system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5/ Why do unused blades lose their sharp edges over time?

Answered-
I only use my skates once a year and the rest of the time they're sitting in storage. Every single year I have to re-sharpen my skates even though I've only used them once. What happens to the blade edge? No pressure is dulling the blade while they're in storage so I'm confused about why they become dull over time.
gpt
The fine edge oxidizes. If you were to look at the very thinnest part of the blade under a microscope, you'd see pitting and etching from rust - even stainless steels are not immune.

You can protect them to some degree by drying them thoroughly and then oiling them after use.