Topics in Photographic Preservation 1995, Volume 6, Article 8 (pp. 111-111)
Frequently exhibition or curatorial needs call for a work of art to be sealed in its frame to protect it from possible variations in the moisture content of its environment. One option for creating a sealed package for matted works of art consists of the following:
The edges of the glazing must first be softened with a file for acrylic or sharpening stone for glass. A strip of 1/4″-wide 415 adhesive should be applied to the sides of the glazing, and folded around and pressed onto the front edges. A sheet of Marvelseal, larger than the whole package, should then be placed under the package and folded onto the 415 on the sides and front edges of the previously cleaned glazing. A heating iron is then used to bond the polyethylene on the inside of the Marvelseal to the 415. When a bond is achieved, the Marvelseal will turn matte and wrinkled and cease to be shiny. Corners can be trimmed down to a small overlap and tacked down with the iron.
If the edges of the art are not near the edges of the mat, they should not receive much heat. The excess Marvelseal should be trimmed so that the portion on the front of the glazing will hide under the rabbet of the frame to be used. If the sealing is to be kept in place for an extended period, a thin strip of cobalt salt humidity indicator card can be affixes to the edge of the window mat so that it will be under the Marvelseal and hidden by the lip of the frame unless someone who is monitoring the condition of the package looks hard at an oblique angle to observe it.
If no heat can be used, the Marvelseal can be applied with its nylon side out and its polyethylene side cut-the reverse of the normal application. The nylon will stick well to the 415 without any heat, unlike the polyethylene. Here the corners can not be ironed shut as they were in the other package. Leave an excess of Marvelseal on the corners. When the edges are sealed, pull the excess at the corners around to the back of the package and tape it down. This package can not be expected to have as great a sealing capability as the heat-sealed package.
Hugh Phibbs is coordinator of preservation graphic services at the National Gallery of Art in Washington, DC.