It might feel like an oxymoron BUT sunscreen which is required as protection from the sun, will spoil under direct sunlight. Which begs the question, where do you put sunblock when you are at the beach?
Sunblock may spoil if exposed to heat beyond 25 degrees celcius, which is basically a cool day at the beach. Applying sunblock before arriving to the beach is certainly a start but you will certainly need to reapply.
The first recommendation is to keep it at the very bottom of your beach bag. Away from direct sunlight. This will keep it as cool as physically possible.
Sunblock should also be stored away in a dark place. Which makes the ‘bottom of the beach bag’ suggestion plausible.
A second suggestion would be to order an ice bucket and place the sunblock in the bucket. This will certainly do the trick. Again ensure that it is away from direct sunlight even if it is in the ice bucket.
The truth is that sunblock does go through a large number of temperature and environmental changes. Air-conditioning, ice bucket etc. The best thing to do is to buy as small a tube as possible. That way, it is at least risk of spoiling.
If your sunblock has separated, then it is no longer effective. Also give it a sniff, if it smells off, it probably is!
Generally speaking sunblocks should not be kept from one year to another. Just like your tan, you’ve got to start fresh!