I have tested this in extreme conditions in the Caribbean. After submerged in salt water for 1 year in the heat and sand, the hologram color was boiled off but the plastic was still intact. It protected the keys and yes the keys are still readable. I could claim flood resistance for up to 1 year in extreme conditions, but collectability is destroyed. Keys still readable. A Caribbean Treasures 2023 Brass 10,000 Satoshi piece was the test coin.
This was more what I was thinking.
Yes, in the home for your seed / private keys steel / titanium seed plates are the best.
I have always had the niggling feeling in the back of my head, how will these coins with keys make out.
Personally, for a bunch of reasons I am shrinking my collection, but I still love the collectables. And I don't think any of us want to hear 'After my house was destroyed I managed to recover my collectables but I could not get read a bunch of keys' I admit it's an extreme edge case, but in the scheme of things the additional cost to someone making a coin to use the better papers is minimal.
-Dave