There are some really simple concepts to embrace without getting deep into the weeds when considering preservation. I will address the preservation of collectible certificates in particular which, for the most part, are simply printed paper. Obviously, some of the paper used for security printing was more resilient and much tougher than ordinary paper. I will not address preservation methods for artwork and photographs because they are inherently more delicate than most certificates and require added attention and more specialized preservation methods.

Where to find information

Library of Congress web page
Library of Congress page on Preservation — Tremendous potential reduced to little more than a collection of FAQs.

The Library of Congress deals more with issues of preservation than any other institution in the United States. The archivists who work there have tremendous amounts of scientific information at their fingertips. The library itself, however, divulges almost nothing on its web site. I hate getting crosswise with the L.O.C., but I find its web site seriously lacking. Isolated pages on its site sound enticing, but when I get there, I find no solid information, It is like following detour signs everywhere, all leading into dead ends. If information is there, then someone needs to re-work the site from top to bottom to make it findable and usable. If someone knows the tricks for getting behind closed doors, PLEASE let me know so I can share with my readers.

Several universities address the issue of preservation much better. I suggest people who want to learn more about paper preservation to start searching the web for information. Do not expect to find anything that expressly discusses the preservation of securities.

The basics

We have a few major considerations:

  • How to keep paper from deteriorating?
  • How to keep colors from fading?
  • How to keep paper from getting folded, torn, or punched?

Trying again to keep things from getting overly complicated, the methodology of preservation is so simple that no self-respecting collector is going to fret over the task:

  • House certificates in envelopes or albums that will protect certificates from folding and tearing.
  • Keep certificates away from water.
  • Keep collections out of basements where broken pipes are possibilities.
  • Keep collections out of attics where summertime heat is an unbearable certainty.
  • Keep certificates away from sunlight in general and ultraviolet light in particular.
  • Keep cool with humidity around 35%.
  • Keep certificates away from any source of acid.

I am guessing that most collectors are already practicing most of these suggestions. If there are any problems, most probably result from sun, humidity, and acid.


Sunlight is problematic because the ultraviolet fraction is hard on paper. It makes paper brittle and promotes the evolution of acid from lignin as it breaks down. As long as collections are housed in folders or binders of some sort, they are already out of direct sunlight. However, if they are kept in rooms with open drapes and curtains, then they are being exposed to indirect sunlight. Collectors can do their certificates a favor simply by moving them to drawers, closets, or storerooms that stay closed most of the time. Boxes are good, but only if they are acid-free and preferably slightly alkaline. That rules out Bankers Boxes and ordinary cardboard. (More on this subject later.)


Certificates are like Goldilocks; they like humidity that is neither too wet nor too dry. Both of these cases are hard to accommodate in the arid West and the soggy South. If collectors live in these too extremes, they already know. They don't need me telling them how to spend money trying to solve their environmental problems. I've lived in both environments and know the smell of mildew as well as the feel of itchy dry skin. The trick, if attainable, is to store certificates in a moderate humidity somewhere between 15% and 65%. Below 20%, paper is more prone to separation when folded. Mold growth becomes problematic with routine storage above 55%. An "ideal" of 35% may or may not be economically attainable.


1986 thesaurus printed on wood pulp paper showing acid deterioration.

Dealing with acid is, in my experience, the most difficult of paper preservation procedures to deal with. It does not require a degree in chemistry, but it does need real-life examples in order to wrap one's head around the problem.

Here is an example from a paperback thesaurus that I bought in 1986. It has never been exposed to direct sunlight, but it has been on bookshelves in sunny rooms in Colorado. Humidity has been climbing in the west suburban areas of Denver over the last several decades. but still averages around 30% to 40%. Note how the center of the page looks much better than the outside edges.

What we're looking at is paper deterioration caused by acid being liberated from the wood pulp paper. Some discoloration is possibly attributable to atmospheric sulfur and nitrogen oxides, but the majority is from the breakdown of lignin in the short paper fibers that make the paper so flexible. I could have shown radically worse examples of orangish and brittle newspapers from the 1940s, but I thought you would think I faked them.

Lignin comprises the tough, woody cells in trees that give them strength. As the cells slowly break down in the presence of oxygen and humidity, they release acid. Even cellulose generates several types of acids. The weird thing about these acids, and the most difficult to find examples of, is the habit of acid migrating from source paper to other paper stored nearby.

Acid migration is the problem that certificate collectors need to come to grips with.

Wood pulp paper was used in a few instances as early as 1765. My experience with newspapers suggests that usage of wood pulp paper really took off in a big way in the United States in the 1870s. Some newspapers from that period are on the verge of total destruction. While generic certificates were often printed on wood pulp paper, most are still in fairly good shape.

Top-tier printers like American Bank Note Company and others used only the best quality rag paper for their securities. Good cotton rag paper can last easily for several centuries. One of my correspondents sent me a dictionary printed in Massachusetts in 1806 and its pages are as supple as any of the ABNCo certificates printed eighty years later. On the other hand, I have a few generic certificates printed in the early 1900s that I will not handle because of fear of breaking off pieces.

It appears that certificates in my collection with the most yellowing or browning date from 1897 to about 1907. It is not that they are in bad shape at all, BUT they should probably not be stored with any of the certificates printed on rag paper.

Data is tough to find, let alone confirm with testing, but sealing wood pulp certificates away from the open air might promote deterioration. If true, then even keeping wood pulp certificates in the same holder or envelope as rag certificates is probably not a good idea. A potential solution is to put wood pulp certificates in Mylar/Melinex holders with a piece of buffered paper that is slightly alkaline.

Moreover, if certificates are currently stored in Bankers' Boxes or cardboard boxes, it would be wise to spend the money and transfer them to special buffered document storage boxes available from several of the companies listed below.

Holders and folders

The pros agree that storage of paper documents in polyester (Mylar, Melinex) holders is a good idea. They are inert and offer support for paper documents. Polypropylene and polyethylene are also okay, but the plastics, by themselves, don't offer support. Polyester holders are a bit pricey, but can be acquired in sizes appropriate for most stocks and bonds. Collectors will need to choose between holders welded on two sides or three sides.

Several preservation specialists sell numerous sizes of archival quality boxes that are excellent for holding polyester holders with certificates inside. The ideal box seems to be one that is acid-free, lignin-free and buffered to a pH of 8.0 to 9.5 (slightly alkaline.)

14 x 17 Itoya ProFolio
14" x 17" Itoya Art ProFolio opened to show the ability to hold 96 regular-size stock certificates

Also available are portfolios that are much more handy for viewing certificates. Manufactured by Itoya under the product name Art ProFolio, these portfolios contain 24 polypropylene pages separated into a front and back by a black (supposedly) acid-free divider. The best sizes for certificate collectors are:

  • 11"x14" — best for holding up to 48 average stock certificates
  • 14"x17" — best for holding up to 48 average bonds, or up to 96 stock certificates (as shown)
  • 18"x24" — best for holding oversized bonds

These portfolios are available from George LaBarre Galleries, art supply stores and elsewhere. Itoya used to make a 14"x11" (landscape) folder that was even better for stock certificates, but Itoya pulled the line several years ago. As late as 2020, I was able to find a few of those folders on the web.


Here are a few of the sites that sell archival materials.

Do you really needed buffered, acid-free containers and boxes?

Instead of making any kind of ill-informed recommendation, let me show you a little experiment I conducted about a decade ago. First, a tiny bit of science is necessary.

"pH" is a measurement of acidity and alkalinity. "pH' stands for "potential hydrogen," which is a measurement of how active hydrogen ions are. Pure water has a pH of 7, which means it is neutral — neither acidic or alkaline. A measurement of 1 would be highly acidic and 14 would be highly alkaline. The pH scale is logarithmic, meaning that an acid of pH 5 would be ten times more acidic than pH 6. (Lesson finished.)

Archivists have special instruments to measure the acidity of paper, but I don't. I performed this experiment in my kitchen. I wanted to determine which kinds of papers were acidic and which were not. I put drops of water on different types of paper used by stamp, paper money, and certificate collectors. I let the water set a minute or so, and then measured the acid content with pH paper. We're not talking rocket-science here, because I didn't want to pay some lab to do it for me. Consequently, I will never say my results are completely scientific.

white copy paper 6.0
manila folder 5.5
white backing board 5.5
kraft envelope 5.3 to 5.5
white envelope 4.7 to 5.3
black stamp book paper 4.5 to 5.0
glassine envelope 4.5 to 5.0
newspaper 4.5

I realize that the pH values of paper varies among manufacturers. But you can see that all the papers I tested were somewhat acidic. Most importantly, some of the supposedly "best" papers were the most acidic.

Take the "black stamp book paper" listed above. That was paper that came out of several expensive stamp albums. All the pages were acidic. Some were almost as acidic as newsprint. Surprisingly, I found the same thing with glassine envelopes. They are the standard storage envelopes used in the stamp hobby. I contend that neither storage method is safe UNLESS you buy the really good stuff. And the good stuff is expensive.

Buffering acid in your paper

Some conservationists use deacidification solutions to buffer the effects of acid normally found in paper. Some conservationists are strident in their insistence on stopping acid deterioration before it starts.

Perhaps the best known method is the application of a solution containing an alkaline agent, particularly ethoxy magnesium ethyl carbonate. The most famous solution is sold under the brand name "Wei T'O" and is available in a number of different solutions appropriate for different types of preservation needs. See links above to various archival storage companies. I cannot make a recommendation for its use because I have never used it. If you have, I would like to learn of your experiences.