2 TREATMENT PROPOSAL

BECAUSE IT WAS NECESSARY to consolidate the embrittled tracing paper and to preserve what remained of the fragile pen and ink lines, it was decided to line the tracings. The use of aqueous adhesives had to be rejected. Not only is tracing paper usually reactive and expansive when wetted, but in this case any attempt to moisten the sheets would cause the delicate lines to fall away completely. Therefore, a solution to the problem, previously described for mounting deteriorated textiles, was adapted and a heat-seal adhesive, poly (vinyl acetate) PVA, was chosen.6 This material is well documented and has an excellent aging record.7 Its use as an adhesive is straightforward and efficient. It is also reversible since bonding takes place as the result of the PVA adhering to not impregnating, the paper fibers.8 Because the resin is available in several viscosity grades, one with a relatively low softening point in relation to the other heat-seal adhesives was considered the best in this case. Excessive heat would cause further deterioration of the fragile tracings.

The lining material chosen, Cerex Spunbonded Nylon Gossamer Web, was both lightweight and transparent enough to preserve the thinness and translucency typical of tracing paper.9 Flexibility of the lining would be provided by spraying the adhesive, thereby preventing the stiffening that would result if the web were filled with resin as by brushing.10 In this way, it was hoped to retain the stylus indentations and the wrinkled, undulating surface topography which give these sheets their particular character.