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Stability testing a solid product
How do i test for stability of a product that is solid at room temperature and start to melt at around 50 degrees Celsius? Would it still be the same route as products with water in it? This is an anhydrous formulation with waxes and oils
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2 Replies
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Hi Jonathan,
This is what I know, and what I would consider:
1. The temperature range where your product starts melting- if your product is meant to be used in the Russian winter, it needs another melting point and texture than when it is going to be used in the African summer;
2. The texture of the product:
a. To check for graininess (even if it’s not apparent), keep the product at room temp. for 2-3 weeks, and then assess its texture; it should be smooth and homogenous, and if any graininess, reassess your method;
b. What happens to the texture in case the balm undergoes temperature changes (much higher or much lower than room temp) during transport and application? The product should always come to the initial texture when back to room temperature.
3. The container’s integrity: what happens to the balm in case it melts in the container? Does the container leak or does it remain sealed? How does the container react to changes in humidity?
To answer to 2b and 3, a simple method is to run three cycles as follows: 24h at 45C, 24h at room temp, and 24h in the fridge.
Check the texture and appearance of the product after each cycle, as some issues can reveal themselves earlier in the process. Also check if the product leaks from the container if upside-down/on the side when it’s melted.
I hope this helps.
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Thank you! this is very helpful 🙂
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