In September, TSLAC Conservation worked on the Map Showing the Beaumont – Sour Lake – Saratoga Oil Fields of Texas (nd) from the Sam Houston Regional Library and Research Center in Liberty, TX. This 60 cm x 45.5 cm map features printer’s ink on machine-made, wove paper. Adhesive staining, tears, and losses presented challenges for its upcoming exhibit.
Map before treatment – Recto, spectral light
Map after treatment – Stain reduction and fills
A sticker-style label attached to the back of the map had caused pronounced staining on the front, upper right corner. Solvent testing revealed that a mixture of acetone, toluene, and xylene was most effective on the stain, likely indicating an acrylic-based adhesive. Successive poultices of the solvent mixture with Fuller’s earth provided some stain reduction, but better results were achieved by rolling with a solvent-dampened swab. Care was taken in applying the solvent mixture over a ball-point pen annotation that was revealed beneath the removed label. This ink proved surprisingly stable in the solvent mixture.
Adhesive staining and ball-point pen ink were revealed beneath the removed label.
The map was washed and deacidified on wet blotter to reduce overall staining and localized tidelines. Fills were constructed of handmade, Ruscombe Mill paper toned with water-thinned acrylic paint. Fills were cut to shape, pared along their edges for a smooth seam, and adhered with wheat starch paste. Extensive edge tears were then mended with NARA heat-set tissue.
Toned, shaped fills await final trimming.
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.