How long will my cream or lotion last? Which is the BEST preservative? If I add “x” preservative, what is the use-by date please? These are questions we receive streams of emails and calls about.
We do try to explain and help, BUT this is not something that we are able to give a definitive answer for. Yes, we do sell preservatives, both synthetic and natural, but even those manufacturers of those products will not commit to a shelf life. There are so many variables involved. There is NO ‘one size fits all’ preservative system, but some will overlap depending on your product and your preferences of ingredients.
If you are a home crafter, a small business just starting out or a larger enterprise, the shelf life of your creations is something of utmost importance. There is only one way to know the shelf life – it’s called ‘Challenge Testing’. What is this? This means you send your product to a professional laboratory for testing. The lab evaluates your products for safety and stability and advises the best before date for the product. If they find that your formulation is unsafe or unstable (goes off) you can often work with them to try and get through the issue.
Some products are more susceptible to spoilage – those with organic ingredients such as milks, proteins, clays etc, and of course any that contain water.
Cost? Yes, you are right, it’s expensive to determine the shelf life, and the cost will vary from lab to lab. We are unable to make recommendations for specific labs, and suggest you Google or use your Yellow Pages to find someone you will be comfortable working with (try “cosmetic stability testing laboratory”).
Mostly anhydrous products (those without water) only require an antioxidant (such as Rosemary Oleoresin Extract), however, do bear in mind how and where your product will be used. Scrubs for example, are often used in the shower or bath, and water is easily introduced into the product, therefore, stability testing (as well as a preservative system) is recommended.
Do I have to have my products tested?
Well, ultimately this is of course your personal decision, just as the type of preservative system you choose to use, and you do need to make this decision yourself. If you ask us, we’ll always advise that testing is recommended – it’s good business practice, a little like insurance and overheads, something that has to be costed into the final cost of your products.
If you are not going to have your products challenge tested, the best advice we can offer after GMP is to use the “Best Before Date” on the preservative system you have purchased
Basically, when all is said and done, it’s your choice, that’s why we make our own products, but we just want you to produce safe cosmetics for you, your family and customers.