I have a bunch of these saved from various shipments I received. Do they work well to keep humidity away from coins? Do they expire? Thxs Pat
Eventually, all will expire. I've always used the 40gm "Rechargeable" in the aluminum pack. I bought a couple of them about 20 years ago, and I'm still using them. http://www.jpscorner.com/silica-gel-humidity-control.html
I use them but make sure there is no way for them to come into direct contact with the coins if broken open.
What I found that is rechargeable online is really too much for me (Minimum 2 cubic feet). I keep my coins in shoe boxes or in file boxes. I guess the little packs found on the site listed above should be enough. Pat
The silica packs are rechargeable. Most people don't know that, and since they are fairly cheap, just use new ones. I live in the arid West, so moisture isn't a problem luckily. You can just place them in your oven on a tray not to be used for food and heat them up to 220 F or so for an hour.