Recent Advances in the Conservation of the Postmaster General Collection
By Scott W. Devine, Paper Conservator
The Postmaster General (PMG) Collection includes a philatelic collection of postage stamps, die proofs, and other material related to the printing of stamps as well as an art collection. The art collection consists of original artwork, primarily works of art on paper, commissioned by the United States Postal Service (USPS) over the past 75 years for use in the design of US postage stamps. Under an agreement with the USPS, the PMG Collection has been deposited on long term loan to the National Postal Museum. Museum staff are responsible for the care and management of the collection and for making it available to the public.
The PMG Collection includes fascinating examples of the graphic design process: original art created by leading American artists of the 20th century often overlaid with multiple players of printed plastic featuring supplemental graphics and text – all held together by a range of pressure sensitive tapes and adhesives! The variety of materials and the chemically unstable nature of the plastics and adhesives used in the design process pose significant conservation challenges. Following a comprehensive preservation survey of the collection, the National Postal Museum hired two paper conservators to assist with a project to repair items from the PMG Collection with an emphasis on baseball-related material in preparation for Baseball: America’s Home Run, opening at the National Postal Museum in April 2020. The project, which ran from October 2018 through February 2019, was funded by the USPS and managed by NPM staff.
The project provided the opportunity to perform conservation treatments on some of the most valuable and most fragile items in the collection. During the course of the project, conservators:
completed condition surveys for 798 objects, 260 of which were baseball-related;
repaired 209 objects, 56 of which were baseball-related;
photographed and created cataloging database images for 343 objects; and
completed treatment surveys for 184 objects that will be treated in the future when additional resources are available.
Treatment included surface cleaning, stain reduction, and stabilization of the plastic overlays as well as a range of more complex treatments to fill paper losses and reduce adhesive stains. The following examples illustrate some of the most common treatments performed during the project.
Paper repair is one of the most common conservation treatments performed on the PMG collection. Handling during the production process often results in worn edges that can tear or lead to further loss if not repaired. Torn corners are stabilized with wheat starch paste and long-fibered Japanese paper prior to matting and framing. Acidic supports and backing boards, as evidenced by brown edges, often require further stabilization prior to exhibition.
Plastic overlays are applied to the original artwork as a part of the production process. Throughout the twentieth century, a range of commercially available pressure sensitive tapes were used for this purpose. Many of these tapes contain acidic components that stain and discolor the artwork or damage the plastic. Adhesive residue can be removed from both paper and plastic stamp art overlays with a crepe eraser as seen below; solvents such as ethanol or acetone are used when the adhesive cannot be removed mechanically. Removal of adhesive limits the possibility of future damage to the original object and the risk that the adhesive will adhere to another object.
Plastic overlays can stick to acrylic media, requiring careful removal of the overlay and repair of the paint layer using a range of acrylic-based consolidants in order to prevent further flaking or loss of original media. This acrylic-based stamp art featuring Babe Ruth proved to be in stable condition, requiring only minimal consolidation.
In some cases, loss of support material or media requires more complex treatment. For the pencil study of a Pony Express rider featured below, the severely cockled and creased semi-transparent paper support was repaired with pre-coated Japanese tissue using 6% isinglass in water. Isinglass is a pure form of gelatin adhesive prepared from the air bladders of certain fishes, most commonly sturgeon. Losses were filled with acrylic-toned Japanese paper and isinglass. Multiple humidification and flattening procedures were performed in order to restore planarity.
Throughout the 20th century, art on paper was often mounted onto acidic backing boards that become brittle over time. Storage in the National Postal Museum’s climate controlled vault represents one of the best ways to slow down the rate of embrittlement and minimize the possibility of further damage. In the case of this stamp art featuring John Wesley Powell, the brittle backing board had cracked, tearing the paper support and requiring that the drawing be removed from the damaged board. The backing board was removed mechanically by scraping away layers of board and by using controlled moisture to remove the final layer. The central tear on the paper support was repaired with Japanese paper and wheat starch paste. Minor paint losses along the tear were inpainted with watercolor.
When tape is left in place for extended periods of time, stains on the paper surface can result. In order to stabilize this drawing of Jack London, numerous pressure-sensitive tapes on the cover mat, the backing board, and the clear polyester overlay were removed with a microspatula and a hot air tool. The adhesive residues were reduced with a crepe eraser and with acetone and cotton swabs. The plastic overlay was retained.
These recent advances in caring for the Postmaster General Collection represent an ongoing commitment to the preservation of this important collection of philatelic history. In addition to preserving twentieth century material like the items featured in this post, the National Postal Museum is actively engaged in caring for newly created stamp art: an annual transfer schedule of PMG art from USPS to the National Postal Museum guarantees that newer material is assessed and stabilized in a timely manner.
Many of the 56 items repaired as a part of the project described here will be on view for the upcoming exhibition, Baseball: America’s Home Run, which opens at the National Postal Museum in April 2020.