Preservation of Postcards

 

The best way to take care of your cards is to only handle them with clean white cotton gloves while wrapping each one individually in buffered paper to help neutralize contaminants before placing them in rigid sleeves. They should then be stored in acid free archival boxes that are carefully monitored for a constant level of proper temperature of about 68 degrees and low humidity at 35% percent in a room closed off to all light.

While there are collectors who will go through these lengths to protect cards purchased for investment, they are too extreme for most of us who wish to interact with our cards. A balance must be found between cost, use, and their care, measured against the purpose they serve for us. While all cards should be given at least some level of protection, many of the procedures described below are both time consuming and expensive. One needs to consider if it is worth spending five dollars to repair a card purchased for a Quarter. But even these cards will one day become scarce if they are left to deteriorate. Many of us give these matters little thought as collecting postcards is just an enjoyable hobby. But whatever our purpose for collecting is it must be remembered that to some degree we all become custodians of history and this must be respected.

As hobbies have turned into collectable markets a number of sources for archival and conservation material for cards have developed. There are many good plastic products now designed specifically for the storage of postcards. In addition there are many good albums, boxes, and other storage material made for photographs that can be adapted for cards. Likewise many artist materials traditionally made for the repair of books can also be applied to postcards.

Acid

The paper used in postcard production is made up of cellulose that is derived from organic materials. A traditional source of cellulose for papermaking was cotton or flax from which rag paper is obtained. But by the late 19th century these traditional methods could not meet the high demand for large quantities of cheap paper. Paper made from ground wood pulp, mechanical paper, was substituted but it only produces a weak product and is high in lignin that cause it to quickly deteriorate. After decades of experimentation a practical method of making paper from wood pulp was finally developed. But to break down the harder fibers found in wood and remove most of the lignin it has to go through much cooking and bleaching in which chemicals are added to hasten the process. The finished product, chemical paper, contains residues of this process and some remaining lignin, which acidifies, causing the paper to turn yellow and become brittle as it ages. The alum rosin used in sizing many printing papers can also turn highly acidic when exposed to chlorine. All paper with acid content will eventually crack and break at the gentlest touch.

Even though chemical paper was in wide use when postcards first began to be made, individual printers used a variety of paper types. While rag paper was too expensive for most commercially printed cards, rag content was sometimes added to chemical pulp in varying percentages to improve its quality. The more rag content a paper has the less contaminants it contains to age it. On the other hand, mechanical pulp can also be added to lessen cost but its acid forming lignin will speed up deterioration. By the 1930’s with fewer publishers in the postcard business and the need to keep production costs low, almost all cards began to be made with chemical pulp. Many linen, postcards of this time now look much older than some cards printed fifty years earlier. It must be noted that linen postcards were not made from linen and contain no rag content. The name derives from the texture embossed into its surface.

All postcards regardless of their inherent acid content can be chemically contaminated by secondary exposures. The acids that form in postcards will migrate from one to another, so a card relatively free of chemicals can be contaminated by lying next to a card of poorer quality. Non acid free boxes like most cardboard is usually made from mechanical pulp that is high in acid content and can damage cards stored in them. Acid will also migrate thought the air so the two paper surfaces only need to be in proximity to one another for damage to occur. When cards are sealed within a box the airborne acid concentrates within it to maximize damage.

An alkaline mist containing magnesium oxide or calcium carbonate can be sprayed onto a card to help neutralize its acid content. It is applied as a mist so not to cause moisture damage. While it may not totally neutralize all the acid in paper it will at least slow its aging. This process however often leaves a chalky residue behind. There are also acid neutralizing tissued papers made that are buffered with alkaline. They will help in neutralizing acid content when cards are wrapped in them but this procedure is basically for long term storage. None of these procedures will repair acid damage that has already occurred.

The easiest way to prevent acid migration is by proper storage. Postcards should never be placed in contact with other paper but kept in plastic sleeves or album pages made from polyethylene or polypropylene that will not transfer any chemicals onto the cards. They should not be placed in ordinary cardboard boxes for permanent storage but into one of the many types of archival boxes now available.


Oils

Oil and grease can be very damaging to a card. It not only holds and attracts additional pollutants to a cards surface but mold and insects are atracted as well. In addition oils may also stain cards and contain acids that will directly attack its surface.

It is difficult to impossible to remove oils from postcards once they have moved into its fibers. Absorbent papers gently blotted against a card’s surface may remove some oil if the card was freshly contaminated.
While some oils can be airborne, the primary source of oil contaminants is from human touch. Most postcards have past through many hands over their lifetime absorbing much into their fibers. Theoretically unsleeved postcards should only be handled with white cotton gloves. On a more practical level they should at least be handled with freshly washed hands and then only by their sides. Any fingerprint will damage a postcard even if you cannot see it.


Smoke

The organic nature of paper allows it to breath and absorb any pollutant in the air. While the severity of this type of contamination will vary widely depending on how cards are stored and the air quality of region they are located in, they are all very susceptible to damage by smoke. When exposed to smoke from a fireplace or stove postcards can absorb soot that can blacken them permanently. Much of this damage is accumulative as the carbon particles too small for the eye to see slowly build up. The more common threat to postcards is from cigarette smoke. Here the added nicotine content will cause exposed cards to turn a dark yellow brown and become brittle. While this effect is only observable over time it is far more damaging than one might expect.

Less noticeable pollutants such as sulfur dioxide and nitrogen dioxide from the burning of fuels are found in high concentrations in urban areas and they can also slowly seep into postcards. These chemicals do not only discolor postcards, they will also deteriorate the card itself as they turn acidic. Real photo postcards particularly suffer from these pollutants as they will chemically react with the silver in their emulsions.

There are quite a number of paper cleaning powders on the market that can be applied dry to a postcards surface then brushed off. With gentle rubbing they will remove contaminants from the paper’s surface without damaging the card but they cannot remove those contaminants that have been deeply absorbed into the paper’s fibers. Ethyl alcohol (rubbing alcohol) can be used sparingly to clean the surface of real photo cards for it evaporates quickly and will not dissolve gelatin emulsions as water can.

Storing postcards in plastic sleeves or album pages is a good protection against airborne pollutants though not 100% effective. Cards in general should be stored away from windows, kitchens, furnaces, and other obvious sources of airborne contaminants. The safety of a postcard collection is also a good excuse to improve one’s health by creating a tobacco free environment.

Keeping postcards out of closets or even rooms that contain household chemicals such as cleaners and detergents can also add life to a card. While not considered smoke they will give off airborne pollutants no matter how carefully a container may be sealed. Those containing sulfur compounds are the most dangerous for they can easily be transformed into acids.


Albums

When postcards were first collected few had any regard to the effects storage habits would have on the life of the cards beyond the life of the collector. The act of collecting paper was somewhat new, and it started in an age when a great many new chemicals were entering the world whose long term effects were not yet known. It was common practice to place cards into albums or in metal tins that were sold for just such purposes. There were basically two types of postcard albums, both of which were made from acid rich paper. One had pre-cut slots into which cards could be placed. Cards that were once in such albums often have diagonal marks on their corners from acid migration and contact pressure. They may also have dark marks that were transfered onto them from the black pages of an album. The second type of album contained solid pages as they were often used as scrapbooks into which a variety of content would be pasted in. Postcards that have been torn from these albums often have residue of glue and paper on their backs. The acid from pieces of album pages still stuck to a card will continue to damage it. Album pages were often made of the cheapest paper available and their acid content is much higher than that found in any postcard. When all unprotected paper surfaces lie next to each other in the concentrated form of one of these albums, damage is enhanced. Glues used to paste in cards like rubber cement can cause great discoloration while casein based glues often soak into the card and harden becoming impossible to totally remove without damaging the paper.

More modern albums can also cause problems. There are many albums made for photographs used by postcard collectors that have a sticky corrugated paper base under a plastic sheet. The irregular surface causes a transfer of yellowish stripes across the card’s back from chemical damage from the glue, and sometimes similar glossy stripes will appear across the front from pressure against the plastic (ferrotyping). Some albums have magnetic qualities to hold objects in place but they also are magnets for all sorts of pollutants that can speed up a cards deterioration. Many plastic albums are made from poly vinyl chlorides (PVC) that give off acidic fumes that damage the cards they hold.

The damage caused by exposure to any one of these types of albums cannot be reversed. All foreign matter stuck to the back of a postcard should be removed as it can be assumed it will continue to damage the card. Depending how album residue is adhered this can be painstaking work. After all the loose material is removed by hand, a blade may be employed to scrap off the remainder of. This must be done so carefully as not to remove anything beyond what is pasted onto the card. Some glues like gum Arabic may be easily removed as they tend to lie on the paper surface, but more liquid type glues may have been absorbed into the card and are now permanently part of it. The glue may also be tested to see if it is water soluble. Removing glue with water is also tricky for it must be done in stages. Enough water must be applied to dissolve the glue but not to cause water damage. It must also be quickly blotted up from the card before it has time to be reabsorbed into the paper.

Cards should only be placed in album pages made from polyethylene or polypropylene as they will not transfer harmful chemicals to the card. They will also offer some protection from any contaminants emanating from the album itself. While many binders are made from materials that give off gases that will harm cards, totally archival albums are available in various forms but they can be quite expensive. It should also be remembered that albums do not protect cards from residue when they are placed in them back to back. Contaminants from one card can easily pass over to a pristine card under these conditions.


Tape

While cracks and tears often appear on cards as a result of their becoming brittle due to acid damage, many simply suffer from rough handling. Often it is a combination of the two. The obvious solution to many collectors was to place adhesive transparent tape across the damaged area. But as the tape dries out over time the plastic will fall off leaving behind an unmended tear and a crusty residue that continues to yellow the paper.

Yellowing caused by tape is not removable and any chemicals that may have been absorbed into the paper will continue to damage the card even after the tape is removed. To prevent further damage any plastic tape on a postcard should be removed if possible. Some tapes may still retain high adhesive qualities and will pull up paper with them, so much caution and discretion must be observed on how to proceed. All sticky residue left behind by tape can be removed with adhesive removers made specifically for paper products. Dry adhesive residue should be carefully scraped off.

If the tear or weak spot on the card absolutely need some support there are alternatives. Transparent mending tissues for book repair are a good choice for repairing postcards. Self adhesive tape of this type should however be avoided even if labeled archival as they may further damage the paper. The best method is to use a thin piece of Japanese rice paper cut to size and pasted onto the card with a vegetable starch or methyl cellulose paste. This is a traditional method of book repair. Another alternative if the damaged area is small is to use a peelable stamp hinge, as used by stamp collectors. These must be chosen with caution as almost all hinges manufactured in the United States have very high acid content.

If a card is in a fragile state due to tears, cracks, or creases, and you are uncertain of how to proceed, the card can always be stored in a ridged plastic sleeve. This will prevent any further physical damage while the cards future is contemplated.


Plastics

All plastics are petroleum products that can be composed of a variety of different chemicals. It is most common found in the form is polyvinyl chloride (PVC) from which a variety of products are made. This type of plastic is inherently unstable and will emit hydrochloric acid as it deteriorates. Postcards stored in plastic sleeves or album pages made from this material will suffer acid damage turning them yellow and brittle. Airborne acid migration from storage boxes or albums made from this material will also damage cards.

There is no way to repair acid damage created by exposure to polyvinyl chlorides.
The only plastics that should come in contact with postcards are those made to remain stable such as polyester, polyethylene, and polypropylene. They are all used to manufacture a large amount of products ranging from postcard sleeves to album pages. Polyester, usually found under the trade name Mylar D, is a usable stable plastic but few postcard related products are made from it. The proper use of plastics are a card’s first line defense against damage.


Light

For the most part colorants do not effect the aging of a postcard but are a element of a card that is subject to aging. Whenever a colorant is exposed to light, the energy from the ultra-violet portion of the spectrum will interact with the colorants molecules and damage them. This damage may cause them to darken, change color, but most often fade. This effect also varies from color to color as some will fade very quickly (fugitive), while others are quite resistant to damage (lightfast). Blacks rarely fade for they are mostly carbon based, and carbon is already a basic element and cannot be broken down further. Since the late 1920’s many more inks have been made from dyes instead of pigments and are more prone to fading. Because of their smaller molecular structure it takes less ultra violet energy to break their chemical bonds. The same is true for postcards that have been hand colored with watercolors rather than with oil paints. Pigment based oil paint was rarely used for coloring except on some real photo postcards.

The image on a real photo postcard is created by the interaction of light with a photosensitive emulsion that is chemically fixed when the desired exposure is reached. But not all of these cards were fixed well, especially if created by a amateur. To save money chemical baths were sometimes diluted or used past the time their reactive properties were spent. As unexposed silver salts left in the paper are exposed to light they will continue to darken the image.

Paper is not naturally white but must be bleached to achieve that appearance. Not all postcards were printed on white paper, some had dyes added to their pulp during manufacture to obtain softer tones or actual colors. When exposed to the sun these colorants can bleach out to varying degrees (lightburn). If only one area of a card is partially covered during a long exposure to light, a discernible demarkation will become visible.

There is no way to repair light damage to postcards.

Postcards should be kept away from light as much as possible. While sunlight is the primary source of ultra violet rays, indoor florescent lighting can be very harmful as well. If a postcard is framed, which is generally a bad idea, it should at least be kept out of direct sunlight, which it true for any work of art. An alternative is to make a high quality copy that can be discarded after being damaged by light.


Inks

Some inks as those used in chromolithography can contain a fair amount of varnish. Other cards received an entire coat of varnish to help protect their surface. When two varnished finishes lie against one another under pressure in a warm environment that can increase their tact, they will have a tendency to stick to one another. If pulled apart abrasive marks may appear on the card’s surface where the varnish has now been damaged. If the ink’s bond to the paper is weak whole sections of the printed image may come off.

While printing ink does not normally cause problems with a postcards stability the ink used to write messages onto them often does. Iron gall ink was commonly used before the advent of the ball point pen. Unfortunately it contains free acids that will deteriorate the paper it is written upon. The paper’s surface can sometimes be seen crumbling under wide swatches of this ink.

More modern writing inks have a tendency to fade, which does not destabilize the card but can lessen its historic value as the message upon it slowly disappears. Many modern inks are also water-soluble, which makes then susceptible to running and staining the postcard

There is nothing that can be done to repair damage to a card cause by ink or varnish.

Cards should be stored in plastic sleeves or album pages to prevent the ink or varnish from one card from damaging another. They should not be stacked or stored under pressure as a varnished surface may stick to its plastic protector. Unprotected cards should never be stacked face to face. It is best not to write on a postcard at all but if necessary never write in ink.


Moisture

Moisture can be a problem for certain colorants. While it has little effect on oil based pigments, certain aniline dyes that began being used in the late 1920’s were not waterproof. When exposed to moisture they will sometimes run leaving a pink stain behind (pinking). Postcards that are hand colored with watercolor are also susceptible to water damage. Watercolors always remain soluble and will dissolve, run, and pool when exposed to excess moisture.

Moisture can also damage the paper postcards are printed on. Since paper is an organic substance any water it absorbs will cause swelling. When this water evaporates it will do so at an uneven rate across the paper’s surface causing it to buckle and the ink to possibly crack. Because real photo postcards are heavily coated on one side with baryta and emulsion they also dry unevenly when wet. In this case the moisture problems manifest as curling. Photographs must be exposed to water as part of their processing, which is why they were traditionally glued down to boards afterwards. While real photo postcards were made on heavier paper stock to help control curling it remains a problem. A real photo card left exposed to the open air will absorb the moisture in it and curl.

Wet spots caused by constantly changing levels of humidity can cause oxidative damage to the cellulose in paper. this can appear as brown marks, dots, or smudges similar to oxidative damage on cut fruit. This is often mistaken for mold. When moisture is combined with heat it acts as a catalyst creating greater damage to the paper.

Ink and watercolor stains or runs, as well as oxidation damage are beyond repair. If a card has buckled due to water damage it may soaked in a water bath until it becomes completely flat as it swells with water, and then placed between blotters and weighted down so it will not curl when drying. While this may remove severe buckling it can leave new water damage. While wet the card also becomes very soft and all printed surfaces can be damaged very easily. Soaking cannot be done with hand colored cards without removing the color and staining the paper. Paper that has buckled from exposure to water will never completely regain its former appearance.

It is best to store and handle cards in an environment free of any possibilities of exposure to liquids. Humidity can be much more difficult to control. Environments that are either to damp or dry can harm postcards and speed up other deteriorating factors, and great fluctuations between the two are even more harmful. If possible it is advisable to store cards where humidity remains between 30 to 40%.

If postcards are to be stored within a container the addition of desiccant packets of silicon gel can absorb small amounts of moisture and keep humidity at a more constant level. Desiccants can often be heated and reused extending their life.


Heat

When heat is added to a chemical reaction it acts as a catalyst and will speed it up. Likewise when heat is added to a postcard it will speed up any processes that are currently aging and damaging the card. If moisture is added to the mix deterioration is sped up even further and new problems of infestation by mold or insects may arise.

Heat is a contributing factor to damage and its ability to be repaired will depend on the problem it is coupled with.

Postcards can be protected from heat damage by the extent the temperature of the environment they are stored in can be controlled. The perfect temperature to store cards in is between 60 and 70 degrees Fahrenheit. At the very least postcards should be stored in areas that are the least prone to overheating by natural or manmade sources.


Flaking

When changing temperatures and humidity expand and contract different areas of a postcard at different rates the more brittle areas can crack. Varnishes, thick layers of ink as found on chromolithographs, and the emulsions of real photo postcards are most susceptible to this problem. If the bonds between these materials and the paper are weak sections of the image can flake off a card exposing the paper underneath. This is especially true if the card is pressed against another surface that is more attractive to these materials than the original paper. Not only can the loss of surface damaged one card, but it can hurt another if its lost surface peemanently bonds to a second card.

Areas of a card that have been lost to flaking are gone for good.

While flaking cannot be repaired steps can be taken to help prevent additional loss of surface of which these cards a prone to. They must be stored rigidly and with as little handling as possible to avoid more cracking and surface abrasion. Controlled humidity is even more essential here as cards with cracks and missing flakes are even more susceptible to moisture damage.


Mold

While mold can severely attack and destroy an entire postcard that has remained wet for an extended period of time, most mold damage will appear in the form of small dark or reddish spots (foxing). When a postcard retains any moisture mold can be attracted to certain impurities either leftover in the paper itself from the manufacturing process, or to substances on the paper surface left there through handling. As long as the paper has continued exposure to moisture the mold will continue to grow and create further damage. These small spots that appear on postcards may not always be mold as they can also be caused by iron residue in the paper.

Mold can sometimes be removed from paper by soaking it in water until the spots float off from the surface with a little agitation and stroking with a soft brush. This however is a very dangerous procedure for postcards for the potential for water damage can be greater than the mold itself. When wet the printed surface of the postcard is extremely delicate and can be easily damaged by touch. Unless dried flat under pressure the postcard will most likely buckle. This will also retard the drying process, which may give new molds a chance to grow. Once wet a card will never look as good as it once did. This process cannot be used with hand colored cards. If the problem is iron residue or oxidation mistaken for mold, soaking will have no effect.

Chemicals such as peroxide bleach, denatured alcohol, or even lemon juice have been used to kill mold and lighten spots on paper. The danger here lies in that these substances may alter the color of the paper itself and become as visually intrusive as the mold spot. While this procedure can stop mold from spreading so can less invasive measures as dry storage.

While plastic coverings are a good way to generally protect postcards, moisture can condensate on their surface in contact with the card and create an inviting environment for the growth of mold. However if cards are stored in a relatively dry environment mold will not grow and any existing mold spots will not grow larger.


Insects

While the celulose in cards may be attractive to snails and slugs they are not a common houshold pest. It is the lignin in paper that can provide food for a variety of insects including silverfish, mites, book lice and worms. Postcards even seem to be a popular food among some roaches, termites, and moths. While insects are generally attracted to poorer quality papers because of their higher lignin content all postcards remain susceptible to their dietary interest. The gelatin in the emulsion of real photo postcards is also very attractive delicacy to a variety of pests. Insect damage may appear as tapered irregular shaped depressions on either side of the card with hard edges. In some cases these eaten areas may create holes completely through the card.

Insect damage cannot be repaired.

Storing postcards in a proper environment may keep insects away. While insects like the same dark and cool environment that is also good for postcards, they also generally prefer an environment that is damp. Cards should be stored in a relatively dry environment and away from other paper products that may attract insects. While a clean environment is a good added precaution, pests may be carried in or moved around unknowingly on a variety of paper products.


Postmarks

The cancelation of postage by a heavy hand stamp can embosses a postcard damaging the image. It is also common to find a cancelation stamped across the image side of the card by mistake.

The ink used by the Post Office Department was made so it could not be removed from a canceled stamp. The same holds true when attempting to remove it from a postcard’s image. The printed ink of the picture will come off a card before the ink of a cancel. If necessary an electric eraser that can provide high pinpoint abrasion used with a metal erasing stencil can isolate a specific mark for removal. But even this will only work on very light marks and the removal process can very easily cause further damage to the card.

Cancelation marks on the front of postcards seem to be as prevalent today as they were a hundred years ago and are probably not going to go away. It is best to view the cancel as part of that card’s history, and if it is found to be too troubling, the card should not be purchased.


Tarnishing

As photographs age the processing residue or silver, migrating out from the image can form a very noticeable surface crust of varying colors. Though found on almost all silver bromide images and developed out prints, it can occur in any silver based images with an organic emulsion.

Tarnishing is part of the internal aging chemistry of certain photographs and it cannot be reversed.

It is best to keep ones hands off of a photographs surface for any oily residue left behind will exasperate tarnishing eventually creating pitting and dark smudges or fingerprints that cannot be removed.


Foreign Objects

Postcards can suffer from indentations caused by being bundled together by rubber bands or paper clips. Paper’s organic nature will cause its fibers to slowly reshape around areas of applied pressure in a similar manner to the way decorative embossings are created. In addition as rubber bands age they will loose their elasticity and the chemicals within it may cause the rubber to bond with the cards surface.

Any object that applies pressure to a card should be removed to prevent further damage. Fresh indentations may disappear over time as the paper breaths but in all likelihood some mark will always remain behind. Old rubber bands that are stuck to a card can often be faked of a card’s back with little problem and the remaining material carefully scraped off. There may however be residue that has soaked into the papers fibers and will continue to do damage. The ink on a postcard’s front will often bond with the rubber band and flake off with it if removed. The choice here is to accept some damage or take it to a conservator for professional repair.

It is easy to avoid these problems by simply keeping foreign materials away from postcards. Even when in plastic sleeves the pressure from a rubber band or clips can damage a fragile card causing indentations or tears.