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Finding Archival Supplies for Preservation

What materials should be used to store or display collections?

Containers, supports, and mounts should be made from materials that are inert, chemically stable, and durable. Using the wrong type of material to store or display collections can cause physical or chemical damage like discoloration, yellowing, cracks, or breaks.

What do the terms “archival quality,” “conservation quality,” and “preservation quality” mean?

These terms have been used over the years to imply that materials meet standard museum preservation requirements. Some manufacturers or suppliers may use these terms loosely, and apply them to materials that are not inert or chemically stable. For this reason, it is best not to rely on these terms but to use specific characteristics, as described below.

Why is chemical stability important?

Chemically unstable materials break down over time and can release harmful byproducts as they do so. Some of the deterioration that items in storage suffer is caused by the acids and other harmful substances in the containers, supports, and mounts that are used to protect them. These harmful substances migrate from storage materials into the items, causing such problems as discoloration, corrosion, and embrittlement.

To avoid these problems, it is essential for all storage materials to be chemically stable—to not generate any harmful substances. If this is not possible, a chemically stable barrier can be used between the storage material and the item. For example, an acidic cardboard tube can be covered with a stable material such as polyester film, which acts as a protective barrier between the acids in the tube and the item rolled on it.

Paper-based storage materials

Paper-based storage materials include folders, envelopes, tissue paper, mounting boards, and corrugated board for boxes. Not all paper-based materials are safe for the preservation of collections. Wood-pulp paper can become acidic over time as the chemical component lignin degrades. This can result in acid burns to your collections. Paper materials made of 100 percent cotton or linen are safe to use, but paper materials made from wood-pulp must be chemically purified to remove lignin before they can be safely used. Such materials are commonly described as acid-free. It is important to be aware that not all paper-based materials are acid-free. Standard museum preservation practice maintains, however, that only acid-free materials should be used.

Why is pH important?

Knowing the pH of paper-based storage materials will tell you whether they are acid-free. The acidity and alkalinity of paper and paper-based materials are expressed by pH, a measurement on a scale of zero through fourteen. Seven is the neutral point, with measurements under seven indicating increasingly acidic, and over seven indicating increasingly alkaline conditions. Although the recommendation varies for what an ideal pH for storage enclosures should be, depending on the item to be stored, a pH of 7.0 through 8.5 is a good general range.

It is advisable to measure the pH of purchased storage materials to ensure that they are acid-free (pH over 7), because sometimes materials do not meet their advertised levels. There are several methods for measuring pH. The simplest is the use of a pH detector pencil or pen, which indicates the surface pH of the material being tested (never to be used on a cultural object). This method is suitable for most situations. These pencils and pens are relatively inexpensive and readily available from conservation suppliers. A more specific pH reading can be obtained by using pH indicators strips. The most accurate readings are those provided by pH meters. These latter two methods are used primarily by museums.

What is an alkaline reserve?

Some paper-based storage materials contain a buffering agent, such as calcium carbonate, added during manufacture. This buffering agent is referred to as an alkaline reserve. The alkaline buffer neutralizes acids as they form in the storage materials and helps keep the materials acid-free long-term. Over time, however, the buffering agent may eventually be depleted.

Should buffered or unbuffered materials be used?

Buffered materials are appropriate for storing some items but not others, and you must know which to use. Museums keep supplies of both buffered and unbuffered materials and use whichever is appropriate for the item being stored. It is, however, expensive to keep both types of supplies on hand. Also, it is impossible to distinguish between them visually, so they must be clearly marked. The easier and safer approach for most people is to use acid-free unbuffered materials for everything.

What are molecular traps?

Some types of storage material incorporates molecular traps to provide added protection from gaseous pollutants. Molecular traps, such as activated carbon or natural or synthetic zeolites, capture and retain pollutants. These are most suitable for storage materials that will be used in highly polluted areas or for items that are particularly sensitive to pollutants. Storage materials that contain molecular traps are available as paper or board and are sold under the trade name of MicroChamber.


Items should be stored only in containers that are sufficiently durable to protect them. If containers are not sturdy, the items they contain may become distorted or broken, or the container itself may become damaged or even fall apart. Needlessly strong storage containers may also present problems, adding unnecessary weight and bulk that can lead to handling and spatial difficulties.

Are plastics safe to use?

Some plastics are chemically unstable and produce by-products as they deteriorate that accelerate the breakdown of many materials, and can even be hazardous to human health. These should always be avoided, even though using them is tempting because they are easily obtained and inexpensive. Three types of plastic meet preservation standards. These are polypropylene, polyethylene, and polyester. These plastics come in many forms with different characteristics—planks or foam, rolls or sheets, hard or soft, thick or thin, opaque or transparent—and are sold under different trade names.

Polyvinyl chloride (PVC) should not be used in any form—not as sheeting, a photograph sleeve, or a tube—because of the damaging by-products it emits. The same is true of bubble-pack; do not use it, because of possible coatings, physical damage, or harmful by-products. Avoid polyurethane, like that commonly found in seat cushions; it turns to powder as it ages and gives off damaging by-products. Finally, do not use polystyrene, as this has a tendency to become brittle and yellow as compared to other acceptable plastics. Generally it is important to determine that the plastic materials you use for long-term storage are one of the three safe types.


The following information is provided only to assist those seeking to care for their personal collections. Inclusion of a company name in this list does not in any way imply endorsement by the Minnesota Historical Society.

Archival-quality storage materials can be found in many places. The following online suppliers provide a range of archival storage and display materials.

Conservation Resources International LLC
7350-A Lockport Place
Lorton, Virginia 22079

Gaylord Archival
PO Box 4901
Syracuse, NY 13221

Hollinger Metal Edge
9401 Northeast Drive
Fredericksburg, VA 22408

Light Impressions
100 Carlson Rd
Rochester NY 14610

330 Morgan Ave
Brooklyn, NY 11211

University Products
517 Main Street
Holyoke, MA 01040

If you have any questions about archival storage materials, please contact conservationhelp@mnhs.org.

From Caring for American Indian Objects: A Practical and Cultural Guide. Sherelyn Ogden, ed. St. Paul: Minnesota Historical Society Press; 2004. Updated 2022, Megan Narvey.