NOTES ON A METHOD FOR CONSOLIDATING LEATHER
Morgan W. Phillips
2 TEST APPLICATIONS
SMALL SAMPLES OF DETERIORATED LEATHER were soaked in the consolidant solution, wrapped in aluminum foil, and embedded in sand that had been preheated to about 45°C–50°C. The sand, with the samples, was placed in an oven and maintained at roughly this temperature for four hours. The purpose of the sand was to buffer the temperature changes of the poorly controlled oven, and to draw off any heat of exothermic reaction from the samples. The samples were then withdrawn, unwrapped, and dried to remove solvent and residual monomer. The samples were dried by overnight warming followed by a week's airing at room temperature. Most of the samples continued to stiffen slightly over the following weeks. The following describes the uneven but encouraging results.
An early-nineteenth-century American calfskin, brittle and rather crumbly, was greatly strengthened, though also darkened. The strength increase was easily sensed by abrading the leather or by breaking narrow strips in tension. The treatment, however, made the leather more subject to cracking on being folded sharply. Another, similar, piece seemed completely unaffected by the treatment—neither strengthened nor darkened.
A red-dyed and gold-striped late-nineteenth-century calfskin, thoroughly red-rotted and intolerant of bending, became remarkably strong in tension, and was darkened only on the reverse side. Though stiffened, the treated leather became tolerant of repeated gentle flexing; it still cracked on being folded sharply. The gilding was unaffected.
A late-nineteenth-century suede, partially rotted, was made much stronger in tension and much more resistant to abrasion. It was darkened more than would be desirable, but mostly on one side.
Two late-nineteenth-century embossed leathers from wall coverings, both completely rotted, were considerably strengthened. The consolidant attacked the leafed-and-painted finishes on one of the leathers, but did not disrupt the metal leaf or paint on the other. Neither example was darkened at all—either on the finished surfaces, on the reverse, or in spots where the finishes had broken away.
The strengthening of these wall covering leathers was somewhat uneven. Pre-treatment of one small sample with a dilute solution of the polymer (polymethyl acrylate in toluene) followed by the precipitation consolidation produced a more uniform, though darkened, product. Perhaps, besides contributing some strength on its own, polymer deposited on the fibers from solution enhanced subsequent deposition of precipitated polymer.