Charles Ponticello and Deep Water Sponger

In June of 2007 OK Foundry had the honor of casting Deep Water Sponger for Richmond local artist Charlie Ponticello to be installed at the Baltimore Inner Harbor for the Baltimore Sculpture Project. Charlie's vision of a mixed media sculpture with a large cast iron figure as the center piece, was the perfect opportunity to try out large format casting of iron using lost foam and resin bonded sand molding. The bulk of the foundry work was accomplished over two weekends at OK Foundry to cast a trunk and torso that were later assembled by Charlie to make the 1,500 lb. cast iron sculpture.

Deep Water Sponger was cast using a production resin bonded sand system (No-bake molding) on a molding line used for daily production casting of industrial and architecural iron castings, but much of the lost foam casting techniques were put into practice for the first time on Sponger. The success of Sponger was in large part due to Charlie's extensive experience with mixed media sculpture and the assistance of Bill Scholl, a master pattern maker and foundry process expert, from Custom Wood and Metal Craft.

This web page and pictorial study is published here to promote the art of casting and give back to those who have so freely offered their knowledge and experience. We would like to extend particular thanks to the folks at Sculpture.net who so freely provided feedback on the technical questions of lost foam casting.

Deep Water Sponger was installed at Johns Hopkins University in September, 2008. See the Johns Hopkins University Gazette, January 5th, 2009

No Bake Molding for Flexibility in Large Format Casting

OK Foundry Company uses a three part phenolic urethane binder system for no-bake molding. The binder system is added to recylced and virgin silica sand using a production sand mixer. The areated and coated sand is used to fill mold boxes and coreboxes for cope and drag molding of iron castings. The urethane binder sets up quickly and makes very hard molds that do not require any other mechanical support to hold the hydrostatic pressure of molten metal in a large casting. Since the resin coated sand does not require compaction to set, delicate foam patterns can be used to form the casting cavity. The resin bonded sand forms the mold interface and structural support for castings made with lost foam. The biggest drawback with no-bake molding and lost foam casting without using ceramic coatings is that the casting surface texture is very rough due to poor sand compaction against the foam pattern and the increased amount of lustrous carbon from the foam patterns.

For both the trunk and torso sections of Sponger, a flat base was first made using a drag molding box to provide a solid foundation to support the sand filled foam patterns. Once the foam patterns were supported and rigged for gates, risers, and sprues; making the rest of the mold was as simple as building a box and filling it with resin coated sand. The most difficult aspect of this process was adjusting the binder ratios to allow enough open working time of the sand and transporting the sand from the mixer to the large floor mold.

Further development of this casting process should include testing of ceramic coatings applied to the foam patterns to control surface texture, adjustment of open time of the binder system, and building conveyance for the sand from the mixer to the floor mold.