Have you ever applied sunscreen, only to find your newly manicured nails soft and almost sticky!?
I just did my nails on Sunday with my favorite color of OPI nail polish, Miami Beet. But yesterday, I went running and it was sunny, so I slathered on a liquid T-Shirt by means of 70 SPF sunscreen on all exposed limbs. Now, my perfect, glossy manicure is matte and soft and getting little dents & knicks in it!
I just googled to find out why sunscreen ruins nail polish, and it seems as though sunscreens usually contain an "emulsifying agent" that is almost identical to one of the agents in nail polish remover. So it slowly dissolves nail polish. The only way to combat this is to wear gloves while applying the sun screen and/or use the spray type of sunscreen instead of the kind that you rub on like lotion.
And the only way to remediate the problem once it's occurred is to apply another layer of topcoat to halt the agent from softening your nail polish.
Just an FYI.