Picture varnish coating

In view of the above findings, what may we choose for use as a picture varnish that will have little or no tendency to crosslink Polymers of the perfluoroacrylic esters exhibit no such tendency but require solvents of questionable appropriateness (5). Moreover, if the coatings are used indiscriminately in making re-... 

Properties Yel. brittle amorphous lumps or powd. turpentine-like fresh resinous odor sol. in alcohol, acetone insol. in benzene, aryl and aliphatic hydrocarbons, water sp.gr. 1.05-1.09 m.p. 135-150 C soften, pt. 100-130 C iodine no. 112-141 sapon. no. 145-157 ref. index 1.545 Uses Binder in lacquers and paper/picture varnishes emulsion stabilizer in cosmetics natural flavoring agent in alcoholic beverages in food-pkg. adhesives in food-contact coatings... 

Coatings are applied to and act on surfaces that are visible at the time of application, such as picture varnishes or sealants of porous edges before applying adhesives. 

Role of polymer Adhesive/coating/consoli-dant/moulding material A brief description of the tested conservation application is valuable Cellulose acetate was rejected as a picture varnish... 

Physical properties Tensile strength, hardness, extensibility, glass transition temperature These data (derived from manufacturer s literature or practical experience) indicate the limits of use PVAL coatings form strong films but have little adhesion to picture varnish... 

Cellulose acetate in an acetone-soluble form became widely available during World War 1 as a coating for aircraft fabric, dope . CA displaced cellulose nitrate, which was too inflammable. CA was first used, apparently without a plasticizer, in a solution in acetone for fixing pigments on paper and stone (Scott, 1923) and as a consolidant for cloth and other materials (Plenderleith, 1934). It was rejected in 1937 as a possible picture varnish (Stout and Cross, 1937). CA has been largely replaced for conservation uses by modem materials. 

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