Moisture: the safe deposit box's worst enemy.

[Jobu]

A safe way to use the silica gel beads is to buy a plastic tupperware container, poke a lot of holes in the lid, and put the silica beads in there with the lid closed. It will still be open to the air but ought to contain all of the gel in case of what seems like a fairly rare meltdown.

According to Wikipedia (proceed with some caution), there appear to be a few things that react with silica gel: "Silica gel is non-toxic, non-flammable, and non-reactive and stable with ordinary usage. It will react with hydrogen fluoride, fluorine, oxygen difluoride, chlorine trifluoride, strong acids, strong bases, and oxidizers."

My guess is that the inital meltdown was due to one non-silica product accidentally being mixed with the silica, causing the problem. For those that use dessicants I would recommend using only a single product rather than mixing multiple products. Also, as I think I mentioned in my post in the original thread, the dessicants that look a lot like cat litter are primarliy composed of non-dessicant material - you can get dessicants that are pure silica gel and therefore pack a lot more wallop per unit volume.

So, after all that babble, my suggestion to Bill is not to put your collection in containers but to put the gel in one instead. That way the cards are more open to the air. When working in the tropics, at the end of the day I always put my gear in an airtight bag with a container of gel and it always worked great (given the conditions I just used a sock but never had any issues - I would not recommend that for cards).

For a follow up question and a bit of a piggyback, does anyone know how water proof PSA, SGC, etc slabs tend to be? Are they even open to the air? If they are fully sealed that would influence concenrs about humidity and exposure to the air.