The Delft Clay Method is a highly refined form of sand casting that substitutes genuine Delft Clay from Holland for ordinary casting sand. The process was invented by Hans Karreman, a Dutch goldsmith. Delft Clay is much finer than casting sand, providing remarkably sharp and highly detailed castings in gold, silver, copper-based alloys, pewter, etc. Castings require very little finishing work. Once you have cast your piece, the Delft Clay can be re-used. Since this is a cold-molding process, molds can be made from patterns composed of wood, wax, epoxy, plastics, and, of course, metal. Because this is a type of sand casting, it is best suited to producing castings without pronounced undercuts.
A Delft Clay mold is created in these steps:
- Fill and compact the Clay into one half of the aluminum ring frame
- Remove excess clay with a straight edge (e.g. a flexible steel ruler)
- Press your original pattern halfway into the clay.
- Brush talcum powder over this surface of the mold.
- Install the other half of the aluminum ring frame, fill with clay and compact
- Open the ring frame and remove the pattern
- Carve out a pouring channel and vents
- Pour in molten metal