I have several ferrocium rods which I have had nearly 20 years, and I live in a very humid climate, with no issues. However, I once had a problem with the tiny ferrocium rods for a zippo lighter. I always put the extra flints under the felt flap. I have been doing this for probably 20 years. There way one time when I went to refill my lighter that I noticed the flints looked "bubbly". A touched them and they all disintegrated. It only happened that once.