Color of pigments

Students will use colored chemical solutions to determine the outcome of mixing particular colors of pigments. 

Color Charts. The colors of pigments can be routinely measured by visual comparison with color charts like the one issued by the Munsell Color Company. This method may achieve a high precision because of the eye s sensitivity to small (relative) color changes. Of paramount importance for reliable application is a uniform light source. The major drawback of the method is that the resolution of color assignments is limited by the resolution of the color chips (see 3.2.3). Interpolation between chips is possible in principle, but difficult in practice as it has to be done in a three-dimensional space. 

SAUNDERSON, J. L. (1942) Calcnlation of the color of pigmented plastics. Journal of the Optical Society of America, 32, 727-736. 

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. 

M. D. Read and K. Mulka in Effect of post-consumer high-density polyethylene on the color of pigmented resin formulations, ANTEC 92, p. 1295, 1992. 

Not all carotenoids are hydrocarbons Oxygen containing carotenes called xantho phylls which are often the pigments responsible for the yellow color of flowers are espe cially abundant... 

Because of the high melt viscosity of polyolefins, normal spinning melt temperatures are 240—310°C, which is 80—150°C above the crystalline melting point. Because of the high melt temperatures used for polyolefin fiber spinning, thermal stabilizers such as substituted hindered phenols are added. In the presence of pigments, the melt temperature must be carefully controlled to prevent color degradation and to obtain uniform color dispersion. 

FWWMR Finish. The abbreviation for fire, water, weather, and mildew resistance, FWWMR, has been used to describe treatment with a chlorinated organic metal oxide. Plasticizers, coloring pigments, fiUers, stabilizers, or fungicides usuaUy are added. However, hand, drape, flexibUity, and color of the fabric are more affected by this type of finish than by other flame retardants. Add-ons of up to 60% are required in many cases to obtain... 

The color of red meat depends on oxygen. The color of the meat pigment myoglobin is purple. The bright red color of the fresh-as-cut meat is from oxymyoglobin. To preserve red meat, the objectives are to retard spoilage and weight loss, and to deUver red color at the consumer level. 

Melanin Drying. One development (ca 1993) in hair coloring involves the formation of pigments within the hair that are very similar to natural melanin. Thus either catalytic or air oxidation of 5,6-dihydroxyindole [3131-52-0] can be effectively used to permanently dye hair within a short time (38). The formed color can, if required, be further modulated with dilute H2O2 or can be even totally removed from hair by this oxidant. 

The intense blue color of Pmssian Blue is attributed to electron transfer between the [Fe(CN)3] and Fe(Ill) ions. A related pigment called Berlin Green is obtained by oxidation of Pmssian Blue. It is thought that the intense color of this other compound results only if oxidation of the [Fe(CN)3] units is incomplete and some remain as hexakiscyanoferrate(4—). The compound in which only h on(Ill) is present, Fe[Fe(CN)3] [14433-93-3], is brown and is subject to autoreduction processes. 

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