Glazing process

Fish which is frozen in air blast will often be dipped into clean water afterwards, resulting in a layer of ice on the surface. This glazing process protects the fish from the effects of dehydration in subsequent storage. 

The surface of fired pottery is generally porous and readily absorbs moisture. To conceal outside imperfections, decorate the surface, and make the pottery more or less impervious to water and other liquids, many ceramic objects are glazed, that is, coated with a thin layer of glaze (Tite 2004). The nature of glaze and the glazing process are discussed in Chapter 3. 

Use Manufacture of kraft paper, paperboard, and glass filler in synthetic detergents sodium salts ceramic glazes processing textile fibers dyes tanning pharmaceuticals freezing mix laboratory reagent. food additive. 

Uses Solvent for candy glazes process solvent for pectin, food prods., vitamins, hormones, yeasts, antibiotics, vaccines, medicinal chems. incl. alkaloids, pharmaceuticals, pill mfg., other chems. and prods. raw material for vinegar, acetic acid, ethyl acetate, other ethyl esters, syn. resins, animal feed supplements Regulatory FDA 27CFR 21.62 Trade Name Synonyms SDA-35A [Eastman http //WWW. eastman. com]... 

Up to 100°C, the elimination of hygroscopic water takes place. This moisture may be present due to incomplete drying prior to glazing, or as a result of moisture reabsorbed dming the glazing process. 

Color Matching. Color matching is a process in which a technician prepares a formulation, ie, a mixture of pigments in a desired medium, that has the color effects desired by the customer. A good color match in one medium, eg, plastic, is not always a good match in another medium, eg, ceramic glaze. Thus the medium as well as the processing conditions have to be identical to those used by the customer. 

Polymethacrylates. Poly(methyl methacrylate) [9011-14-7] is a thermoplastic. Itis the acryUc resin most used in building products, frequendy as a blend or copolymer with other materials to improve its properties. The monomer is polymerized either by bulk or suspension processes. Eor glazing material, its greatest use, only the bulk process is used. Sheets are prepared either by casting between glass plates or by extmsion of pellets through a sHt die. This second method is less expensive and more commonly used. Peroxide or azo initiators are used for the polymerization (see Methacrylic polymers). 

Polycarbonates. Polycarbonates (qv) are pardy crystalline thermoplastics with some disorder in the crystalline part and considerable order in the amorphous part. This disorder conveys high impact strength which, combined with its good transparency and outdoor exposure resistance, makes polycarbonates usefiil for vandal-resistant glazing and outdoor lighting. It is easily processed by extmsion and injection mol ding. Various uv and dame-retardant agents are often added. 

The first methacrylic esters were prepared by dehydration of hydroxyisobutyric esters, prohibitively expensive starting points for commercial synthesis. In 1932 J. W. C. Crawford discovered a new route to the monomer using cheap and readily available chemicals—acetone, hydrocyanic acid, methanol and sulphuric acid— and it is his process which has been used, with minor modifications, throughout the world. Sheet poly(methyl methacrylate) became prominent during World War II for aircraft glazing, a use predicted by Hill in his early patents, and since then has found other applications in many fields. 

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