Agglomerated cork is manufactured by agglomerating crushed, granulated or ground cork generally under heat and pressure either :
(1) With an added binding substance (e.g., unvulcanised rubber, glue, plastics, tar, gelatin), or (2) Without an added binding substance at a temperature of about 300 ¨¬C. In this latter case the natural gum in the cork acts as a binder. Agglomerated cork of this heading may be impregnated (e.g., with oil), or reinforced by backing with paper or cloth provided it does not have the character of linoleum or similar materials classified in heading 59.04. Agglomerated cork retains most of the properties of natural cork, and in particular is an excellent heat- or sound-insulating material. In many cases, however, the addition of the binders required for the agglomeration modifies some of the characteristic features of the cork, in particular the specific gravity and the tensile or crushing strengths. In addition, agglomerated cork has the advantage of being suitable for direct moulding to any size or shape. Agglomerated cork is used to make much the same range of products as those referred to under heading 45.03 but, whereas it is rarely used for making stoppers, it is used more often than natural cork for crown cork discs. Agglomerated cork is also used largely, and in preference to natural cork, for building materials such as panels, blocks and tiles, and as moulded shapes (cylinders, shells, etc.), for insulating or protecting hot water or steam piping, for lining petrol pipelines, for expansion jointing in the construction industry and for the manufacture of filters. See the Explanatory Note to heading 45.03 as regards articles excluded from this heading.
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