Preservation

How Do I House Glass Plate Negatives?

Housing Glass Plate Negatives at the National Archives and Records Administration

Glass Plate Handling Procedures

  • Ensure that you are working on a clean, flat, dry surface, free of any debris.
  • Wear non-vinyl plastic gloves when handling the plates: Latex or Nitrile, for example. Cotton can be slippery when handling glass and may snag flaking emulsion.
  • Handle plates by two opposite edges. Never hold them by one edge, or the corners
  • Place glass plates emulsion side up when you lay them flat on a surface.
  • Never place any pressure on the plate: do not press, lean, or write on top of it.
  • Never stack the plates while you are working with them. Only work with one at a time
  • Label your sleeves before placing the plates into them.
  • Duplicate high use glass plates. The emulsion is fragile, and even plates in good condition will be damaged from regular use.

Glass plates that are not broken or flaking

  1. House glass plates individually in loosely-fitting, buffered paper sleeves with side seams. Place glass plates in the sleeves with the emulsion side away from the seams, as they are easily abraded by insertion/removal from the envelopes. Seam adhesives also may be a source of image deterioration over time if left in contact with the emulsion.
  2. Store the plates vertically, on the long edge, in document boxes. Interleave every inch with corrugated board to support the plates. For plates 8 x 10" and smaller, half-size boxes are preferred as the plates can be heavy. If the box is under-filled, place sheets of corrugated board (cut same size as the plates) in the front and back of the box to support the plates snugly in the center.
  3. Use oversized legal boxes for plates over 10 x 12". These can be very heavy, and SHOULD ONLY BE PARTIALLY FILLED with glass plates. Corrugated sheets should be placed at the FRONT AND BACK of each box to fill out the box, to support the plates and to ensure that the weight is balanced. Use full width boxes for these larger sizes due to their greater stability and reduced risk of tipping.
  4. Place a sheet of corrugated board in the bottom of the box if the plates are to be shipped for duplication. See the answer to How do I move glass plate negatives? for guidance on transporting/shipping glass plates for specific padding/packing recommendations. Otherwise, for routine storage, no extra padding (or cushioned box) is needed.
  5. Boxes may be stacked two high, no more.
  6. Label boxes clearly with CAUTION, FRAGILE, GLASS, and HEAVY signs.

Intact glass plates with flaking emulsion

The extent of flaking, use, and value of the glass plate will dictate the housing option chosen for plates with flaking emulsion.

  1. Minor Flaking: a few small edge losses, and glass chipping at the edges where the emulsion appears stable and secure at the loss site ( no lifting at the edges of the loss, no flaps of emulsion).

    NARA practice is to house such plates in sleeves, as described above, with added handling note: Flaking edges, remove/insert into envelope with care.

    Continue as described above.

  2. Significant flaking: flaking edges with hanging flaps which could be torn off; cracking overall with blind cleavage at the interior (looking like a dry mudflat).

    Duplicate flaking plates, and avoid handling the original plates after duplication. House these plates in four-flap enclosures, and store them vertically as described above. Very high value plates with extensive flaking/cleavage should be sink-matted and stored flat. In either case, add a handling note: Flaking glass plate: handle with extreme caution. Use duplicate copy.

Broken Plates

  1. Sandwich the broken pieces between two sheets of buffered board.

  2. Place the sandwich into a four-flap enclosure.

  3. Several sandwiches can be stacked flat no more than 5 deep in a shallow box labeled BROKEN GLASS-STORE AND CARRY HORIZONTALLY, and store flat.

Enclosure Materials

The paper stock used in the enclosures and storage boxes should be of high quality, lignin-free, sulfur-free, alum-free, pH 7-8.5 paper which meets the requirements of the American National Standards Institute (ANSI) IT 9.2 Photographic Enclosures (now ISO 18902) which includes the Photographic Activity Test. ANSI IT9.17 Photographic Plate-Storage (ISO 3897) provides recommendations on the storage of glass plates.

NARA recommends buffered paper stock for the storage of all photographic materials. The degradation of all paper products over time means that the use of non-buffered, neutral paper stock results in short order in an acidic folder that becomes increasingly acidic. Recent research has shown that the only hazard to alkaline-sensitive photographs is in the event of prolonged exposure to water. Since buffered paper has been shown over time to drop in pH, this is only an issue for the first 10 years or so of the package's lifetime, after which the enclosure is neutral pH or slightly acidic.


See the answer to How do I move glass plate negatives? for guidance on moving glass plate negatives.

[note]
Rev 6/18/01
Sarah S. Wagner, Senior Photograph Conservator and
Miranda Martin, National Preservation Program Officer
Preservation Programs
National Archives and Records Administration

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