Glasses for corrective spectacles

70.15 - Clock or watch glasses and similar glasses, asses for non-corrective or corrective spectacles, curved, bent, hollowed or the 1'l fe, not optically worked; hollow glass spheres and their segments, for the manufacture of such glasses. 7015.10 7015.90 - Glasses for corrective spectacles - Other This heading covers : (A) Glass, curved, bent, hollowed or the like, of any shape or size, with or without parallel faces, used as clock or watch glasses; it also includes all similar lasses for photograph frames and the like, medallions, hy ometers, barometers and simi ar appliances. In other words the heading covers a range o glasses of types normally designed to protect the dials or faces of the articles in question, even if in particular cases the glasses are intended for use as laboratory watch glasses or for the manufacture of mirrors. P f When the above glasses do not have parallel faces, they may have certain o tical properties, but whereas the primary functron of the glass elements of heading 70.1 is to produce a required optical effect, the main function of the goods of this paragraph is protection. (B) Glass, curved or the like, for non-corrective spectacles (e-g., sun-glasses and other protective spectacles), i.e., glass generally of poorer quality than used for corrective spectacles. These glasses usually have parallel faces, and are not intended, in practice, for o tical working. Nevertheless, should they be optically worked they would be exc uded (heading 90.01). f The glasses described in Parts (A) and (B) are mainly manufactured by the following processes : (I) Glass is blown into a hollow here of a diameter not usually exceedin 80 cm. This sphere is divided into three or our parts which are in turn cut into smal segments by means of a kind of diamond-tipped compass. The edges of each segment are then turned-in by hot-pressure in a mould. ? f (2) Small squares or discs are cut from flat glass; they are then curved either by softening in a concave mould or revolving ring under the action of heat, or by hot-pressure in a mould. (3) The molten glass is poured directly into the mould of a mechanical press. (4) A cavity is ground in one surface of a piece of round or rectangular (including square) flat glass to provide space for the clock or watch hands. In addition to glasses shaped for use (round, oval or rectangular including square), this heading also covers hollow spheres and segments obtained by the process descrxbed in (1) above. (C) Glass (including blanks, i.e. pieces simply pressed or moulded but not optically worked) for corrective spectacles. In most cases, the corrective spectacle industry uses blanks which are enerally in the shape o!?lass the lens b anks are obtained by cutting processes and then softening these cut blanks. Blanks fiom either source requre before they can be used as correctwe spectacle lenses. B This heading covers blanks for corrective s ectacle lenses, i.e., pieces simply moulded and not optically worked Prior to moulding, $is type of glass falls in beading 70.03, 70.04, 70.05 or 70.06, as appropriate. The heading does not cover : (a) Flat glass for the same uses (headings 70.05,70.06 and 70.07 in particular). (b) Optical elements of heading 70.14. (c) Clock or watch elasses specially pr ared fox laboratory use (pierced in the centre, ground on the edges to ensure autight sealing, ctc.)~ege.ding70.17). (d) Glass for corrective spectacles or contact lenses, optically worked (Chapter 90).