TSLAC Conservation

Housing a Glass Plate Negative


Though our conservation lab at TSLAC focuses primarily on books and paper, we also care for the non-paper-based archival items found in our collections.  This month, we created a housing for an undated photographic glass plate negative from the Sam Houston Regional Library and Research Center in Liberty, TX.

A glass plate negative consists of photographic emulsion cast on a glass plate.  The negative image on the plate is later developed into a photographic print.  Glass makes these negatives very fragile.  When they break, their fractured edges begin to abrade one other, causing more damage to the glass and the media.

Broken glass plate negative in modified sink mat.

Our housing is based on a design from the National Archives.  The broken negative is stored in a covered sink mat for protection.  Small spacers separate the broken pieces to minimize abrasion.  The mat is stored flat in a box with a warning label regarding careful handling.

Detail of spacers separating broken fragments.

The outer mat edges are hinged, allowing the item to be removed from its housing as needed.  However, future removal should be rare, since the image was scanned before treatment.

Scanned image from glass plate negative.