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Enclosure for Broken Glass Plate Negatives

Purpose

To safeguard fragments of broken glass plate negatives, the shards should be kept in a special, custom-made, sink mat housing. The goal of these sink mats is to store the broken glass horizontally, with all the fragments in the same housing, while keeping them out of direct contact with one another. Future repairs, therefore, are less difficult because the edges of the shards are not allowed to abrade against one another. The flip-open front border and the additional plastic support allows one to remove and examine the glass plates with minimal manipulation.

 

Author(s)

Conservation Center for
Art and Historic Artifacts
264 South 23rd Street
Philadelphia, PA 19103 USA
Tel (215) 545-0613
Fax (215) 735-9313

Illustration: Alexia S. Scott

Publication: 1992

 

Description

The housing is constructed of pH neutral, rag or corrugated board. It consists of a flat base and four side strips which create the sink mat walls. A sheet of polymethylmethacrylate is used to support the glass plate. The front strip is hinged and drops forward to permit easy access to the plate. A protective lid is hinged to the upper edge of the sink mat (Fig. 1).


Materials Tools Supplies

  • Cotton gloves, lintless
  • Double-coated tape or polyvinyl acetate emulsion adhesive
  • pH neutral linen tape, water activated adhesive
  • pH neutral paper board or corrugated paper board
  • Polyester film
  • Polymethylmethacrylate sheet,1/8in


Construction

  1. Cut a base and top to a standard size that is at least two inches larger than the object on every side.
  2. Cut a piece of polymethylmethacrylate sheet to a size large enough to support the broken plate when it is laid out flat, with the glass pieces slightly separated. Leave two additional inches at the top and bottom.
  3. Construct the sink mat walls from strips of the same board material used for the base.
  4. Adhere the two sides of the walls to the base board with double-coated tape.
  5. Hinge the front wall section onto the outer edge of the mat with water activated linen tape, so that it folds outward providing a drop front (Fig.1).
  6. Cut a sheet of polyester film to the width of the ridged plastic support, and approximately 2in longer on the top and the bottom.
  7. Place the polyester film under the ridged plastic sheet, so that the entire support can be easily lifted out (Fig. 2).
  8. Wearing cotton gloves, place the glass shards into the structure onto the ridged plastic sheet with the emulsion side up. All the outer edges should be flush with the mat walls so that spaces are left between all fragmented edges.
  9. To insure that the fragment edges do not come into contact with one another, insert small squares of board at strategic points between the glass shards. These can be adhered to the paper base with a polyvinyl acetate adhesive, or double-coated adhesive tape. Care should be taken that none of the adhesive comes into contact with the negative.
  10. Hinge the pre-cut lid to the upper edge of the top border with water activated linen tape.
  11. Store the housing horizontally in a standard sized clamshell box (See Jensen and Tweedy, “Phased Box Construction,” this volume).


Comments

White cotton gloves should be worn at all times when handling the glass plates. These are necessary to keep the plates free from irreversible damage caused by fingerprints. Note, however, that the gloves provide less grip and special care must be exercised in manipulating the glass.

Repair of broken glass plate negatives is still at the experimental stage. Research is underway to discover an adhesive and method of adhesive application best suited to the reservation needs of thee objects. Until the long term effects of the adhesives on the photographic binder and final image materials better quantified, it is advised that broken plates be stored as described above.

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