Removability picture varnish

The useful life of a polymer has to be defined for conservation. Feller developed a rule of thumb for classifying materials by their photochemical stability, a useful tool that should inform aU stages in the conservation process, from planning to use (Table 2.4). In most fields, it is expected that a conservation treatment will have to be reversed in the future. For instance, picture varnishes have traditionally been replaced every 80-120 years and stained glass window installations every 2-300 years. It is likely that a material used for temporary fixing may never be entirely removed (Section 1.3). It is therefore necessary that even these have long-term stabihty. 

Smith, G. D., Johnson, R. (2008). Strip Teas - solubility data for the removal (and application) of low molecular weight synthetic resins used as inpainting media and picture varnishes. Western Association for Art Conservation Newsletter, 50(1), 11—19. 

Lomax, S. Q., Fisher, S. L. (1990). An investigation of the removability of namrally aged synthetic picture varnishes. Journal of the American Institute for Conservation, 29, 181-191. 

Use Removal of greases and oils from metal, plastic, elastomer, and paint or varnish surfaces. Used with all cleaning techniques on assembled motors and parts, electronic devices, precision components, motion-picture film, refrigeration systems, etc. Also used for isolation of viruses, for fire extinguishing, and as dielectric coolants. 

Once the pod tree [Caesalpinia spinosa) is harvested, it is washed and dried, and then the seed is removed from the pod. Following the separation, the separately ground pit shell, which is an extraordinary product, is exported as a raw material for the production of tannic acid, which is widely used in the chemical, paint, and high-quality fur industries and pharmaceuticals. The seeds, or the pips, after undergoing a thermal-mechanical process, result in a gum from the endosperm, which is an alternative to the traditional rubber in the global food industry, pharmaceuticals, paints, and varnishes, among others. This gum has been approved by resolution of September 26, 1996 (ECC N° E-417) by the European Community for use as a thickener and stabilizer in food for human consumption. Thus came into picture the global market for food hydrocolloids as an alternative product to the locust bean gum, produced in Spain and the Middle East. 

Epoxy resins have been used in canvas picture conservation. An unfortunate use as a varnish caused problems in identification and removal (Keck and Feller, 1964). Epoxy resin adhesives have been used for sticking threads across tears in canvases and also as a filler (Berger and Russell, 1993). The formulations need to be of sufficiently high viscosity to prevent absorption into the canvas, but must be flexible enough to respond to movement in the fabric. 

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