Preservation of active ingredients is a big deal in beauty – it's what keeps your favourite skincare delivering the same glow-giving results on the third month of use as it did on the first. Some ingredients, like vitamin C , are unstable on a chemical level and can be hard to preserve, so ampoule-sealed vitamin C could theoretically be a good workaround. But as Nausheen explained, potency preservation goes beyond that: "Brands should technically be doing packaging compatibility tests on all of their products. These are basically specialised tests which show how your product reacts with the packaging itself over time," she added. For example, a tube of cream might be fine and secure but once that tube is in your bathroom (where you shower and bathe, raising the temperature of the room) or in a bedroom in a hot country, there's no guarantee that the stress of that heat won't alter the product potency. "The packaging should be properly stress-tested under heat, up to 50 degrees, to make sure it doesn't degrade or leach into the product," said Nausheen.