Source: The Encyclopedia of Antique Postcards©
Used with Permission from Susan Brown Nicholson - Deltiology@aol.com
Collecting vintage paper creates some special concerns regarding its preservation. If you like to keep antique photo or postcard albums complete as they were originally assembled, you will have even more problems. The real disadvantage is that most early albums were made of inferior green or black construction paper that leaves a residue on the postcard corners. If a top quality album was used, this slick paper didn't move or breathe leaving heavy indents on the postcards called album marks. Cards should be removed from these old albums.
The major enemies of paper are fire, water or humidity, dirt, sunlight, mold, and bugs. If you are investing large sums of money in postcards for your collection or dealer's stock, fireproof file cabinets or a vault is advisable. Collections can be protected in a safety deposit box, which is cool, dry, dark, and theft proof.
Separate each item with acid-free paper, glassine, or Mylar to prevent ink transfer. Stand cards on edge when possible, stacking causes damage to embossing and mechanisms.
Keep humidity at 50-65%; too low and the paper becomes brittle; too high and microorganisms grow. The temperature should be under 75 degrees. Heat causes faster chemical deterioration.
Sunlight is a great destroyer of paper. If you wish to display your framed collection, do not place items in direct sunlight. Instead, display them on interior walls away from natural light. When having your items framed, be sure to request museum mounting. If the shop doesn't know what you are talking about, select another store.
Nothing should ever be done to paper that cannot be easily undone. If an inventory must be kept, do it in pencil. If the item needs to be secured to album pages use only stamp hinges, photo corners with clear Mylar tops, linen or paper tape. Never affix any kind of tape to the front of your postcards.>
Dealers use plastic sleeves and album pages. Collectors should not, unless they are sleeves or pages of archival quality. A dealer's stock is constantly changing and cards are seldom in contact with this Poly Vinyl Chloride (PVC) storage system for long.
This PVC material will cause chemical damage to antique paper if left for long periods of time. In addition, postcards that are not in a humidity controlled environment risk water damage from condensation forming inside of the sleeves. This can be seen at outdoor flea markets. When items in plastic are exposed to the sun, they heat up creating condensation that can cause irreversible water damage.
Before you panic about the storage of your postcards, remember they have survived nearly 100 years in old deteriorating postcard albums. They probably will survive many more years with just a reasonable amount of care, but only archival protection will preserve them indefinitely.