WriterMilly AhlquistWriterAnnabelle Letten
Self-preserving in practice
Experimenting with ways to keep the amount of free water to a minimum means that liquid products like shower gels can become entirely self-preserving. By balancing the levels of water, butters and oils, safe synthetic cleansing agents and beautiful, natural materials, it's possible to create cosmetics made almost entirely of materials which are beneficial to the skin or hair.
It's a careful, delicate process, however, one that takes time and effort to apply to more and more products. The dynamics of the formula must be carefully balanced in order to produce a beautiful product that is effective, practical and long-lasting, without having to utilise a synthetic preservative system.
It’s a question of balance - and a change of attitude - learning to work with our microbe friends rather than against them. “Highly preserved products are capable of wiping out the microflora that protects our skin,” explains Helen, “and we want our products to be better than that. We want them to deliver great effects for the customer in a safe and natural way. This has led to us having a relationship with our microbial friends.”
Cosmetic scientist and product developer Daniel Campbell describes the difficulty in balancing water and oil in a self-preserving version of Dream Cream, a product type known as an emulsion which binds oil and water together.
He explains, "We needed to ensure that the emulsion was loose enough to allow the oil to be absorbed by the sebum that sits on your skin, but bacteria really like to live between a loose interface made of oil and water. What we needed to do was to create a balance where the emulsion was loose enough be absorbed into your skin but tight enough so that microorganisms couldn’t get in there. We found that by reducing the water slightly and moving up the quantities of oil, glycerine and cocoa butter, that we were able to strike that balance - and that it was a very specific balance.”
Self-preserving or preservative-free?
Preservative-free is a tricky piece of phrasing. It implies that a product is completely free of preservatives - something experts Jon J. Kara and Donald S. Orth take issue with in their publication, Preservative-Free and Self-Preserving Cosmetics and Drugs: Principles and Practice (1996). They explain, “Usually, multiple-use aqueous consumer products in their current containers cannot be made preservative-free merely by removing preservatives from the formula. The term self-preserving is more appropriate than preservative-free for most aqueous products containing a chemical system that kills microorganisms and/or prevents their growth.
In other words, nearly all of the time water-based ‘preservative-free’ products contain a preservative - just not one recognised by the EU. For example, honey, salt, kaolin, clay, talc, calamine and cocoa and shea butters all have preservative qualities when used in the right quantities. In addition, preservation techniques like creating solid products, reducing the amount of free water in a formula and using sealed packaging and shorter shelf lives can also be used to create self-preserving formulas.