Today I was looking at a coin I'd put away in an air-tite about six months earlier, and I noticed a faint, diffuse brown spot that I was pretty sure hadn't been there originally. I got out a magnifier (really I just put on two pairs of reading glasses at the same time, but don't let your family see you that way) - and there at the center of the spot was a tiny fiber of some kind that had been trapped against the coin when I closed the capsule. I wonder what would have happened in six years instead of six months, and I also wonder how many coins stored with the best intentions are damaged for a similar reason. I've got one of those air-puffer things that photographers use to blow dust off lenses, and plan to use it liberally in the future.
Dust and foreign matter getting caught on coins causing spots is nothing new. So is tiny tears in the mylar on 2X2's that cause localized tarnishing.
I use canned air blow out any debris in the airtite halves, then rinse the coin with acetone and transfer it into the capsule without ever touching it. I contend that the TPGs are far too lax with their slabbing process. I've seen all kinds of junk trapped inside slabs. Many coins also develop nasty fingerprints from careless handling at the TPGs.
I was always under the assumption that the propellant used for "canned air" would cause damage to coins? As for the TPG's, I do not understand why the slabbing room is not a "Clean Room" where non-reactive latex gloves, protective clothing (non-fiberous), hair hats and safety goggles were required. Too often, a hair gets sealed in a slab or in some cases, a piece of dandruff or skin. These are disastrous for any kind of coin.
As long as the contents are expelled as a gas, no harm can come to the coin nor the plastic. Tetrafluoroethane is inert.
What brand of canned air are you using as I think I want to do some tests to satisfy my own curiosity since I have come across many cases where the ole ear syringe just doesn't have enough power.
How about an oil-less compressor? Pay for itself eventually, unlimited supply of compressed air, pump tires, paint, pump stuff up and air brush - etc. as a free bonus. Add a proper filter for coin use just in case.
