| Horological hints & tips | June 2002 |
Silvering and lacqueringCleanliness when silvering is an essential requirement.Conservation techniques also inhibit metal removal. Stripping back brass prior to resilvering is not advisable unless surface is so badly damaged or pitted that this is unavoidable. Alternatively, the use of a 'first application' of silvering powder combined with fine pumice powder and a small quantity of washing-up liquid using a clean large flat cork as the rubbing applicator is often beneficial. Do not use in any way an abrasive technique that could damage (round off) the engraved edges. Fine pitting, below surface depth, needs cleaning to remove embedded dirt as such dirt can react with the applied lacquer which invariably causes staining. Engraved wax infill sometimes presents problems. If re-waxing is required, excess wax, whilst still warm, should be removed by a method that does not scratch or mark the engraved brass. Use either plastic I or wooden tipped scrapers. I sometimes use amyl acetate (outdoors only, as this chemical emits toxic vapours) and cotton buds to remove stains and to prevent abrasion. Lacquering invariably presents difficulties in that after all the time and labour expended, the wax infill gradually 'creeps' at the edges of the engraving due to reaction with the lacquer. Some lacquers are particularly aggressive. My method (which I have been perfecting for 30 years) is by using foam as the lacquer applicator. The foam used is of the hard dense type, because the cheaper soft foam will rapidly dissolve and leave a residue on the lacquered plate. The foam is scissor-cut to provide a lacquering edge, evenly charged with lacquer and applied with firm, light and smooth strokes. For example, a 12in round dial can be lacquered within 15 seconds. Speed and accuracy is essential. Obviously the excess foam with surplus lacquer is thrown away. Many acquaintances, some now no longer with us, who used traditional methods most of their working lives, would not initially consider alternative methods. How gratifying to be advised, often after a lapse of several years: 'I'm using foam now'! J N Bartlam, UK |
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