Polyethylene Foam Inserts for Specimen Trays

The storage modification involves lining a tray with 1/4in thick layer of polyethylene microfoam. Tray labels are supported in a vertical position within a polyester film sleeve (Fig. 1).

Figure 1. Improved storage with foam inserts.

This system provides padding to the base of a specimen, restraint from tumbling in response to drawer movement, and a convenient method of supporting tray labels in a highly visible position.

• Fine cell polyethylene foam radiation cross-linked, 1/4in thick
• Folded polyester film sleeves, 3mil
• Hot melt adhesive and glue gun
  
  
  

Liner

1. Cut a rectangular piece of cross-linked polyethylene foam so that it is approximately 1mm wider than the inside width of a tray and of appropriate length to cover the inside front, bottom, and back of the tray.
2. For trays with a width of less than 10cm, press this section of foam into place by hand. The foam will maintain its position as a result of friction with the tray sides.

OR

For larger trays, adhere the foam liner to the base of the tray along lines near the front and the back of the liner. The use of a hot melt adhesive has proven to be convenient and effective and is thought to be safe for geological specimen storage in situations where there is no direct contact between the adhesive and the specimens.

Label holders/protectors

1. Purchase polyester sleeves that are sealed on one side and open on the remaining three to hold and protect tray labels. The size should be slightly narrower than the inside width of the smallest standard tray and as high as the sum of the standard tray label height and the inside tray depth. One size of polyester sleeve will usually suffice for the vast majority of specimens in a collection. The occasional larger or smaller sleeves that might be required can be fashioned by folding and creasing an appropriately sized rectangular piece of polyester film 3mil.
2. Insert tray labels in the polyester sleeves with the top of the label against the seal line.
3. Slip the open end of the sleeve between the foam liner and the back of the specimen tray. This provides good visibility and physical protection for utilitarian labels with little intrinsic value. When historically significant labels are involved, further protective measures might be warranted and the advice of a conservator specializing in paper should be sought.

Additional Specimen Support

Smaller pieces of foam can be used to bolster specimens that have a tendency to topple when drawers are opened or closed. Place one such bolster along the front of the specimen and another along the back. In some cases, such as large, top-heavy specimens, more care in providing support is required. One convenient method of providing a more custom fit support is to:

1. place a second (or more) sheet of polyethylene foam over the base of the tray;
2. rest the specimen on both layers overnight; and
3. cut out the impressed area of the second sheet using a scalpel.

Because most collections employ standard-sized trays, often sized in multiples of one another, it can be convenient and cost effective to have most of the required sizes of foam sheet die-cut by the supplier. Through surveying a sample of the collection, a fairly accurate estimate of required sizes can be determined. In a systematically arranged collection held in approximately three hundred 0.5m3 cabinets, for example, a count of the trays in every tenth cabinet gave a proportion of tray types that reasonably reflected those in the collection as a whole. Request that off-cut material be included in the shipment of die-cut pieces to use for supporting specimens that have a tendency to tumble when the drawers are moved.

A few cautions should be noted:

• Specimens having delicate and sharp crystals protruding from the base are not suited to this storage system since the sharp crystals will penetrate, and embed in the foam. This may result in breakage when specimens are removed. Specimens of this type are better stored using other supporting materials such as polyester batting overlaid with neutral pH tissue paper.
• If trays are over-filled with foam, it can be difficult to position fingers around the specimen to safely remove it; specimen supports of any type should always be designed with ease of safe specimen removal as an important concern.
• This storage method increases the quantity of flammable material, and may increase contamination of specimens in the event of a fire by melting onto them. Consequently, for collections not protected by a fire suppression system, this method may not be advisable.