A clear, virtually colourless (the slightest hint of pale yellow) mobile liquid with a slight odour.
Preservative K offers a broad, balanced spectrum of effect against bacteria, yeasts and mould fungi.
The spectrum of activity is supplemented and balanced by the use of Benzyl Alcohol (effective against gram-positive bacteria) and Phenoxyethanol (effective against gram-negative bacteria).
Effective in anionic, cationic and non ionic systems.
The ingredients that make up Preservative K are all palm free.
Benzyl alcohol, Phenoxyethanol, Potassium sorbate, Aqua, Tocopherol
The individual materials that make up Preservative K are listed on the Cosmetic Ingredient Database (Cosing) here.
Effective in oil in water (O/W) and water in oil (W/O) emulsions so can be used in creams and lotions for all skin types.
No direct hair care usage but it is effective in hair conditioners, hair packs and shampoos.
Use at 1% but it is safe to go as high as 1.5% for example when using herbal infusions and decoctions. Always check with your cosmetic safety assessor to ensure the percentage is correct for your particular product.
Add to Stage 3 (below 40°C) as it is not heat stable above 80°C.
It is only effective when the pH of the finished product is below 5.5 It is completely ineffective if the product is higher than pH 5.5.
It is soluble in glycerin but only partially soluble in water.
Clays are notoriously difficult to effectively preserve as they tend to pull the preservative in to itself, leaving the water stage under preserved. We have found in our own tests, that Preservative K was effective when used at 1.5% but there are many other variable to take into account and you should only rely on the results of your own challenge tests.
Although some of the older publications still suggest using drops as a measure, this is not accurate as dropper sizes vary. Always weigh the amount of preservative used to get the correct percentage needed.
Do not blend different preservatives with each other unless you are experienced in this area and can have the result tested for efficacy. If you are adding extra materials to a base product, you may need to add extra preservative as well. Ensure the same preservative as the base product is used.
None when used in the correct manner.
For more information and guidance on making your own skin care products please see Aromantic's books and eBooks in our Publications section.
These notes are not meant to replace medical guidance and you should seek the advice of your doctor for your health matters, The formulae are given in good faith and are intended for educational purposes only. They have not been evaluated or tested in any way and Aromantic Ltd. makes no claim as to their effectiveness. It is up to the reader to ensure that any products they produce from these recipes are safe to use, and if relevant, compliant under current cosmetic regulations.
Preservatives are needed for most cosmetic formulations that include water. There are some companies that have very stringent manufacturing procedures to ensure the hygiene of the product and the ratio of some of the materials may make the product quite stable against contamination. Shampoos can sometimes do this as they are often very alkaline. However, that alkalinity is not very comfortable on the scalp.
Vitamin E used to be referred to as a preservative because it preserved the shelf life of the product. This was, however, only from the oils in the product going rancid. It is not a preservative by today's accepted standards.