Pigments, and Soaps

C12O2 is a yellowish (sage) gieen pigment. It has good strength and opacity and excellent stabiUty. It is used ia eye makeup and soap. 

Most vat dyes are based on the quinone stmcture and are solubilized by reduction with alkaline reducing agents such as sodium dithionite. Conversion back to the insoluble pigment is achieved by oxidation. The dyes are appHed by either exhaust or continuous dyeing techniques. In both cases the process is comprised of five stages preparation of the dispersion, reduction, dye exhaustion, oxidation, and soaping. 

Tyj)e of dryer Applicable with dry-product recirculation True and colloidal solutions emulsions. Examples inorganic salt solutions, extracts, milk, blood, waste liquors, rubber latex, etc. Pumpable suspensions. Examples pigment slurries, soap and detergents, calcium carbonate, bentonite, clay sbp, lead concentrates, etc. does not dust. Recirculation of product may prevent sticking Examples filter-press cakes, sedimentation sludges, centrifuged sobds, starch, etc. 

Keune K., Binding medium, pigments and metal soaps characterized and localized in paint cross sections, PhD Dissertation, University of Amsterdam, 2005. 

P.R.2 does not show perfect performance in special applications (Sec. 1.6.2.3) in prints, which is also true for a number of other members of this class. In this respect, P.R.2 is inferior to P.R.112. This may have a particular impact on marginal areas of pigment applicability. P.R.112 letterpress proof prints, for instance, tolerate mineral spirits and soap while P.R.2 prints only reach step 4 on the 5 step fastness scale. P.R.2 specimens are also sensitive to clear lacquer coatings and to sterilization. 

P.R.66, a barium salt, is sold only in the USA. The pigment is also available as an aluminum oxide hydrate precipitate. Its shade is considered a brilliant medium red, which is somewhat yellower than that of the chemically related P.R.67. Commercial types of P.R.66 are very transparent. The pigment is highly sensitive to acid, alkali, and soap. Its fastness to organic solvents is poor, its fastness to overcoating as well. P.R.66 exhibits limited lightfastness. Its main application is in metal deco printing. 

Q Part I List of dyes, colours and pigments permitted in cosmetics and soaps. 

Despite their low (photo)stability, chlorophylls, or rather their derivatives, have found some applications, especially in the nutrition industry. In Europe the food additive E140 is chi, and E141 is chlorophyllin (a semisynthetic sodium/copper derivative of chlorophyll), and they are used in cakes, beverages, sweets, icecream etc. As color No 125 they find applications in toothpaste, as a soap pigment and in shampoos. The older literature also... 

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