Removing varnishes

Uses Manufacture of viscose rayon, cellophane, flotation agents, ammonium salts, carbon tetrachloride, carbanilide, paints, enamels, paint removers, varnishes, tallow, textiles, rocket fuel, soil disinfectants, electronic vacuum tubes, herbicides grain fumigants solvent for fats, resins, phosphorus, sulfur, bromine, iodine, and rubber petroleum and coal tar refining solvent and eluant for organics adsorbed on charcoal for air analysis. 

Some people find the effects of solvents on the nervous system desirable and purposely inhale (sniff) solvents to induce a form of intoxication. In the United States approximately 15% of high school students have tried solvent inhalation at least once. Solvents suitable for inhalation and abuse are common in the home. Home products that may contain solvents include paints, paint remover, varnishes, adhesives, glues, degreasing and cleaning agents, dyes, printing ink, floor and shoe polishes, waxes, pesticides, drugs, cosmetics, and fuels, just to name a few (Table 11.1). 

Tetrachloroethane is used as a solvent, for cleansing and degreasing metals, in paint removers, varnishes, lacquers, photographic film, resins and waxes, extraction of oils and fats, as an alcohol denaturant, in organic synthesis, in insecticides, as a weedkiller and fumigant and as an intennediate in the manufacture of other chlorinated hydrocarbons (Lewis, 1993). 

When a painting is finished, the artist often applies varnish or lacquer to the painting surface. Varnishes, and often paints, are thinned with turpentine. Turpentine can be used to remove surface varnish. Turpentine is moderately toxic if inhaled or ingested. Carbon tetrachloride, toluene, and methyl alcohol are also used to remove varnish (see Figure 10.2). Carbon tetrachloride and toluene are highly toxic if routinely inhaled. 

The conservators have to choose the right solvents, which usually take off the varnishes easily. The cleaning has to be done very carefully, and it may take a very long time. Often there is overpaint that has to be removed. Today we realize that all restoration should be reversible, but it wasn t so 200 years ago. Today competent inpainting is done over an easily removed varnish. Years ago, restorers often painted oil on oil. Almost all paints were based on linseed oil, which takes 300 or 400 years to polymerize completely by oxidation. If a painting from the 16th century was overpainted in the 17th century, that overpaint has also polymerized and is very difficult to remove. 

Ethyleneglycol Ethylether Acetate, Glycol Monoethylether Acetate or "Ceilosoive" Acetate, CH COO.CHg.CHa.OC Hjj mw 132,16 colorless liq with mild ether-like odor sp gr 0.9748 at 20/20°, njj 1,4030 at 25 fr p -61.7° bp 156.3 , H P 135°F sol in w (20%) and miscible with ale, eth, acet and aromatic hydrocarbons can be prepd by treating ethyleneglycol monoethylether with acetyl chloride. Its toxicity is discussed in Ref 3, p 313. It is used as solvent for NC, oils resins removes varnish and retards blushing in lacquers... 

Oxalic acid is used in the manufacture of dyes, inks, bleaches, paint removers, varnishes, wood and metal cleaners, dextrin, cream of tartar, celluloid, tartaric acid, purified methyl alcohol, glycerol, and stable hydrogen cyanide. It is used in the following industries photographic, ceramic, metallurgic, rubber, leather, engraving, pharmaceutical, paper, and lithographic. 

Stains varnish, oil, and wax Tallate driers Thinners, paint prepared Undercoatings, paint Varnish removers Varnishes... 

MAJOR USES Used in the manufacture of rayon, carbon tetrachloride, floating agents, soil disinfectants, electronic vacuum tubes, optical glass, paint removers, varnishes, rubber cement used as a solvent in phosphorous, sulfur, selenium, bromine, iodine, fats, resins, rubbers, waxes, lacquers used as a chemical intermediate in cellophane, rubber compounds, fumigants, rare earth sulfides, xanthates. 

Products and Uses An aromatic compound that is not in current use in consumer products. It occurs naturally in crude oil also found in gasoline and petroleum mixes. Still found in old cosmetics, perfumes, nail polish remover, airplane glues, lacquers, dry-cleaning products, paint, spot remover, varnish, stain, and sealant. Was used for solvents, coatings, and various other uses. 

Products and Uses Used in paint remover, varnish remover, spot remover, and rubber cements. Precautions Mildly toxic by swallowing, breathing, and skin contact. A skin irritant. 

Products and Uses A chemical added in soap, bleach, drain cleaners, liquid fertilizers, oven cleaners, paint remover, varnish removers, cosmetic cuticle remover, shaving lotions, hand creams, and facial blushes. 

Storage Store in cool, dry, well-ventilated area out of direct sunlight limit quantity stored Uses Intermediate in prod, of trichloroethylene solvent insecticide cleansing and degreasing metals paint removers varnishes lacquers photographic film resins waxes extraction of... 

Lackierung Lackschicht, Lackttbeizug lacquer remover/ paint remover/ varnish remover/ paint stripper Lackentfemer... 

HOCH2C = CCH2OH. White solid, m.p. 58 C, b.p. 238- C prepared by the high pressure reaction between ethyne and methanol and also from BrMgCCMgBr and methanal. Used in electroplating (Ni), as a corrosion inhibitor, and in paint and varnish removal. 

A varnish is often appHed on top of the paint layers. A varnish serves two purposes as a protective coating and also for an optical effect that enriches the colors of the painting. A traditional varnish consists of a natural plant resin dissolved or fused in a Hquid for appHcation to the surface (see Resins, natural). There are two types of varnish resins hard ones, the most important of which is copal, and soft ones, notably dammar and mastic. The hard resins are fossil, and to convert these to a fluid state, they are fused in oil at high temperature. The soft resins dissolve in organic solvents, eg, turpentine. The natural resin varnishes discolor over time and also become less soluble, making removal in case of failure more difficult (see Paint and FINNISH removers). Thus the use of more stable synthetic resins, such as certain methacrylates and cycHc ketone resins, has become quite common, especially in conservation practice. 

Tetrahydronaphthalene [119-64-2] (Tetralin) is a water-white Hquid that is insoluble in water, slightly soluble in methyl alcohol, and completely soluble in other monohydric alcohols, ethyl ether, and most other organic solvents. It is a powerhil solvent for oils, resins, waxes, mbber, asphalt, and aromatic hydrocarbons, eg, naphthalene and anthracene. Its high flash point and low vapor pressure make it usehil in the manufacture of paints, lacquers, and varnishes for cleaning printing ink from rollers and type in the manufacture of shoe creams and floor waxes as a solvent in the textile industry and for the removal of naphthalene deposits in gas-distribution systems (25). The commercial product typically has a tetrahydronaphthalene content of >97 wt%, with some decahydronaphthalene and naphthalene as the principal impurities. 

Many older finishes can be removed with single solvents or blends of petroleum solvents and oxygenates. Varnish can be removed with mineral spirits, shellac can be stripped with alcohols, and lacquers can be removed with blends of acetates and alcohols (lacquer thinners). The removal mechanism is one of dissolving the coating, then washing the surface or wiping away the finish. This method is often used to reamalgamate or liquefy old finishes on antique items of furniture. 

Laminates. Laminate manufacture involves the impregnation of a web with a Hquid phenoHc resin in a dip-coating operation. Solvent type, resin concentration, and viscosity determine the degree of fiber penetration. The treated web is dried in an oven and the resin cures, sometimes to the B-stage (semicured). Final resin content is between 30 and 70%. The dry sheet is cut and stacked, ready for lamination. In the curing step, multilayers of laminate are stacked or laid up in a press and cured at 150—175°C for several hours. The resins are generally low molecular weight resoles, which have been neutralized with the salt removed. Common carrier solvents for the varnish include acetone, alcohol, and toluene. Alkylated phenols such as cresols improve flexibiUty and moisture resistance in the fused products. 

For large motors, the practice is to wind the stator with formed coils (Figure 9.2). The coils are pre-formed and cured before insertion into the stator slots. They are insulated with resin-rich glass and mica paper tapes. The process of impregnation is therefore termed resin-rich insulation. The completed formed wound stator is then heated to remove trapped moisture and finally impregnated in varnish class F or H as required, under vacuum and pressure. The stator is then cured in an oven as described above. The process of insulation and curing conforms to powerhouse insulation requirements. This practice facili-... 

Lack, m. lacquer, japan varnish lake (the pigment) lac. -abbeizmittel, n. varnish remover. -anstrich, m. coat of lacquer or varnish. 

Lack-auflosungsmittel, n. varnish remover, -aufstrich, m. = Lackanstrich. -beize, /. varnish remover, -benzin, rt (Painta) min-... 

Prior to running the casing string into the well the mill varnish should be removed from the outer surface of the casing. The removal of the mill varnish is necessary to ensure that the cement will bond to the steel surface. 

---