This is true even of the materials in the oldest collections. Beech attributes the fresh colors of the Library's materials to the fact that the library's prohibition of photocopying its philatelic materials. There is a class of environmental agents whose effects on philatelic materials are not generally understood in so far as we are aware. These agents are the printing media used by computer printers and photocopy machines. Some collectors even use album pages where the philatelic material is mounted within boxes having shaded interiors.
Ordinary air can have an adverse effect on our philatelic materials.
The damage can be intensified when the air is laden with moisture. For removal of large amounts of water from the atmosphere, use an electric dehumidifier. Spread these crystals in a small saucer or similar container, carefully keeping the philatelic materials from contacting them. As small pools of water replace the crystals, discard the water and add fresh crystals. These crystals last for years because after they have absorbed water, they can be regenerated in a hot oven.