Inexpensive colorants

The only nitroso dyes important commercially are the iron complexes of sulfonated l-nitroso-2-naphthol, eg. Cl Acid Green 1 [57813-94-2] (78) (Cl 10020) these inexpensive colorants are used mainly for coloring paper. 

Several inexpensive colorants compatible with a wide variety of polymers have a simple chemical structure - they are single metal oxides. For convenience, we have listed the four most commonly used examples in Table 1, along with several properties of interest, such as compliance with food contact applications and cost. 

Iron oxides are used as relatively inexpensive colorants for different hues of red, yellow, brown, and black. These are inorganic pigments that possess good light fastness and are usually chemically stable at higher temperatures. 

Composite Gemstones. Many types of composite or assembled gemstones have been made (1). Some are shown in Figure 3. In the United States a doublet has two pieces combined using a colodess cement. If three pieces are used, or if two pieces are assembled using a colored cement, the gemstone is a triplet. The use of composite stones has declined rapidly with the rise of inexpensive synthetics. Frequendy seen are opal doublets, where precious opal is backed by a black material. In opal triplets a thin sHce of precious opal is cemented between a black backing and a clear cover, usually of quartz. Additionally, insects and even fish have been inserted into amber. 

Effective antistatic agents must act at a relative humidity below 40%, preferably below 15%. The agent must form a film on various surfaces and be apphed from a solution or dispersion in water or other inexpensive solvents. The antistatic agent must not interfere with subsequent processing of the product, impair the hand, or affect color, odor, appearance, and performance properties of the substrate. It should be nontoxic and nonflammable. 

The ancient process of stoving is stiU occasionally used to bleach wool and silk with sulfur dioxide. In this process, wet fabrics are hung in chambers of burning sulfur or sulfur dioxide gas for at least 8 h. The fabrics are then washed with sodium sulfite to remove excess sulfur dioxide. Fabric so treated may have unpleasant odors, and the original color eventually returns, but the process is simple and inexpensive. 

Iron Oxides. In addition to the black iron oxide, there are several natural and synthetic yellow, brown, and red oxides. As a class, they provide inexpensive but dull, lightfast, chemically resistant, and nontoxic colors. The natural products ate known as ocher, sieima, umber, hematite, and limonite. These include varying amounts of several impurities in particular, the umbers contain manganese. Their use is limited because of low chroma, low tinting strength, and poor gloss retention. 

Resins are also used for permanent tooth-colored veneers on fixed prostheses, ie, crown and bridges. Compositions for this application include acryflcs, vinyl—acryflcs, and dimethacrylates, as well as silica- or quartz-microfilled composites. The resins are placed on the metallic substrates of the prostheses and cured by heat or light. These resins are inexpensive, easy to fabricate, and can be matched to the color of tooth stmcture. Acrylic facings do not chemically adhere to the metals and are retained only by curing the resin into mechanical undercuts designed into the metal substrate. They have relatively low mechanical strength and color stability, and poor abrasion and strain resistance they also deform more under the stress of mastication than porcelain veneers or facings. 

Basic dyestuffs are usually used for dyeing of unbleached pulp in mechanical pulp such as wrapping paper, kraft paper, box board, news, and other inexpensive packaging papers. Their strong and brilliant shades also make them suitable for calendar staining and surface coloring where lightfastness is not critical. 

Typical ranges of enamel compositions are Hsted in Table 2. Raw materials (Table 1) for the glass batch include minerals, such as feldspars and quartz, because these are inexpensive sources of Si02 and AI2O2 (see Clays). The batch composition for cover coats is comprised primarily of manufactured chemicals of known, controlled levels of purity to maintain reproducible, clean colors. 

Consider, as an example, the logic of a policy decision to build and locate an electric generating plant or oil refinery. Economic considerations such as the availability of ample and inexpensive land, and social considerations such as zoning regulations and political influence, would play a major role m such a decision. In practice, this makes it more likely that plants and refineries, as well as waste sites and other locally undesirable land uses, will be located in poorer communities whose population is often largely people of color. 

Point-of-use infrared thermometers are commercially available and relatively inexpensive. The typical cost for this type of infrared instrument is less than 1,000. Infrared imaging systems will have a price range between 8,000 for a black and white scanner without storage capability to over 60,000 for a microprocessor-based, color imaging system. 

OLEDs are obviously able to produce light with virtually every color in the CIE chromaticity diagram but the optimum inexpensive method to manufacture a pixeiatcd full color display is not yet established. The difficulty lies in patterning OLED materials with standard photolithographic methods. Five schemes to achieve color have been suggested, as illustrated schematically in Figure 13-19. 

Fratianni, A. et al.. Estimation of color of durum wheat comparison of WSB, HPLC and reflectance colorimeter measurements, J. Agric. Food Chem., 53, 2373, 2005. Papadakis, S. E. et al., A versatile and inexpensive technique for measuring color of... 

Solid phase spectrophotometry proved to be an appropriate technique for the determination of colorants in foods dne to its simplicity, selectivity, reasonable cost, low detection limits, and use of conventional instrnmentation. This simple, sensitive, and inexpensive method allowed simnltaneons determinations of Snnset Yellow FCF (SY), Quinoline Yellow, and their nnsnlfonated derivatives [Sndan I (SUD) and Quinoline Yellow Spirit Soluble (QYSS)] in mixtnres. Mixtnres of food colorants containing Tartrazine, Sunset Yellow, Ponceau 4R, Amaranth, and Brilliant Blue were simultaneously analyzed with Vis spectrophotometry without previous chemical separation. ... 

Get an NMR tube. They are about 180 mm long, 5 mm wide, and about a buck apiece for what is euphemistically called the inexpensive model. The tubes are not precision ground, and some may stick in the NMR probe. This should not be your worry, though. They also have matching, color coordinated designer caps (Fig. 134). 

Papadakis, S.E., Abdul-Malek, S., Kamdem, R.E., and Yam, K.L. 2000. A versatile and inexpensive technique for measuring color of foods. Food Technol. 54, 48-51. 

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