MCI Project Summaries 2008 - Smithsonian Institution

MCI 6208 Marble Columns
MCI Staff: Claire Gervais, Carol A. Grissom, Marion F. Mecklenburg
During renovation of the Patent Office Building prior to the reopening of the Smithsonian
American Art Museum in 2006, temporary walls were erected by a contractor between stone
columns in the Lincoln Gallery to provide additional wall space for display of artwork. Fullheight
walls were adhered to original marble columns or pilasters and new marble floor tiles with
silicone adhesive. Over “entryways” in temporary walls, by contrast, metal plates were attached
to the upper portions of stone columns or pilasters with epoxy resin, and acrylic headers were
mechanically attached to the metal plates. When one of these walls in the southern area of the
gallery was removed in late 2007, disfiguring white silicone was left on one column and the
adjacent floor where the wall had been attached with that adhesive. Detachment of the epoxyattached
metal plate on the other column resulted in removal of a layer of stone crystals
embedded in the epoxy, while residues of epoxy were also left on the stone.
After testing, white silicone adhesive residues were removed from the column and floor
with poultices containing a proprietary chemical mixture, Amtex-CCR Silicone Dissolver.
Residual silicone oils remained on the stone column, however, leaving a dark snake-like pattern
where adhesive had been applied. Following test application with dilute resins, including methyl
cellulose, Acryloid B-72, Butvar B-98, and Aquazol 50 and 200, a dilute coating of methyl
cellulose was applied around the stains to reduce contrast with the stone. Epoxy residues were
partially removed from the column with commercial methylene-chloride-based paint stripper.
Pencil lines were removed with an eraser from where edges of walls had been, and paint lines
were removed with isopropyl alcohol. Experiments were made in the laboratory on the detached
metal plate using heat, liquid nitrogen, solvents, and a strong base in order to simulate alternative
methods for future removal of metal plates adhered with epoxy.
In future, residues of the white silicone adhesive could be removed with the Amtex-CCR
Silicone Dissolver when walls are taken down, although the process is somewhat tedious and
odiferous. Remaining stains could be disguised with a dilute coating of methyl cellulose, but
advances in silicone stain removal should be investigated at that time. The most promising
solution for future removal of epoxy-attached plates is application of heat by induction to allow
the epoxy/stone or metal/paint bond to be broken without damaging the stone.
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