Posted 01/03/2009 11:04 pm
Yes, they're useful, if your coins are sealed up in a safe, safety deposit box or other reasonably airtight container.
My only caveat: don't let the coins come into prolonged contact with the "crystals" themselves, especially the blue/pink ones - they contain cobalt salts.
Some years ago as an experiment, I crammed a film canister full of bright shiny copper coins and blue indicating silica gel (we haven't had copper circulating coins here in Australia since 1990, so that's how long ago we're talking about).
After a few years, I opened the tube up and had a look. The gel was still blue... and the coins were all kinds of funky colours, and corroded in spots, too, where the crystals had been touching them.
Used in moderation, silica gel is good at keeping the moisture down. But you can have too much of a good thing.
My only caveat: don't let the coins come into prolonged contact with the "crystals" themselves, especially the blue/pink ones - they contain cobalt salts.
Some years ago as an experiment, I crammed a film canister full of bright shiny copper coins and blue indicating silica gel (we haven't had copper circulating coins here in Australia since 1990, so that's how long ago we're talking about).
After a few years, I opened the tube up and had a look. The gel was still blue... and the coins were all kinds of funky colours, and corroded in spots, too, where the crystals had been touching them.
Used in moderation, silica gel is good at keeping the moisture down. But you can have too much of a good thing.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
