Originally Posted by SkipA
Mylar D was replaced by Dupont Archival Polyester--it's really pretty much the same thing, although there are different grades of polyester. At any rate, the best plastic sleeves are made from *uncoated* materials---which is very hard to find in most sleeving. Mylar D, Dupont Archival Polyester or Melinex 516 (all pretty much the same product) is used mostly for filing documents, postcards, currency, negatives etc. It's used for preservation encapsulation and mountmaking as well.
The best sleeves out of this material are the "interleaving" type--which is just a fold in half (good if youi access the file alot), with 3 open sides, and a "locking edge" type (good for long term, I prefer these). With Mylar D, it's possible to sonic weld or heat form seams, but mostly this is used in encapsulation. Polypropylene about a third of the cost, and comes in the same types of configurations--but needs to be uncoated as well. Mylar D can have some static problems and is very tough. Hard to tear or cut.
Polyethylene is the cheapest of the three "safe" plastics. It comes in two grades--low density and high. The high density is the best of the two, but is a translucent type material similar to what minilabs use in sleeving machines. There's only one consumer product as far as I know, and it's the HD Polychron sleeve that LI markets. This is supposedly a very safe longterm material, but you can't view it on a light box or contact through it.
Low density polyethylene can have some problems--mainly from the slip agents that are added to the plastic as they form those notebook pages and other configurations.
Glassiene and acetate used to be popular but have fallen out of favor now. Glassiene is still used in some forms as an interleaving or packing material though. Acetate suffers the same problem as film bases--it falls apart eventually. The archives near where I work used it for years and these sleeves just are useless in their old-age...glassiene can cause some severe staining problems and the adhesive seams can stain as well.
It can be confusing with all the products to choose from, but here's what we do at the museum where I work:
Modern negs & chromes: Mylar D or polypropylene fold-lock type sleeves. For color transp.--use unbuffered, acid & lignin free envelope. (look for products that pass the PAT). B/W--use same sleeve, but a buffered envelope.
The film is stored in separate file cabinets--for 4x5 we use Russ Bassett or Visuflex media cabinets. These are designed for storing film--each will hold 900 4x5s, they either stack or come as floor units--very well made, baked enamel steel cabinets. You can get these from Gaylord, or other library supply vendors. We use these for 35mm and 120 roll film as well--each drawer is about 4.5 inches tall. They hold roughly 150-200 rolls of film depending on what type of envelopes you use. Slides are stored in hanging Permasaf or some Saf-t-stor files in file cabinets. Each slide is kept in a single Mylar D sleeve to keep it off the plastic.
For 8x10--we use flip top vertical Hollinger boxes (metal edge boxes). The negs go into paper (PAT) folders and are stored in small numbers to a box, vertically with partitions to keep them upright & pressure off. This is probably the best way to store negs/chromes outside of a cabinet. For older negs and plates--use 4-flap paper enclosures. No plastic.
Some other companies besides LI to look at: Gaylord Bros., Hollinger, Talas, University Products, Metal Edge, Archival Methods, Conservation Resources Int'l.
fwiw--CRI has some of the best boxes and paper enclosures, but most of these companies offer essentially the same products and are used interchangeably as long as they pass the specs.
Here's a link to the IPI. Check out the Climate Notebook and the Media Storage Guide, as well as the Preservation Calculator:
NEDCC guide to storage materials:
Hope this helps somewhat & isn't too confusing. You can also get some good advice from some vendors like Hollinger, Light Impressions, Gaylord and University Products to name a few.
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