Modern Finishing

The various leather articles with their specific requirements each require a specific optimized process in the tannery. Classifying leather finishes according to, say, the binders used or the method of application, the appearance or the ready-produced leather article is thus possible only to a limited extent. Frequently there are many different ways of producing the desired article. Leather finishing is therefore regarded as being more an art than a science. 

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In Chapter 12, we mentioned that the departure from the 100 per cent solids of the old oil paints, to the lower solids of modern finishes, was a consequence of the demand for paints with better performance. The paint industry s determination to provide the improved properties at higher solids was also mentioned. We have already seen in Chapter 14 how the epoxy/polyamine system meets these requirements. The finishes under discussion in this chapter are another approach to the problem. 

Lewis, J. Mildew proofing of wool in relation to modern finishing techniques. Wool Sci. Rev., 1(46) 17-29(1973). 

McMordie, B.G., Impact of Smooth Coatings on the Efficiency of Modern Turbomachinery, 2000 Aerospace/Airline Plating Metal Finishing Forum Cincinnati, Ohio, March 2000. 

The main difference between the two types are that the reaction products of the silico fluoride types are less soluble in water and are also harder, which may give better in-service performance but at a slightly higher material cost. However, with recent developments in floor-laying techniques, the concrete substrates for industrial floors are laid with much more dense low-porosity surfaces, so that neither silicate nor silico fluoride treatments are as effective as they used to be, when the concrete used had a slightly more open finish and hence was more receptive to these treatments. With modern concrete floors, it is imperative to wash any material not absorbed into the surface within a short period. Otherwise, unpleasant white alkaline deposits, which are difficult to remove, may occur. 

The modern motor car is made from steel, zinc or zinc alloy-coated steel and some plastic parts, all of which require painting. The main component is the body shell, made from the above metals, and this is coated in a continuous production process. A full finishing system with all four coatings is usually applied for maximum protection and a high quality appearance. 

A vitreous enamel coating is, as the name implies, a coating of a glassy substance which has been fused onto the basis metal to give a tightly adherent hard finish resistant to many abrasive and corrosive materials. The purpose of modern vitreous enamels is twofold, i.e. to confer corrosion protection to the metal substrate and at the same time to provide permanent colour, gloss and other aesthetic values. 

Commercially produced amines contain Impurities from synthesis, thus rigid specifications are necessary to avoid unwanted Impurities In final products. Modern-day analytical capability permits detection of minute quantities of Impurities In almost any compound. Detection In parts per million Is routine, parts per billion Is commonplace, and parts per trillion Is attainable. The significance of Impurities In products demands careful and realistic Interpretation. Nltrosatlng species, as well as natural amines, are ubiquitous In the environment. For example, Bassow (1976) cites that about 50 ppb of nitrous oxide and nitrogen dioxide are present In the atmosphere of the cities. Microorganisms In soil and natural water convert ammonia to nitrite. With the potential for nitrosamine formation almost ever-present In the envlronmeit, other approaches to prevention should Include the use of appropriate scavengers as additives In raw materials and finished products. 

Washing machines currently on the market are constructed almost exclusively with drums and laundry tubs of corrosion-resistant stainless steel or with an enameled finish that is inert to alkaline wash liquors. Nevertheless, various machine components are made of less detergent resistant metals or alloys. To prevent corrosion of these parts, modern detergents contain corrosion inhibitors in the form of sodium silicate. The colloidal silicate that is present, deposits as a thin, inert layer on metallic surfaces, thereby protecting them from attack by alkali. 

Pharmaceutical substances form the backbone of modern medicinal therapy. Most traditional pharmaceuticals are low molecular mass organic chemicals (Table 1.1). Although some (e.g. aspirin) were originally isolated from biological sources, most are now manufactured by direct chemical synthesis. Two types of manufacturing companies thus comprise the traditional pharmaceutical sector the chemical synthesis plants, which manufacture the raw chemical ingredients in bulk quantities, and the finished product pharmaceutical facilities, which purchase these raw bulk ingredients, formulate them into final pharmaceutical products, and supply these products to the end-user. 

The modern automated sorters (Fig. 8.1) are machines which examine feed lumps on an individual basis, compare the measured properties of each lump with predetermined criteria, and then separate the lumps, using an applied force, into different products according to the measured properties. A sorter treating -120 + 60 mm material typically treats 85-100 t/h and a imit treating -60 + 30 mm material - 30-40 t/h. Ore types treated by sorters aroimd the world include different types of rocks (Mokrousov and Lileev 1979 Salter and Wyatt 1991 Cutmore and Eberhard 2001). These sorters were installed for one of the following duties pre-concentration of plant feed, intermediate product production, finished product production. The main benefits are as follows ... 

Berridge, S. A. 1992. Finishing processes. In Modern Petroleum Technology, ed. G. D. Hobson, pp. 517-575, London Institute of Petroleum. 

The construction of relativistic and nonrelativistic E-coefficients is therefore at the centre of an efficient electronic structure program a paper describing how to organize this on modern multi-node computers is nearly finished [15]. Relativistic symmetry relations can be exploited to reduce the number of independent coefficients which need to be calculated. 

The key to the successful application of high performance, pourable nitrocellulose plastisols lies in a reasonably priced, high quality source of fine-particle, at least partially colloided, spheroidal nitrocellulose. Here we are speaking of particles much finer than the well-known ball powder, produced by the Olin Mathieson Chemical Co. for small arms for over 30 years (7). Actually, particles on the order of 5-50/x diameter appear to be required to assure a reasonable continuum of uniformly plasticized nitrocellulose binder in a propellant containing 45% or more of combined crystalline oxidizer and powdered metal fuel. Such a continuum of binder is necessary to assure acceptable mechanical properties and reproducible burning characteristics of the finished propellant. Preincorporation of a certain content of the water-insoluble solids within the nitrocellulose microspheres is an effective means of helping to assure this continuum of binder and alleviates the requirements for extremely small ball size. The use of a total of 45% or more of crystalline oxidizer and (generally) metal fuel is essential if the propellant is to be competitive with other modern propellants now in service. 

Pesticides and Fungicides. Modern pure food regulations require that the food processor be responsible for their finished products. Since so many pesticides and fungicides are used in agriculture, their detection and quantitative analysis are difficult (5, 22). Organophosphorus and chlorinated hydrocarbons are the most common pesticides. When GLC is used for halogens, electron capture or microcoulometric detectors are used for phosphorus, a thermionic flame photometric detector is required. 

Most diallyl phthalate compounds are used in critical electri-c.il/clcctromc applications requiring high reliability under long-term adverse environmental conditions. Compatibility with modern electronic finishing technology, such as vapor phase soldering, is inherent in these materials. 

PAPERMAKING AND FINISHING. One of the most important factors in the progress of civilization has been paper, a thin flat tissue composed of closely matted fibers obtained almost entirely from plant sources. In modern life paper finds a variety of uses, for writing, for containers, wrappers, wall covering, and—perhaps most important—in all forms of printing newspapers, magazines, books. 

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