Sand Cast Bronzes

Casting sand and retainer halfsThe sand cast method of making bronzes has been in use since 1818  In this process of casting, the artist's original clay or wax model is cut into separate pieces thus destroying the original. These parts can vary be from just a few, encompassing the base, legs, and body, to as many as 50 or more individual pieces that are cast separately and assembled  The pieces of the artist's original work are covered in a slurry which is made to be separated easily.  After drying the mold is separated and the original pieces are removed.  A bronze master model is then poured. The individual pieces are chased to remove any unwanted lines and marks and the places where the parts join together are worked until an almost seamless fit is achieved. This master model will be used to create the bronze edition. The individual parts of the master model are pressed into large casting sand blocks. A second block is fitted over the first one and pressed. The blocks are separated and the master model parts are removed. Spues and vents are cut into the sand for the bronze to flow evenly to all of the individual parts in the sand mold and allow the hot gasses to escape. A slurry or sand core is placed to take up the center of the larger pieces so that very little bronze is required. The sand blocks are reassembled and strapped tightly together.  Molten bronze is then poured into this casting block. When cool, the blocks are separated and the parts of the sculpture are removed from the sand, the core pieces are removed by shattering them with a chisel and hammer.  The individual parts have the spue and vents sawed off and the rough places are hand chased and filed. The individual parts of the bronze are assembled and pinned or bolted together.  This must be repeated for each bronze cast.  This process can be done for about 15-20 casts before the master model starts to lose detail and needs to be refreshed by hand chiseling the details back into the master model. Most of the bronzes cast in France in the 19th century were made using the sand cast method. This method was usually used for large editions as the process of making and maintaining a master model in good condition were very expensive and time consuming but production of many bronzes could be accomplished quickly.

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