Particularities of Parchment — The Conservation Center

As a conservation laboratory with 40 years of history and ten conservation departments, we see a wide variety of items for treatment. All come with their nuances and peculiarities, and parchment is no exception. Parchment - writing sheets made from prepared animal skins - presents particular challenges for conservators and framers. While everything may seem ordinary, what often happens inside a parchment piece's frame tells another story.

*An Angel from the Baptism of Christ,* before treatment

An Angel from the Baptism of Christ arrived at The Conservation Center framed. The parchment has been mounted with pressure-sensitive hinges, and the hinge at the upper left corner was lifting away from the mount. The artwork exhibited severe distortion and handling dents throughout the piece, as well as abrasions. There is age-related discoloration throughout that would not be addressed during treatment due to the nature of the materials and mixed media; aqueous stain reduction would not be appropriate, and general discoloration is considered inherent.

*An Angel from the Baptism of Christ,* before treatment verso

Katrina Flores, Associate Conservator of Works on Paper, began treatment by carefully freeing the sheet from the mat, and lifting away the paper hinges with the appropriate mechanical and poultice techniques. The sheet was then selectively surface cleaned with a soft brush and soot sponge to reduce surface grime with consideration of the mixed media. Then, the sheet was humidified in a Gore-Tex package and flattened between blotters to reduce surface deformations as best as possible.

One of the particular challenges with framing parchment is hinging. Hinge mounting uses a secondary material, like archival pressure-sensitive tapes or Japanese tissue with methylcellulose adhesive, to attach the artwork to the mount board. Parchment and pulp are made of different organic materials and respond to humidity at different rates. When a parchment sheet is restrained too tightly during framing, it is susceptible to breakage when it naturally moves and distorts due to humidity changes. Standard hinging methods may not be appropriate, and techniques that allow for expansion are therefore considered.

For An Angel from the Baptism of Christ, Senior Conservation Framer Scott Dietrich's research led him to a creative solution - expandable polyester pass-through hinges. A pattern of slits is cut into the polyester hinges, allowing them to expand and shrink as the parchment requires. The plastic of the polyester hinges will not respond to humidity itself but provides the flexibility the parchment needs.

The expandable polyester pass-through hinges are secured to the parchment with small tabs of Japanese tissue adhered with wheat starch paste. The hinges are then passed through slots cut into the archival 4-ply mat and secured to the back of the board using acid-free double-sided tape. This hides the hinge from view and gives the illusion that the work is floating on the mount. A 4ply mat board spacer between and mount and the 12ply top mat allows the hinges and artwork the space to move. Finally, the work is topped off with Optium Museum Acrylic, a conservation grade, anti-reflective, anti-static acrylic glazing that protects against UV light rays, and tape sealed to prevent moisture and dust from entering the package.

*An Angel from the Baptism of Christ,* during reframing

*An Angel from the Baptism of Christ,* after treatment

Now reinstalled into the existing frame, An Angel from the Baptism of Christ can be safely displayed for years to come.

Carissa Tonner