Colour lakes are preparations insoluble in water, obtained by fixation of natural colouring matter (animal or vegetable) or synthetic organic colouring matter (whether or not soluble in water), on a base, generally mineral (barium sulphate, calcium sulphate, aluminium oxide, China clay, talc, silica, siliceous fossil earth, calcium carbonate, etc.).
The fixation of the colouring matter on the base is usually obtained by :(1) Precipitating the colouring matter on the base with precipitating agents (tannin, barium chloride, etc.), or by co-precipitation of the colouring matter and the base. (2) Dyeing the base with a solution of the colouring matter. (3) Intimate mechanical mixing of an insoluble colouring matter with the inert base. Colour lakes should not be confused with certain other products such as synthetic organic colouring matter, insoluble in water, in which the mineral elements are a constituent part of the molecule, for instance synthetic organic colouring matter rendered insoluble in the form of their metal salts (e.g., the calcium salts of sulphonated dyes, and the salts of basic dyes with complex acids of phosphorus, molybdenum and tungsten) (heading 32.04). Colour lakes are mostly prepared from synthetic organic colouring matter (heading 32.04) with a high resistance to oxidation, such as azo dyes, vat dyes derived from anthraquinone, or alizarin dyes. These lakes are used mainly for manufacturing printing inks, wallpaper and oil paints. Colour lakes may also be prepared from organic colouring matter of animal or vegetable origin (i.e., those of heading 32.03). They include, inter alia, cochineal carmine lake, generally obtained by treating an aqueous solution of cochineal extract with alum, and used mostly in the manufacture of water colours, and for colouring syrups, confectionery or liqueurs; logwood, yellow wood and redwood lakes, etc. These products are often in the form of powders. The heading includes concentrated dispersions of colour lakes in plastics, rubber, plasticisers or other media. These dispersions are usually in the form of small plates or lumps and are used as raw materials for dyeing rubber, plastics, etc., in the mass. The heading also includes certain other preparations based on colour lakes of a kind used for colouring any material or used as ingredients in the manufacture of colouring preparations. However, the preparations referred to in the last sentence of Note 3 to this Chapter are excluded. The heading does not cover Japan (or Chinese) lacquer (heading 13.02).
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