Pigment color differentiation, usefulness

In addition to the many enzyme systems available, there are with each a series of chromogenic substrate solutions that can be used to create different colors and locations of reaction products. For the peroxidase system, there are numerous oxidizable compounds that precipitate as a permanent color. The most common and still widely used is 3,3 diaminobenzidine tetrahydro-chloride (DAB). This compound precipitates to a golden brown color when in solution with peroxidase and hydrogen peroxide. This brown color has many subtleties and readily stands out in a tissue section. With practice, it is possible to differentiate specific from nonspecific staining patterns just by examining the characteristics of the precipitated pigment. This material is also insoluble in alcohol and xylene, and therefore the tissue may be routinely dehydrated and cleared without loss of chromogen. 

The term pigment may best be defined using the definition proposed by the Colored Pigment Manufacturers Association (CPMA), a definition developed specifically to enable differentiation between a dyestuff and a pigment ... 

Over 150 pigment samples covering the spectrum of hues used in Cilician art were taken from the four manuscripts described above. The hues were differentiated both by visual assessment and by comparison with color chips from the Munsell Book of Colors (14). In addition, because both MS Freer 32.18 and MS W. 539 were painted by workshops, pigment samples were taken from all of the miniatures of recognizably different styles in these two manuscripts. 

Our primary objective is to determine whether slight differences in the color of heavily pigmented polymer melts can be successfully differentiated by the Vis-NIR system. We will also briefly examine thermochromic phenomena and the effect of melt temperature on color. Finally, the problem of relating color differences measured in-line to data obtained off-line from the same masterbatch when fully diluted in an end-use resin at room temperature will be discussed. 

As first observed in 1903 by M. Tswett, a Russian botanist, when plant pigments were dissolved in a nonpolar solvent such as hexane and this solution was passed through a glass column packed with calcium carbonate, a separation of the two major forms of chlorophyll occurred due to a differential migration through the packed stationary phase. This observation of color writing led to the most used term in the separation sciences today—chromatography ... 

As with pigments that create a metallic surface appearance, other additives supply additional visual effects meant to draw the human eye to a product and differentiate it from competing products. This may involve simply enhancing the color strength of a colorant, or another colorant may be used to add a deep pearl-like shine to a colored product. Ironically, with the right special-effects colorant or additive, a product made from the most inexpensive of plastics may take on a more high-end visual character. 

Uses Luster pigment for coatings, inks, and plastics Features Available in wide variety of grades differentiated by color, color effect and particle size suitable for high temp, applies. 

In natural fiber identification for animal fibers, careful microscopic observation to assess the following components is important one is the medulla, its structure, continuity, cuticular thickness, and the distribution and color of pigments other important features are those of scales, such as its pattern, shape, margins, and changes. For vegetable fiber identification, polarizing microscopic analysis is also useful for example, fibers that have a Z-type spiral are differentiated from those with S-type spirals. 

The recycled polymer can also be contaminated by pigmented constituents in the feedstock. In the recychng of RDPE bottles by melt reprocessing, a major effort has been directed towards producing a naturally-colored recycle stream. The major barrier to overcome to reach this end is the removal of the colored bottle caps. Typically blue and red caps are used to differentiate the fat contents of... 

Reflectance spectrophotometry is a means for identification of pigments [131]. For qualitative analysis of pigments the log k/S) profiles of the Kubelka-Munk analysis can be used, as their shapes are independent of concentration. The same principles apply to characterisation of colorants on textile fibres. However, identification of dyes on textile fibres by assessment of reflectance curves is difficult owing to the dependence of spectral reflectance on concentration and spectral interference due to the base colour of the substrate itself. Interference due to fibre absorption may be overcome by a differentiation with respect to wavelength, so that the resulting profile generated is a property of the dyestuff alone. 

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