It is a 200ml mineral lotion, opened about eleven months ago, spent most of July in the door pocket of a car that gets properly hot. The texture looks slightly separated but it mixes back when I shake it. There is no date printed anywhere on the bottle that I can find. Do I bin it or does it just lose a bit of strength?
Mildly against the mood here. If you get through 200ml in a year you are not applying enough, and that is a far bigger problem than whether this bottle degraded. A proper face and neck application is roughly the length of two fingers, and full body is around a shot glass. At that rate a 200ml bottle is a couple of weeks of a beach holiday, not a season.
Look on the back for a small open-jar symbol with something like 12M or 24M in it, which is the months-after-opening figure. It is usually printed rather than embossed and it hides near the barcode. That symbol is about the formula staying intact once air gets in, and it is a different question from the expiry date, which is why bottles can carry both.
Heat and separation, bin it. Nobody can tell you how much protection it lost by looking at it, and the failure only shows up as a burn.
I kept a bottle exactly like this and got burned through it on a boat in June, which is how I learned. Now I write the month I opened it on the bottle in permanent marker and keep sunscreen out of the car entirely, in a drawer inside. Cost me one holiday and a peeling back to work that out.
@cue_carla · 3w ago · 3 replies
The general rule is that sunscreens are required to hold their stated strength for at least three years from manufacture, and if there is no printed expiry that three years is the assumption you are meant to make. What breaks that assumption is heat and light, which is exactly what a car door pocket in July delivers. Separation that shakes back in is usually fine on paper, but combined with the car I would not take it on a beach day.
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@back_of_envelope · 3w ago
That is what I do with anything questionable. Nothing bad happens from using it, you just cannot count on the number on the label, so put it where the stakes are low.
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@film_fridge · 3w ago
Is there a middle option, like using it on my arms for the commute and buying fresh for actual sun exposure?
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