The Resin Bonded Sand Process

The two essential ingredients utilized in the resin bonded sand molding process is the combination of fine fused silica sand and a typical resin. The sand mold is made or "rammed" upon a stable pattern usually made of wood, plaster, hard plastilina, or wax. *Note* the wax in this case is not burnt-out. When the resin hardens the silica grains, the mold is "parted" or removed from the pattern in sections. Therefore "drafting" is very important to this piece mold process.

The molding material is pliable (via the combination of sand, resin body, and catalyst by weight) only for a short period of time. There are however, resins that are "stretched" or will not harden until after a specific time period has elapsed. If you need more working time ask for a resin which sets only after a longer period. Timing is everything with this process. All patterns and flasks should be prepared and quality control checked before ever mixing the resin and sand. Once a side hardens its impression is there for good.

Simple or two sided "sandwhich" molds are great for such uses as cast metal plaques and ornaments. I have made bonded molds with as many as 18 pieces all fitting back together like a puzzle. This is the beauty of using a resin to bond the refractory silica sand. Once hardened the mold sections can be moved flipped and resized for "cores", "keys", and preperation for casting.

I have poured as much as 1,000 lbs of bronze into a single mold. The wall thickness of the mold itself can be adjusted thicker to handle the force of large metal pours.

Detailed questions about resins and set times can be aquired from Ashland Chemicals Inc.

Be sure to follow all MSDS sheets for proper storage, disposal, and safety hazards, that are part of this process.