41st Annual Meeting – Book and Paper Session, May 30, "A Technical Study and Conservation Project of Roy Lichtenstein's Screenprint on Plastic 'Sandwich and Soda', 1964," by Marion Verborg

The fourth presentation of the Book and Paper Group session examined neither a book nor an object on paper, but instead a print on plastic: Roy Lichtenstein’s 1964 Sandwich and Soda, a screenprint in red and blue ink on plastic. The object occupies a sort of conservation no-man’s-land: it’s a print, so it’s not something an objects conservator would normally deal with, but it’s on plastic, which is not a paper conservator’s area of expertise. Marion Verborg, Craigen W. Bowen Paper Conservation Fellow at the Straus Center for Conservation and Technical Studies at Harvard Art Museum, jumped into the void with this print on plastic, part of the portfolio X + X (Ten Works by Ten Painters), published as an edition of 500 by the Wadsworth Athenaeum in Hartford, Connecticut, in 1964.
Verborg’s problem was typical for a paper conservator—removing degrading pressure-sensitive tape that someone had once used to hinge the object. The Harvard Art Museum has more than one copy of the work. One print had an office-type pressure-sensitive tape, and the other had a Filmoplast-like tape. Both supports showed a small amount of planar distortion. There were already dark stains around the pressure-sensitive tape areas, causing concern that the adhesive would continue to sink into the media. The problem was complicated by the adhesive’s being directly adhered to the ink of the object, and by the plastic support, which would probably react poorly to heat application.
Verborg viewed other copies of the print in other institutions, and had access to the records of the print shop where they were made, as well as to recorded interviews with the artist and the opportunity to get information from Lichtenstein’s wife and a printer’s assistant from the print shop.
One interesting question arising from Lichtenstein’s use of a transparent support is which side is the recto? Lichtenstein, when asked many years later, said that the print should be ink-side up, which is reasonable for a print. However, both the printer’s assistant and Mrs. Lichtenstein remember that the ink should be on the verso, so that you have the glossy effect as well as the extra depth from looking through the support to the image. This is further supported by having the drinking glass in the composition on the right, where a right-handed person would normally place it.
Verborg had the materials tested with GCMS, FTIR, Raman Spectrometry, and LDI-MS (Laser Desorption Ionization Mass Spectrometry).  The original printer’s invoice called the plastic “acetate,” but this seems to be a generic term for any clear sheet plastic.  Analysis revealed it to be polystyrene, which is no longer available in clear sheets like this, and today we are more familiar with it in products like Styrofoam. The inks used a polystyrene binder as well, with PB 15 (phthalocyanine blue) as the colorant in the blue ink, and chrome red and some barium sulfate in the red ink. The paper-type tape was made of cellulosic material and the clear tape used PVA for both carrier and adhesive.
No one seems to sell clear polystyrene sheets anymore, so Verborg had to make do with other plastics for her mock-ups.  As expected, heat caused the sheets to warp, making a heat treatment unwise. After removing the carrier, Verborg was left with sticky adhesive. Finding the right solvent for aged PVA adhesive that wouldn’t affect polystyrene would be difficult, as demonstrated by evidence of previous solvent tests on the ink layer, so she had to get creative, especially without the ability to make exact mock-ups. She finally tried sprinkling cellulose powder on the adhesive and then using a silicon color shaper to move the cellulose powder around, allowing her to remove the adhesive in small cellulose-powder/adhesive balls, leaving a clean surface.
This research has not only provided better insight into the working process of Roy Lichtenstein and his transition into experimenting with unusual print supports (one of the great advantages of screen printing) but also addresses other more universal problems such as the artist’s memory versus the artist’s probable intention, the unreliability of the labels people give to the materials they use, and how to remove sticky adhesive residue from a delicate surface.