Stability testing is a hugely important part of the product launch process.  Clients often come to me and ask me how long their product will stay stable and of course the answer is ‘well I don’t know unless we test it’.  While there are some educated guesses that can be made by looking at a formula, asking a few questions about the ingredients or manufacturing method or based on what I’ve seen before the truth is that to know one has to test.

Stability Testing

Stability testing starts off very simply with what I call a ‘boot camp’ test which is where we stress a formula in certain ways to see how it behaves in the short-term as a predictor for longer term stability.  This includes freeze/ thaw testing, centrifuge analysis and microscopic evaluation.   We also hold the samples in a hot and humid environment for a week to see how they fare.  If that stage is passed samples progress to a more standard protocol of 4C, Room Temp and 40C conditions over 12, 24 or 30 weeks (equivalent to 1 year, 2 years and 30 months which is the recommended shelf life for a typical cosmetic but is in no way mandatory).

We recommend products be tested in their final packaging (or packaging type if the exact pack hasn’t been chosen) as packaging choice can play a huge role in making a product more or less stable. Also doing this enables us to see if any product/ pack interaction is taking place.  We also test the bulk product in plain glass packaging as a reference point so as to get a good visual on the product during testing.  Different material types have different oxygen and moisture permeability which can influence how quickly a product will oxidise so again it is very important to know how your product/ packaging combination fairs, especially if you are due to retail or store your products in a tricky environment (high humidity, hot conditions etc).

Stability testing starts at $1500 per product and rises depending on the time-frame we test for and whether any additional stability markers are required.  These might include assaying for the presence of an active over time (to make sure your key active remains active during the shelf life),  micro testing or Preservative Efficacy Testing (PET is highly recommended at the beginning and towards the end of all stability testing over 12 weeks as preservatives can undergo chemical changes that render them less effective over time) or patch testing (to see if the aged product contains any irritants (quite useful when the product aroma is from oxidation prone essential oils.

Overall I would urge people to think of stability testing as an interesting window into the chemistry and potency of their product and a tool that enables the brand owner to go forward with confidence and pride and not just another cost with nothing glittery to show for it.  While glitter may sell the first time,  it is substance that keeps them coming.

Looking forward to working with you.

Amanda