A picture frame typically has a dust cover on the back. As it’s name implies, this cover is designed to keep dust out of the frame package. However, it is really more important than that. Properly covering the obverse of a frame keeps out dust, insects and airborne pollutants that could cause harm to the frame contents. Kraft paper has historically been the covering material of choice, although truly not the best. In my opinion, the best covering material is Tyvek. You know, the stuff they wrap houses in. The stuff that Fed-Ex envelopes are made of. The reasons are many: Tyvek is tough; insects won’t eat it (silverfish love to eat paper); it provides a moisture barrier; it buffers changes in humidity and atmospheric pressure; it provides a barrier to many airborne pollutants.
-- Always do the Right Thing the Right Way the First Time - if you can figure out what that is! Ken, Spring Branch, TX