< AUTOGRAPH BRONZES
FINE FINISHING
Although some casts are finished by the artist away from the foundry, the vast majority are taken to completion ‘in house’. The fettled cast is passed on to a fine finisher, whose job it is to make good surface defects and any remove evidence of assembly attachments, including runner sightings and the residual holes left in the cast by removed core pins and vents. Fine finishing in art foundries is done by either a CHASER (small scale sculpture) or a CHASER-FITTER (larger scaled sculptures, which are often made up of several sections).
If the artist’s original MASTER PATTERN is available to the chaser, the metal cast can be compared and checked for any discrepancies which may have arisen between wax working and fettling. This process of cross-checking ideally continues throughout fine finishing, emphasising the importance of [the artist] creating a good quality master pattern in the studio. The chaser, who may not have previously viewed the work, can then execute a true and accurate likeness of the original design.
Any sighting stub on the cast’s surface (residual runners, risers, drains and other attachments), is blended back to continue the local surface detail across this disfigured area. The chaser uses a combination of mechanical and manual tools, including power/air driven die grinders, power chisels and ‘chisel like’ MATTING TOOLS which are fashioned from tempered tool grade or silver steels – all of these tools can be used to recreate surface textures on a cast. Many of the air and other power tools used for chasing have interchangeable cutting faces to accommodate variations in the cast’s surface texture.
Holes left in the metal cast from fettled core pins and support bars are also made good. Traditionally, holes were plugged by DRILLING and TAPPING the aperture with a coarse THREAD, before selecting a suitable section of scrap runner which could be turned down and cut with a matching thread (using a DIE CUTTING tool). This and other time consuming methods of MAKING GOOD are now rarely used in modern art foundries, having been largely superseded by gas and arc welding processes.
In addition to core pin holes and runner stubs, cast works occasionally show evidence of damage incurred as a result of casting faults. Though undesirable, and preferably avoided, casting faults are an occasional fact of life for any art founder (who rarely, if ever enjoys the luxury of being able to make a speculative ‘test cast’ to fine tune the production process). Instead the founder has to rely on long experience to avoid excessive casting faults.
To what extent a faulty cast can be acceptably repaired is a rather subjective issue, dependent upon many factors including the complexity of the design, the ease by which the cast alloy can be worked and made good, the individual skills level of the chaser who has to repair the work, and finally (but not least), the opinion of the artist who’s work is affected. Provided a skilled chaser is available, a fine art casting will usually only be reected out of hand when it is assessed to be more expensive to repair than recast.
The following few pages briefly describes some of the typical casting faults that can arise, together with their usual causes and suggested remedies.
CASTING FAULTS 1 >
|
