G. M. Berry, S. P. Hersh, P, A Tucker, and W. K. Walsh (School of Textiles, North Carolina State Univ , Raleigh, NC 27607). Reinforcing Degraded Textiles, Part II: Properties of Resin-treated, Artificially Aged Cotton Textiles." In John C. Williams ed. Preservation of Paper and Textiles of Historic and Artistic Value, Papers of the August 1976 Meeting of the American Chemical Society in San Francisco American Chemical Society, 1977. 403 Pp.
Soluble nylon was not tested, but 23 other resins and monomers were Some usually thought to work didn't, and some not usually used did. A polyvinyl alcohol, Elvanol T-25, not only didn't strengthen the degraded cloth, it made it 24 times LS rigid Two PVA copolymers, a polyvinyl butyral, gum arabic and carboxymethylcellulose all had a similar effect.
The most successful reinforcing formula, K-3 with 1.2% PE, increased tearing strength by 55% without affecting flexural rigidity or tensile strength. This is an acrylic latex (Rhoplex K-3 from Rohm and Haas Co. with a glass transition temperature of -32°C) applied in combination with 1,2% polyethylene (Moropol 700 from Mortex Chemical Products) Glass temperature is the temperature at which the resin changes from a relatively flexible to a relatively stiff material. Neither component of the mixture was effective alone.
The fabrics on which this testing was done were artificially aged by 3 methods (heat, irradiation and acid hydrolysis) and compared on 5 dimensions with 2 samples of naturally degraded pre-Columbian cottons to find the best way of duplicating natural aging They concluded that not all aging mechanisms are alike, since textiles have various components, and a given sample may be affected over the years by any combination of the following factors: oxidation, heat, mechanical stress, radiation, moisture, and microbiological and enzymatic attack. The various natural and artificial samples differed in degree of crystallinity, degree of polymerization (i.e. how intact or broken up the long cellulose molecules were) and extent of oxidation as a function of loss of strength--i.e., none of these was a reliable index of loss of strength, though there was some correlation. However, that didn't stop the investigation, since strength was easy to measure directly.
The study did not intend to test reversibility or safety of the treatments--this work still remains to be done. Some polymers formerly thought to be harmless and reversible (polyvinyl alcohol and cellulose nitrate) have turned out not to be. If consolidation is necessary to the survival of the artifact, but no reversible treatment is known, many conservators use a treatment that at least is effective, permanent and harmless. This study was mainly concerned with effectiveness, which it tested first since there is no point in testing the reversibility of an ineffective method
Timestamp: Sunday, 03-Mar-2013 21:33:19 PST
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