WCO Explanatory Notes reproduced for reference. © World Customs Organization. Verify against official WCO publication.
25.20 - Gypsum; anhydrite; plasters (consisting of calcined gypsum or calcium sulphate) whether or not coloured, with or without small quantities of accelerators or retarders. 2520.10 - Gypsum; anhydrite 2520.20 - Plasters Gypsum is a natural hydrated calcium sulphate generally white and fiiable. Anhydrite is a natural anhydrous calcium sulphate used in the manufacture of sulphuric acid or of certain types of plaster. Plasters consist of gypsum partly or completely dehydrated by calcination. The characteristic of gypsum is that, when calcined, it loses part of its water thus forming plasters which on being mixed with water set hard. In order that the plasters should not set too quickly small quantities of retarders are often. added to the calcined gypsum. For s ecial oses gypsum is calcined until all its water xs lost, and a small quantlty of an acce erator suc as alum is added (Keene's cement or English cement). Similar lasters are made by adding alum to natural anhydrite. All these prepared plasters remain in this eading. P pW: R This heading also covers : (1) Plaster reduced to a floury consistency for use in dressing woven fabrics or surfacing paper. (2) Plaster containing added colouring matter. (3) Plaster which has been specially calcined or finely ground for use in dentistry, whether or not containin small quantities of accelerators or retarders. This heading does not include preparations or use in dentistry with a basis of plaster (heading 34.07). f
1.- Except where their context or Note 4 to this Chapter otherwise requires, the headings of this Chapter cover only products which are in the crude state or which have been washed (even with chemical substances eliminating the impurities without changing the structure of the product), crushed, ground, powdered, levigated, sifted, screened, concentrated by flotation, magnetic separation or other mechanical or physical processes (except crystallisation), but not products which have been roasted, calcined, obtained by mixing or subjected to processing beyond that mentioned in each heading. The products of this Chapter may contain an added anti-dusting agent, provided that such addition does not render the product particularly suitable for specific use rather than for general use. 2.- This Chapter does not cover : (a) Sublimed sulphur, precipitated sulphur or colloidal sulphur (heading 28.02); (b) Earth colours containing 70 % or more by weight of combined iron evaluated as Fe O 2 3 (heading 28.21); (c) Medicaments or other products of Chapter 30; (d) Perfumery, cosmetic or toilet preparations (Chapter 33); (e) Dolomite ramming mix (heading 38.16); (f) Setts, curbstones or flagstones (heading 68.01); mosaic cubes or the like (heading 68.02); roofing, facing or damp course slates (heading 68.03); (g) Precious or semi-precious stones (heading 71.02 or 71.03); (h) Cultured crystals (other than optical elements) weighing not less than 2.5 g each, of sodium chloride or of magnesium oxide, of heading 38.24; optical elements of sodium chloride or of magnesium oxide (heading 90.01); (ij) Billiard chalks (heading 95.04); or (k) Writing or drawing chalks or tailors' chalks (heading 96.09). 3.- Any products classifiable in heading 25.17 and any other heading of the Chapter are to be classified in heading 25.17. 4.- Heading 25.30 applies, inter alia, to : vermiculite, perlite and chlorites, unexpanded; earth colours, whether or not calcined or mixed together; natural micaceous iron oxides; meerschaum (whether or not in polished pieces); amber; agglomerated meerschaum and agglomerated amber, in plates, rods, sticks or similar forms, not worked after moulding; jet; strontianite (whether or not calcined), other than strontium oxide; broken pieces of pottery, brick or concrete.