 |  | Small-Scale Horn Processing (ILO - WEP, 1988, 104 p.) | ||
 |  | CHAPTER V. POLISHING | ||
|  | 1. Trimming | ||
| | 2. Sanding | ||
| | 3. Polishing | ||
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To make horn shiny it must be trimmed and polished. The trimming of the convex parts does not present any problems. Wood rasps or coarse sandpaper may be used for this.
Manual scraping with sandpaper is a long and tedious operation. A well-equipped workshop will use a sanding machine, such as that shown in figure V.1, fitted with a supple sanding head and coarse sandpaper discs.
Figure V.1: Sanding machine
Removal of rough areas in concave parts of the horn is a more complex task as rasps and sanding discs cannot reach the hollow parts. Care must be taken to smooth rough areas while the horn is flat, i.e. before bending or stamping.
Sanding of the convex parts of the horn is carried out with sandpaper, in the same way as trimming. Sanding of concave parts of engravings and carvings should be carried out with a scraper, as shown in figure V.2. The scraper can easily be made from woodsaw blade sections.
Figure V.2:
Scraper
The horn is first polished by vigorously rubbing it with extra-fine sandpaper that has first been coated with mineral oil or soap, either manually or with a sanding machine.
A better shine is obtained by vigorously rubbing the horn by hand with a soap-impregnated chamois leather sprinkled with rice-husk powder, which is an excellent abrasive because of its microscopic silica grains. Commercial metal polishes in paste or liquid may also be used.
Polishing by hand, like trimming, is a time-consuming and tedious operation. It can be considerably shortened by using a sanding machine with polishing pads (figure V.3) or felt pads mounted on a bench sanding lathe (figure V.4). For machine polishing, the polishing and felt pads should be impregnated with soap, rice husk powder or metal polish.
Figure V.3: Sanding machine with
polishing pad
Figure V.4: Sanding lathe with felt
pads
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