Uses of Dyes

The use of dyes for coloring is becoming more popular because of the almost infinite range of colors that can be produced. Moreover, dyes do not need to be electrically deposited. Anodized parts are simply placed in a heated dye solution until the pores become saturated with the pigment (see Dyes... 

The use of dyes having dichloiottiazine groups is rather limited because the reactivity of this group is so high that the stabihty of the dyed fiber as well as that of dyestuff itself is not satisfactory. 

The past experience of the dyestuff industry in its use of dye intermediates such as ( -naphthyl amine and benzidine (4), known human bladder carcinogens (334—343), have led to studies as to whether or not handlers of dyes are exposed to medical ha2ards such as cancer, dermatitis, and other disorders (344-360). 

Visual identification prior to failure is difficult due to the typical tightness of stress-corrosion cracks. A low-power hand lens will greatly aid determination. Crack enhancement may be achieved through the use of dye penetrants. Severe cracking may be detectable using ultrasonic, radiographic, or acoustic emission techniques. 

The traditional use of dyes is in the coloration of textiles, a topic covered in considerable depth in Chapters 7 and 8. Dyes are almost invariably applied to the textile materials from an aqueous medium, so that they are generally required to dissolve in water. Frequently, as is the case for example with acid dyes, direct dyes, cationic dyes and reactive dyes, they dissolve completely and very readily in water. This is not true, however, of every application class of textile dye. Disperse dyes for polyester fibres, for example, are only sparingly soluble in water and are applied as a fine aqueous dispersion. Vat dyes, an important application class of dyes for cellulosic fibres, are completely insoluble materials but they are converted by a chemical reduction process into a water-soluble form that may then be applied to the fibre. There is also a wide range of non-textile applications of dyes, many of which have emerged in recent years as a result of developments in the electronic and reprographic... 

The use of dyes seems to have began over 10 millennia ago, when dyes of vegetable origin were apparently applied to the skin simply for amusement, for ritual purposes, or to identify or differentiate status or social group. All the dyes used in the past and up to the nineteenth century, when artificial dyes were first synthesized, were of natural origin most were extracted from plants, some from animals (Verhecken 2005). Common dyes well known since antiquity are listed in Table 92 (Kirby 1988 Celoria 1971). 

Gordon, P. F. Gregory, P. Non-Textile Uses of Dyes. In Developments in the Chemistry and Technology of Dyes Griffiths, J., Ed. Critical Reports on Applied Chemistry, Vol. 7 Blackwell Oxford, 1984 pp 67-77. 

Cyanine dyes also are used as labels for oligonucleotide probes. Unlike the hydrophilic cyanine dyes valuable for protein labeling, the use of dye-phosphoramidite compounds to synthesize DNA or RNA probes typically requires the use of more hydrophobic dye structures to make them compatible with the solvents and reactions of oligonucleotide synthesis. Thus, indol cyanines containing few or no sulfonates are used in these applications to label oligos for applications such as array detection, hybridization assays, and RT-PCR. 

Masking the appearance of baits and enhancing their specificity by the use of dyes — although some birds in Australia seem to prefer green-dyed meat baits... 

Statham, M. 1989. The use of dyes in bait for wallaby control. Austral. Wildl. Res. 16 421-424. 

As shown in Table 1 the wastewater limit for chromium is 0.5-1 mg/L and Cr is 0.1 mg/L. While conventional 1 2 and 1 1 dyes permit chromium concentrations in the dyebath at the end of the dyeing process of 3.0-13.0 mg/L Cr, the application of modem dyestuffs and optimized processes permits final concentrations to approximately 1 ppm. By general optimization of the process (e.g., dosage of acid), use of dyes with a high degree of exhaustion, and minimal concentration of free chromium [15], final bath concentrations below 4 ppm can be reached, even for black shades. By application of such procedures the exhaustion of the chromium should reach values of better than 95% of the initial value. 

Procion Rubine MX-B, Procion Yellow H-A, and Turquoise MX-G. These dyes have found use over the last few decades in the purification of a broad range of proteins and enzymes, including albumin, decarboxylases, glycolytic enzymes, hydrolases, lyases, nucleases, oxidoreductases, synthetases, and transferases [77,78], The first use of dye-ligand affinity chromatography was described by Staal et al. in 1971 [79], Since that time, it has become an extremely popular tool for enzyme and protein purification, with hundreds of such compounds having been isolated by this technique [3-6,76-79],... 

Figure9.8 The absorbance of 1.05 x 10 M pinacyanol chloride at 610.0 min pH 9.59 sodium borate buffer (I = 0.1) at 50 °C vs. dodecanoate concentration. The absorption spectrum of pinacyanol chloride in aqueous solution of anionic soaps changes sharply to one characteristic of its solutions in organic solvents within a small range of soap concentration (X ax 610 nm). This effect is attributed to the formation of micelles, in whose hydrocarbon-like layers or cores the dye is solubilized. The concentration of soap at which this spectral change occurs is taken as the cmc. The use of dyes for the determination of cmc values may lead to micelle formation at a concentration below the true cmc. In practice, the method gives only a rough approximation of the cmc. (Adapted, with some modifications, from Corrin et al., 1946.)...

In the years since 1964, when the first passive Q-switching with organic dyes was accomplished, the use of organic dyes in laser technology has become increasingly important. Some of the most important developments in the laser field would not have been possible without organic dyes, and one can foresee even further possibilities for the use of dyes in laser technology which could be realized in the near future. 

A further improvement and more freedom in the choice of laser wavelengths can be expected with the use of dye vapors. In liquids, the phase-matching concentration is set by the requirement that the anomalous dispersion of the dye compensates for the normal dispersion of the solvent. The latter is a new parameter that can be varied at will in the gas phase by changing the nature and partial pressure of the buffer gas. The broader resonances of dyes as opposed to metal vapors, which are sometimes used for this purpose, is an advantage for tunable frequency tripling of dye lasers. Another advantage results from the possibility of working at much lower temperatures than with metal vapors. 

The use of dyeing terms and comments on the technical performances of the dyes have been kept to a minimum and such information should be sought in the many references quoted. Where use of such terms is necessary, a brief explanation has been included. 

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