Here, we must reiterate that the use of preservatives in skincare is absolutely essential if you are formulating something water-based. However, there are some products, mainly anhydrous formulations, that don’t require a preservative; these can be face oils, body butters and balms. Anhydrous products are usually able to exist as ‘preservative-free’ systems as they are not prone to microbial contamination; however products that will continually have water introduced to them by the user such as oil-based salt scrubs should also be taken into consideration when contemplating whether or not to include a preservative. Anhydrous products stored in the bathroom need preservatives because the bathroom environment is moist and warm, and these are optimum conditions for bacteria and mould to thrive. Determining the solubility of a preservative system is key to knowing which preservative you can add into a product. For example, adding an oil soluble preservative in a facial toner primarily consisting of water is not going to provide the product with efficient protection. Preservation spectrum It is important to find a preservative system that is broad spectrum, meaning that it is effective against bacteria, mould and yeast. Working pH range This is the optimum range for the preservative; it is important to consider this when formulating as you want the best chances of preservation for your product. However, you must think about whether or not the preservative is compatible with the product you are formulating.
