(19)

(11)

EP 0 458 828 A1

(12)

(43) Date of publication: 04.12.1991 Bulletin 1991/49 (21) Application number: 90903038.0 (22) Date of filing: 16.02.1990

(51) International Patent Classification (IPC):  C23C 18/ 34( . ) C23C 18/ 52( . ) (86) International application number: PCT/GB1990/000261 (87) International publication number: WO 1990/009468 (23.08.1990 Gazette 1990/20)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB IT LI LU NL SE (30) Priority: 17.02.1989 GB 19890003646 17.02.1989 GB 19890003645 (71) Applicant: POLYMETALS TECHNOLOGY LIMITED London W1R 7PD (GB)	(72) Inventors: McDONALD, Ian, Gerald Eastcote Middlesex HA4 9NE (GB) ARCHER, Philip, John Hampshire PO4 0QR (GB) (74) Representative: Sheard, Andrew Gregory, et al  Kilburn & Strode 30, John Street London WC1N 2DD London WC1N 2DD (GB)