^
collecting supplies

"Archival quality" generally describes products and materials that are safe for long-term storage and display of paper and collectibles. Art conservation specialists, museum professionals and product suppliers use the following standards and definitions for storage products.

The best-quality plastic storage products use a special type of polyester film, commonly called Mylar, or "archival polyester". You can also store paper collectibles and documents in less expensive Poly storage products. This term often refers to higher quality polypropylene (PP), but is also used for polyethylene ( PE). A list of storage product brand names identifies companies that make mylar and poly products.

Mylar is crystal-clear, very strong, and performs far better than other types of plastic as a barrier against dust, pollution, water vapor and oily fingers. The Library of Congress will use only polyester products (such as Mylar) that "must not contain any plasticizer, surface coatings, UV inhibitors, or absorbents, and be guaranteed to be non-yellowing with natural aging.

Thick, 4-5 mil. mylar storage products are the best for long-term storage of a valuable collection. Economical, 1-2 mil. mylar is used to best display game cards, matchbook covers, postcards and photographs at flea markets and conventions.

Low Density Polypropylene (PP) and Polyethylene (LDPE) are less expensive than mylar. Storage products made from polypropylene are strong, non-yellowing and less prone to scratching. Clear polyethylene is the least expensive material, acceptable for short-term storage of collectables.

Avoid direct contact between your collection and any products that contain PVC - commonly known as Vinyl - including some erasers, 3-ring binders, bubble wrap and adhesive tapes. The ink from artwork and photocopies can 'transfer' onto the surface of (for example) the inside pocket of a vinyl 3-ring binder.

Most important - keep paper and collectibles out of direct sunlight or in an acid-free box. Avoid keeping your collection in the basement or attic where humidity, insects and extreme temperatures can cause damage.

Plastics Glossary

cellophane

• crystal-clear
• organic based alternative to polypropylene
• many sizes
• brittle
• grease, oil & moisture resistant
• approved for food use
• heat sealable

polyester - any of a group of polymers that consist basically of repeated units of an ester, used especially in making fibers and sheets of plastic film.

Polyethylene Terephthalate (PET) in europe (PETE) is one form of polyester that can be completely recycled into thousands of new products (refer to the "chasing arrows" logo number one).

Uses: soda bottles, leisure suits, x-ray film, video tape and packaging. Recycled into carpet and fiberfill insulation for ski jackets.

"Mylar D" and "Melinex 516" are trade names for a special way to make a crystal-clear and strong form of PET plastic, used for true archival-quality storage and conservation products. Mylar is "bi-axially extruded polyester film", which aligns the "chains" of molten plastic both vertically and horizontally, similar to the 'grain' in a sheet of paper.

• Best plastic storage for a valuable collection.
• long-term protection for paper (100 years).
• Mandatory for archival conservation
• Crystal clear and very strong
• very effective barrier against air & moisture
• resistant to grease, oil, heat, oxidation
• chemically inert & non-yellowing
• will not shrink - "dimensionally stable"
• naturally UV resistant
• Can be produced without harmful additives
• generates static electricity which attracts dust
• Mylar is more expensive than "Poly" products

polyethylene

• high density polyethylene (HDPE)
  
  • milky white or colored with pigments, waxy feeling.
  • uses: milk cartons, photographic film canisters, cereal box liners, printed shopping bags

• low density polyethylene (LDPE)
  
  • Inexpensive plastic for short-term storage.
  • Easy to blend & process
  • low melting point
  • more clarity than polypropylene, but -
  • Least rigid material (very flexible)
  • low tensile strength
  • scratches easily (low hardness)
  • uses: clear bags for dry cleaning, bread and frozen foods; squeeze bottles, insulation.

polypropylene (PP) polymers of propylene

• Quality plastic storage products.
• Lightweight but strong
• non-yellowing
• resistant to chemicals and heat
• crisper than polyethylene (less flexible)
• can be "oriented" (like mylar) for strength & stiffness
• less static than mylar
• less protection from air and moisture than mylar
• The best storage products are made without adding vinyl (PVC), plasticizer, softeners or surface treatments.

polystyrene (PS)

• clear, hard and brittle
• uses: Compact Disk "gem" cases, toys, house wares, and luggage. Foam cups, plates, egg cartons and insulation.
• used for storage boxes

"vinyl" (V) or polyvinyl chloride (PVC)

• used for short-term business document storage
• Not suitable for archival storage purposes
• good transparency (clarity)
• chemical and weather resistant
• scratch-proof
• "all PVC polymers are degraded by light and heat, hydrogen chloride is eliminated and oxidation occurs"
• retains water (8%)
• "chemicals used to make this type of plastic can react with water vapor to form hydrochloric acid and quickly damage a paper collection."
• uses: "leatherette" fabric, gloves, flying discs, carpet & flooring, pipes, exterior siding, 3-ring binders, bubble wrap.
• not recommended for use with silver.

references:

Library of Congress for archival product Specifications, and a good FAQ about preservation of works of art on paper.

Caring for your Documents and Works of Art on Paper from The American Institute for Conservation of Historic & Artistic Works. HTML version in English, and in Spanish or download the colorful PDF file (Adobe Acrobat).

The American Plastics Council is a great source of information for "end-users", in simple language. Educational material includes the very informative Introduction to Plastics: Background Information for Teachers. Read the document in your browser window [HTML format] or download the large 1.9 MB [PDF format] for Adobe Acrobat. This illustrated document includes a chapter about "Common Plastic Resins Used in Packaging" with the best description of the 7 different plastics represented by the "chasing arrow" recycling symbols. Many other resources on the general history of plastics, a simple chart of plastic properties and applications, and a good historical article from Newsweek Magazine.

More history of plastics from the society of the plastics industry and technical definitions of plastic resins. Download small 11KB PDF files for each of the seven recycling symbols: (PET) (HDPE) (V) (LDPE) (PP) (PS) (OTHER)

Mylar® and Melinex® polyester film, only by DuPont Teijin Films. (go to Products and Technology tab and find Mylar in the left column . Compete technical data - "Celebrating 50 years")

A beautiful splash screen with dots from NAPCOR, with specific information about PET and free samples.

Please email us regarding errors or omissions, as facts and opinions presented on this page cannot be guaranteed for accuracy.