Varnish picture

R. L. EeUer, E. H. Jones, and N. Stolow, On Picture Varnishes andTheir Solvents, Intermuseum Conservation Association, OberUn, Ohio, 1959 repubhshed The National GaUery of Art, Washington, D.C., 1985. 

Methyl and ethyl methacrylate polymers, although extensively used in Industry, do not possess the solubility characteristics (low polarity) that would make them appropriate for use over traditional oil paintings and other organic-based museum objects that might be sensitive to polar solvents such as alcohols, ketones and esters. Poly(n-butyl methacrylate), offered as an artists varnish in the late 1930 s, did not become widely accepted in the war-disrupted decade that followed. Accordingly, early in 1951, our laboratory began a detailed study of the higher alkyl methacrylate polymers for potential use as picture varnishes (1). 

To be suitable for use in museum preservation and restoration practice, picture varnishes must have a number of defined characteristics (a) they must not interact with the object in a detri-... 

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-... 

Feller, R. L., Stolow, N. and Jones, E. B., "On Picture Varnishes and Their Solvents", Press of the Times, Oberlin, Ohio, 1959 revised edition of Press of Case-Western Reserve, Cleveland, 1971 both currently out of print. 

Table 5.3 Prominent peaks in the mass spectrum of rosin (see Figure 5.10). Compounds marked with an asterisk are mentioned as constituents of diterpenoid varnishes from old pictures in the literature...

Low molecular weight cyclohexanone resins have been used as picture varnishes since the 1950s. Their synthesis from cyclohexanone and methyl cyclohexanone in the presence of... 

The varnish on a modern painting ( Mont Saleve by Alexandre Perrier, 1916, private collection) showed a mass spectrum (Figure 5.19b) almost identical to that of Ketone Resin N. The use of a cyclohexanone resin as a picture varnish seems uncommon because copolymers such as AW2 were preferred by conservators [62]. An investigation into cyclohexanone resins by direct temperature-resolved MS (DTMS) is reported in the literature [22, 64]. Similar mass spectrometric patterns were achieved with masses accurately reflecting the values expected for the oligomers. 

C. Theodorakopoulos, The Eximer Laser Ablation of Picture Varnishes, PhD thesis, Royal College of Art, London, 2005. 

The first synthetic polymers to be used as paint varnishes were acrylic and vinylic resins. Poly(vinyl acetate) (PVAc), commercialized under the name Mowilith by Hoechst and Vinylite by Union Carbide, has been used in conservation as an adhesive since 1932 and in 1937 it was proposed as a picture varnish by Stout and Cross [63]. PVAc was soon rejected as a varnish because, despite its light stability and good solubility in organic solvents, it demonstrated poor optical properties in terms of colour saturation and the tendency to pick up dirt due to its low glass transition temperature. 

Poly(butyl methacrylate) (PBMA) began to be used as a picture varnish in the early 1930s. It encountered a considerable success because of its resistance to yellowing, adequate flexibility, no dirt pick-up and good solubility in nonpolar hydrocarbon solvents. Products based on PBMA, such as Elvacite 2044 and Elvacite 2045 by Du Pont, were abandoned when it was discovered that under light exposure they cross-link to an unexpected extent becoming insoluble [64]. From this point of view acrylic copolymers based on methyl and ethyl acrylates/methacrylates show a much better long-term stability. 

R.S. Bems and E.R. de la Rie, Exploring the optical properties of picture varnishes using imaging techniques, Stud Conserv. 48, 73 82 (2003). 

To Fix and Finish tie Picture.—When the plate has been well washed after the development, by pouring water over it from a jug, the yellow iodide of silver should ho dissolved out by means of either a saturated solution of hyposulphite of soda, or a solution of cyanide of potassium—strength about five grains to the ounce of water. This should be poured over the plate, and should be allowed to run backwards and forwards over it until the whole of the yellow iodide of silver in the plato has disappeared aftor which it should bo thoroughly well washed, by pouring water over it from a jug, and sot up to drain and dry or it may be dried before a fire. It is then ready to bo varnished,... 

The best Mud of varnish to apply to a cold plate Is made by dissolving powdered dammara resin in benzol. This is potued over the picture in the Bame way as the collodion on the plate. It dries in a few minutes. Cut a better varnish, used with a heated plate, is made by dissolving shell-lac in alcohol. This is called spirit varnish. Before applying it, the plate should be heated before a fire to about 100°, aud after applying it, to about 160°. When dry, this varnish is extremely hard and diUioult to scratch, and it protects the picture effectually from injury in printing. 

Paintings begin to change from the day they are completed and while this may not be noticeable during the lifetime of the painter and the patron, they would certainly be shocked if they could see the ultimate ravages of time. Colours fade or darken under the influence of heat, light, dirt, and atmospheric gases, varnishes turn dark brown, and cracks may cover the picture from end to end. These cracks are... 

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. 

Most soluble resins that are being used as consolidants in conservation today are also used in picture varnish. Thus these resins have a history of satisfactory use that, in the case of poly(vinyl acetate), extends over almost 60 years (6). Consolidants can cause some darkening of wood surfaces much in the way wetting them with water deepens their color, but with proper technique they will not leave a shiny surface film (7). Because excessive... 

Xylene is the most important aromatic solvent used in the paint, varnish and adhesives industries, and is also a starting material in the production of plastics. It enters the human organism by the same routes as benzene and toluene, and the clinical picture is similar to that for toluene. 

Chlorinated organic compounds are used in large quantities in the paint, varnish and chemical industries because of their remarkable properties as fat solvents and their nonflammability. Entry into the human organism is via the lungs, the skin, and the gastrointestinal tract. The clinical picture includes irritation of the mucous membranes, narcotic effects, liver damage (fatty infiltration), and damage to the heart muscle and kidneys. Also, chlorinated hydrocarbons can cause the CHC syndrome. 

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. 

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... 

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