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METALWORK & FINISHING – A SUMMARY
The initial rough finishing stages include the mould knockout, FETTLING and blasting (or pickling). If fine finishing is done in the artist’s studio, it is usual to ask for the cast be supplied as a CAST & FETTLED job.
The process of fine finishing is known as CHASING. Chasing involves the removal and making good of runner and riser stubs (SIGHTINGS). The chaser also repairs any casting faults and blends back welded seams in keeping with the local textures on the cast.
Internal and external support structures may need fixing to the cast if the artwork is unable to adequately self support or locate itself. Supports and ARMATURES should be carefully planned in advance, be suitably well constructed and then approved by a competent authority such as an engineer. The inclusion of additional services, which can include pipe work and electrical conduit, should allowed for if these are required - as should access to the interior for painting on protective coatings and tightening of fixings.
WELDING is the principal means of joining separated sections of metal artwork. A suitable welding process with a matching filler metal is used by the founder to achieve an strong joints in cast sections. TUNGSTEN ARC GAS SHIELDED welding (TAGS, often referred to as TIG), is considered the best overall process for joining and repairing NON-FERROUS casts.
Bolting, rivetting and other types of fixing may be used, either instead of welding, or sometimes as a secondary safety feature for reinforcing welded sections. In some cases fixings may be kept in full view to become an important visual feature in the overall design.
POLISHING and PATINATION are the two principal surface finishes for art and design casts. Polishing is achieved through the application of an abrasive ROUGE and fine polish medium via a revolving cloth wheel. Alternatively, an ELECTROCHEMICAL POLISHING process may be be used produce a polish over on a refined metal surface. Patination is the application of a prepared chemical compound(s) to a metal surface using a variety of techniques (heat, fume, immersion etc). Patination develops the cast’s surface and evolves to a compound specific colouring. Patinated and polished surfaces can be protected with either a WAX or LACQUER coating.
Alternative finishes on cast works include gilding, electroplating, enamelling and painting. These can be suitable for application either as a decorative finish, a protective coating, or both.
The artist’s choice of finish is best made well in advance of application to the sculpture. Test samples can be useful, but only as an approximate guide to the final result. If asked, founders will often be able to offer informed suggestions on suitable patinations and other finishes for a sculpture. It is quite usual for the eventual finish on a cast to result from a collaboration between the artist and the founder. It is preferable for the artist to be present in person during the application of a patina to their sculpture cast.
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