The Concept of Cosmetic Shelf Life

The Concept of ‘Shelf Life’

The performance characteristics and attributes of a cosmetic or personal care product will undoubtedly change over time. This will happen with every single product that you make, no matter how perfect the original formulation. It is the extent of these changes which occur over time, that may make a formulation acceptable or deem it unstable, making it unsuitable without further formulation R&D.

According to the Institute of Personal Care Science, "The shelf life of a product should be determined by the length of time it is expected to maintain acceptable performance characteristics and attributes; without the formation of hazardous by products."

The concept of ‘shelf life’ covers every single aspect of a product not only the "science". It includes the physical feel of the product, the aroma and its intensity, and it includes appearance from a consumer perspective. The science states that it includes microbial growth, separation, and efficacy of actives, but if a product "looks" or "smells" off to a consumer it will not move in a retail market regardless of the lack of microbial growth!

These parameters are crucial to controlling the quality of a product during and after development, and they in turn become the foundation of the formulator's product specifications.

Any given product formulation should aim to exceed a 3-year shelf life which may seem like a lot when you are a "newbie" formulator, but with time, education and experience this is not overly hard to achieve! The goal of a three year expiry is partly due to scalability. Products that make their way into a retail setting should hold the ability to scale up if a product requires it, and as such it should be able to be manufactured in batch sizes that provide 3 years-worth of product sales.

Manufacturing in these size batches help companies to obtain a reasonable return on investment while still incorporating the best actives, materials and product stories possible. Needless to say, 3 is kind of a "unicorn" in cosmetic manufacturing for this reason!

With a lesser shelf life the cost of research and development, raw materials, labour and even the packaging can be significantly more per unit. This of course can affect the bottom line, but also causes unnecessary compromise on the materials used, and the performance that can be obtained.

In some cases, product formulations may only achieve a 2-year shelf life, but this would be considered the minimum acceptable shelf life for a cosmetic or personal care product.

There is sometimes a common train of thought surrounding small batch production, natural and/or organic formulas. To this end it is assumed that these products are NOT as stable, do NOT have as long a shelf life, and are NOT comparable in terms of quality and stability! THIS IS INCORRECT!

Any organic or natural product formula CAN meet and often exceed the 2 - 3 year shelf life period if properly developed and formulated using a high degree of ingredient selection and specification expertise. Small Batch Production if anything, CAN extend the quality, stability and ultimately the Shelf Life of a product based on the care and attention that goes into a singular batch. 

The bottom line is that if a formula can’t achieve at least 2 years shelf life it should be NOT be formulated and moved to retail until it can. Remember, 3 years or more is the ideal, while 2 years should be considered an absolute minimum.

So the question becomes....

HOW DO WE TEST THE SHELF LIFE OF OUR PRODUCTS AT A SMALL BATCH PRODUCTION STAGE? 

This is a part of your Good Manufacturing Practices and your Standard Operating Procedures. There are several ways that a small Start-Up can attain a Gold Standard for their Quality and Stability. One of the many ways is through the purchase of Dip Slide testing, a second option is through the purchase of a small incubator and agar plates. There are some simpler "small batch" testing that can be conducted, but truth be told the TAMC and the TYMC Colony Counts are critical! If this is not something you are prepared to be doing independently, find a good local lab and have them complete it for you. It is NOT an outrageous sum and can attest to the safety, the stability and the overall quality of your product. It also makes a statement about the dedication and commitment of you as a formulator to your consumers and clearly says that you take their safety and needs very seriously. 

No matter which country you are selling your products in, no matter how large or small scale your business operation is today, there is no way you can be sure of the safety and stability of your product formulation without conducting suitable stability testing. For this reason, stability testing should be considered an integral part of formulation development with the appropriate time and budget allocated. In addition, it is a part of the GMP Requirements of ISO 22716 which states "...you have assured the quality and stability of the product you are launching into the market". 

In Canada, when we hit SUBMIT on Health Canada's CNF form...... and in the United States, when we hit SUBMIT on the FDA's Voluntary Cosmetic Registration Program, we are attesting to following the GMP Guidelines as outlined in ISO 22716 (including the quality and stability bit)!

In many courses over the years I have heard things about how to determine the Shelf Life of products. Things like the following:

"Use the shortest known expiry of your raw materials for your product expiry"

There are so many things that this does not account for like the interaction of the raw ingredients with each other. A simple example of this is a little thing called an antioxidant! We know that because an antioxidant decreases oxidation, it in theory increases the expected shelf life! BUT DID YOU KNOW that by using too much antioxidant OR too much preservative, we actually lessen the expected shelf life? 

There are so many actions and interactions; so many causes and effects that without proper alignment from start to finish you may end up with a haphazard product with a less than impressive shelf life and therefor a less than impressed consumer base! When you think about the associated costs, think about the brand damage that just one unhappy client can cause! I think you will agree that the investment of proper stability testing is more than justified!

Cause and Effect:

• Supplier Selection
• Ingredient Selection
• Ingredient Ratio/Weight/Volume
• Formulation Method
• Ingredient Phase Assignment
• Storage of Ingredients
• Packaging
• Labelling (with storage instruction indicated)
• Synergy Interpretation 
• Ingredient Impact (ie. Vanilla Absolute requires Stabilizer to avoid formula browning)

As you can see from the very limited list above there is much to consider with every single formula. 

A solid "foundational" company formula can take years to develop and test and move to market! This is NOT written to discourage you, but to enlighten you! Turning a passion or a hobby into a profitable business takes time, education and commitment! It is so so so well worth it though, as it can fill your soul to the very brim! 

If any of you have questions about stability, shelf life, formula development or anything in between I welcome your comments and questions and will do my best to address them all!

In Joy and Wellness,