SEE A TEAR on a piece of paper? Stick some tape on it. It's a common sense quick fix to keep important paper in one piece. But for people in charge of priceless works of art, tape is a nightmare.
Unwitting conservators of the past used standard sticky tape to try and hold together famous but fragile treasures, such as the Dead Sea scrolls and drawings by filmmaker Federico Fellini. The trouble is that, in addition to ruining the aesthetic integrity of a piece of art, the adhesive on tape can cause discoloration over time. Certain types of tape can even bleed past where they were placed and alter the visual appearance of the work.
Modern art restorers have traditionally used solvents and intense humidity to loosen tape, methods that can damage the piece or present a toxic hazard for restorers. Now, a team of chemists from the University of Florence has developed a new treatment for the sticky affliction that's safe for humans and doesn't damage the art.
The method starts with hydrogel, a type of gel with high water content used in a variety of common objects, from plastics to pills. The hydrogel used by the Italian researchers was between 95 and 98 percent water. The other five to two percent is made of intersperced nano-sized droplets of organic solvents.
(Left) Detail from Michelangelo's Sistine Chapel; (Right) a 16th-century drawing reproducing the same detail. An inscription "di mano di Michelangelo" (from Michelangelo's hand), on the bottom-left side of the drawing, was hidden by a tape and revealed after restoration.
“The gel is the same composition as contact lenses” and just a millimeter thick, says Piero Baglioni, one of the chemists involved with developing the hydrogel. Conservators can cut and shape the material to the size of the tape they intend to remove. It's then laid on top of the tape, and after only a few seconds, the particles from the hydrogel transfer to the tape, breaking apart adhesive from the paper's fibers.
Baglioni and the other chemists tested their method on a 16th-century sketch that partially depicted a figure from Michelangelo's Sistine Chapel. When the tape was removed, the inscription “di mano di Michelangelo” (from Michelangelo's hand) was visible underneath written in ink — although art conservators remain skeptical that the drawing actually came from the famed Renaissance artist. The gel was also able to lift adhesive from paper fibers in a painting by artist Lucio Fontana.
The hydrogel offers promise for conservators of historic documents, too, since tape is also their frequent nemesis. In his work as director of paper and photograph conservation at the Northeast Document Conservation Center in Massachusetts, Michael Lee has seen duct tape and Scotch tape adhered to important documents. He estimates that as many as 30 percent of the restoration projects they conduct deal with removing tape.
“We've had documents dating to the 1700s that someone in the 20th century applied tape to,” he notes.
For hardier documents, his team has used solvent baths, in which they immerse a document in a solution that dissolves adhesive. When that option is not available, they've also used agarose blocks. Similar to the method recently used in Italy, agarose blocks are gelatinous solvent blocks that release localized moisture to dissolve adhesive.
While better methods to remove adhesive damage are welcome, Lee notes that once tape has been applied, an object's full value can never really be restored.
“Tell your audience to stay away from tape” he says. “An object that has a tear will have one value, and if you apply tape, it will drop.”
Lead Image: A conservator removes tape after hydrogel unsticks its adhesive.
PHOTOGRAPH COURTESY PIERO BAGLIONI