Replacement Flints

Does anyone know why my replacement flints dissolve into white
powder? Actually I don’t care why, really I want to know how to stop
it. I use the spring type welding striker to light my torch and have
a little metal container that holds the replacement tips. I’ve had
these tips for years but it turns out that they are dissolving faster
than I can use them. Now I know this is not a costly item but it irks
me. Would storing them in plastic help?

Orchid Rules! Karla in S. California