The following is excerpted from “Postcard enemies… and remedies,” an article by Chris Wolff in the Postcard Collector, August 1984.
Is your postcard collection dying? If it hasn’t been stored properly, it slowly but surely is. Poor storage procedures can damage a collection just as surely as fire or flood. However, most damage can be prevented.
First of all, remember that a postcard is simply a small rectangle of printed paper. Paper is one of the most common materials of daily life, yet it is also one of the most fragile and difficult to preserve.
For hundreds of years after paper was invented in China in A.D. 105, paper was made from pure cotton or linen rags or from vegetable fibers. These materials made a fine, strong, lasting paper. In the mid-1800s the growing demand for paper led to experimentation with wood pulp as a paper material and it was soon being used in commercial paper production. The main problem with wood pulp paper is that the chemicals used in the manufacturing process cause problems later.
The key to maintaining a postcard collection in good condition lies in optimizing the environment where the collection is housed and the conditions under which postcards are handled. Keep one thing in mind: Moderation. Postcards, like people, want it neither too hot, too cold, too wet or too dry, too bright or too breezy, or subjected to too much handling.
More harm has probably been done to postcards by people than by any other cause. Oils and soil are not easily removed from cards. When handling and examining cards, make sure your hands are clean and gently lift the cards by the edges.
The manner in which you store your cards can hasten or delay the deterioration process. It is the sulfites, left in the wood pulp during its processing, which react with light to form free molecules of sulfuric acid. Moisture in the air interacting with the sulfuric acid begins the destruction of the paper.
Acid in the paper will also migrate. If you place a postcard with a high acid level in contact with a postcard with a lower acid content, the acid will migrate from the high concentration paper to the lower concentration paper. Then both cards will deteriorate. The solution to acid migration is to place postcards into individual envelopes so that no card touches another.
Take care in selecting your storage envelopes. Most envelopes are made of polyethylene, lypropylene or polyvinyl chloride (PVC). These plastic materials are inexpensive but have major drawbacks. PVC degrades over time and the plasticizers (which make the material pliable) used in manufacturing the polymer can attack the card stored inside the envelope just as acid can. Acetate envelopes are marginally better.
The best envelopes for long-term storage are those made of Archival Type D Mylar. Mylar is Dupont’s trade name for its polyester film. Type D Mylar has been tested and approved by the Library of Congress Paper Conservation Laboratory. It is strong, nearly impervious to gaseous diffusion and, for a plastic, has a high melting point. It is, however, relatively expensive.
At the other end of the expense spectrum is cellophane; it’s inexpensive but, when it shrinks, it may warp cards stored inside. It is best to avoid it entirely.
If you choose to store your cards in albums, select a sturdily constructed type with smooth heavy rings and solid hinges. Do not use albums with large rings. It is better to have many thin (1”) albums with fewer pages each. All albums should be equipped with page-lifters front and back, to keep the first and last pages from being damaged. Albums should always be stored upright. If the album is laid flat and other items are piled on top, you risk pressing and damaging the cards in the bottom album. Select album pages with oversize pockets where the postcards can slip in and out easily without binding.
If you choose to keep your cards in file boxes, select those which are sturdy, clean and free of harmful chemicals. Metal files are best, especially if they have smooth edges, sturdy rollers and a non-toxic finish of acrylic-based paint and baked enamel. Wooden drawers or boxes should be treated with two coats of polyurethane varnish or lined with Mylar to keep acids in the wood from migrating to the cards. Shoeboxes have a high acid content; acid-free cardboard boxes are available though they cost more. Cards should be filed loosely, but not so loosely they slide around, in drawers or boxes.
One of the worst enemies of postcards is the air we breathe. If it is too dry, cards will become brittle. If it is too wet, the glue holding the 2-ply card stock will soften and the plys will separate. The best range is between 50 and 60 pct relative humidity. Keep air circulation around cards to a minimum.
If you expose your cards to too much light, not only will the colors fade, but the heat will dry the paper and make it brittle. The ultraviolet portion of the spectrum also acts as a catalyst and the sulfates within the paper will form free molecules of sulfuric acid.
Store your cards in light-tight boxes or in albums on a dark shelf. Never hang framed postcards where direct light can hit them and always use a special type of glass, available through art shops and framers, that filters out the harmful ultraviolet rays.
Vermin can also be a problem. Cockroaches and silverfish will eat the paste in the cardstock. Mice will nibble on the edges of cards for the paste too. Take prompt action if you notice the signs.
Lastly, we come full circle to the major problem - people. The safest way to show cards to others is in albums or on display boards when the cards are safely protected from fumbling fingers. Postcards are fragile. In the long run they will deteriorate. But many problems can be prevented or delayed. With care, cards can travel safely through time to bring enjoyment to future owners.