Pigments requirements

I have been advised that exposure to sun must be avoided at all costs for a period of 6 months. No sunbathing is permitted for 6 months. To do so would encourage blotchy skin pigmentation requiring further treatment. 

Ceramic Method. Mixtures of barium carbonate and iron oxide are reacted at 1200-1350 °C to produce crystalline agglomerates which are ground to a particle size of ca. 1 pm. This method is only suitable for the high-coercivity pigments required for magnetic strips [5.35],... 

Nacreous pigments require transparent or at least translucent binders or other carriers. Formulations with other pigments have to take their transparency and color mixing rules into account. Producers specify certain product lines for specific applications on the basis of national regulations and technical considerations. They also provide handling guidelines and starting formulas. 

For a successful incorporation of a pigment into the latex particles, both type and amount of surfactant systems have to be adjusted to yield monomer particles, which have the appropriate size and chemistry to incorporate the pigment by its lateral dimension and surface chemistry. For the preparation of the miniemulsions, two steps have to be controlled (see Fig. 14). First, the already hydrophobic or hydrophobized particulate pigment with a size up to 100 nm has to be dispersed in the monomer phase. Hydrophilic pigments require a hydro-phobic surface to be dispersed into the hydrophobic monomer phase, which is usually promoted by a surfactant system 1 with low HLB value. Then, this common mixture is miniemulsified in the water phase employing a surfactant system 2 with high HLB, which has a higher tendency to stabilize the monomer (polymer)/water interface. 

The dyes are vatted in the usual way and added to the dyebath, which is then adjusted to pH 10 by the addition of sodium bicarbonate, and the dyeing is carried out at 95°C (203°F). Oxidation of the pigment requires treatment with sodium percarbonate or perborate at 95°C (203°F) because the action of atmospheric oxygen is slow. The vat dyes offer an opportunity to dye a limited range of shades of excellent all-round fastness. 

In conclusion, spectroscopic methods usually permit crude identification of pigments in an extract, but in most cases, the specific composition remains obscure. Therefore, obtaining details on the composition of a mixture of pigments requires additional analyses, which often involve separation of the mixture into its components using methods such as chromatography. 

Fillers must be free of sulfur-containing impurities, iron, and zinc. In order to minimize reduction in clarity, fillers should have a fine particle size and an index of refraction close to that of the PVC resin. If opacity is desired, however, high refractive index fillers such as talc or calcium carbonate can be used to minimize the amounts of the more expensive titanium dioxide opacifying pigment required. 

This is a two flux model and it has been found of value when calculating the reflectance of a layer containing a mixture of components. Computer programs that use this approach have found practical application in predicting the amounts of pigment required in a layer to match the colour of a standard material. 

Formation of bile pigments requires oxidative ring-opening... 

The pigments required for a specific color tone are intensively mixed with powdered plastic using dispersants (waxes), then dispersed in a twin-screw extruder (high energy consumption) and thereby embedded in the plastic. Laboratory mixtures and production often show different results. 

A leaf on a blackberry plant suffering from chlorosis. Chlorophyll, the green plant pigment, requires nitrogen, magnesium, and iron from the soil. Deficiencies of any of these nutrients cause chlorosis, a condition of low chlorophyll content, indicated by yellowing of the leaves. 

The minimum amount of zinc dust pigment required to provide cathodic protection depends on several factors, including Zn particle size, nature of the vehicle, and the amount of ZnO and other pigments that may be present [6], It probably also depends on the extent to which insulating coatings form on zinc particles before the paint is applied (age of paint). 

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