An emulsifier is a surface-active agent that facilitates the mixing of two or more liquid substances that would separate into its component parts under normal conditions; has two ends--one oil-attracting end (hydrophobic) and one water-attracting (hydrophilic) end.

humectant: A substance that promotes retention of moisture

petrochemical: Relating to or denoting substances obtained by the refining and processing of petroleum or natural gas

preservative: a substance or preparation added to a product to destroy or inhibit the multiplication of microorganisms.

salicylic acid: a monohydroxybenzoic acid, a type of phenolic acid and a beta hydroxy acid.In addition to being an important active metabolite of aspirin (acetylsalicylic acid), which acts in part as a prodrug to salicyclic acid, it is probably best known for its use in anti-acne treatments. The salts and esters of salicylic acid are known as salicylates.

salicylates: chemicals that occur naturally in many plants, including many fruits vegetables, and herbs. salicylates in plants act as a natural immune hormone and preservative, protecting the plants against diseases, insects, fungi, and harmful bacteria. salicylates are also created synthetically and can be found in many medicines, perfumes and preservatives.

Preservatives vs. Antioxidants

Two things have a major effect on the shelf life of a product. One is bacterial growth and one is oxidation.

Firstly, what is the purpose of a preservative? it is to prevent the growth of bacteria. In any environment exposed to water, bacteria WILL grow. There is no exception to this rule. Even with refrigeration, eventually bacterial contamination of some kind will happen. Some of it is innocuous but some is dangerous, particularly to immunocompromised individuals, such as MRSA. And even if you have a healthy immune system, rubbing this antibiotic resistant strain of bacterial directly on your skin is not advised, amirite? Any product that contains water or water based ingredients needs a preservative. Period.

Some essential oils are anti microbial or antifungal, but not at the level of concentration used in products meant to be put on skin. For an essential oil to be a effective preservative, you wouldn't be able to use the product on your body. This doesn't negate their potential benefits, such as tea tree oil for dandruff, it just doesn't make them an effective primary preservative.

Secondly, what is the purpose of an antioxidant? An antioxidant prevents oils from oxidizing, i.e. going rancid when being exposed to oxygen. Some examples of antioxidants are mixed tocopherols (vitamin e), rosemary extract, and grape seed extract.Certain oils and butters are naturally high in antioxidants such as vitamin e. This means they have a longer shelf life than oils low in antioxidants. 


THE TAKEAWAY: oxidation has nothing to do with microbial growth. Just because your product will not readily oxidize doesn't mean bacteria won't grow in it. And just because you can't see the bacteria doesn't mean it's not there. Therefore, all good products will have both a preservative system and either naturally occurring or added antioxidants.