Bronze Casting - The Final Shell

The final dip - after ten dips in the silica suspension and the sand - is one last dip in the suspension to make the surface smoother minimize bits of sand falling off. After the final drying (overnight is a good idea), the end of the cup (covered with a lid during the investment to prevent the suspension from getting inside) will be cut off with a diamond or corundum edged cutter.

At that point the mold is heated in a special furnace to 1650 deg Fahrenheit. The wax melts and runs out and any remaining wax inside the shell gets burned out. Also the heat helps harden the shell further.

Not easily visible here was a small mishap during the investment which will be evident after the pour. Also note that the ceramic covering the sprue which attaches the grid to the cup looks a bit thin. This was because that place was a natural place to hold the sculpture during the dipping and so the layers got rubbed down. So at that point the shell is weak but will be strengthened by adding ample "green patch" - a cement like paste - to the shell shortly before reheating the shells just before pouring in the bronze.

If you want to take a slight detour to see the actual bronze casting (which will also open up a new window), then click here. But to forward to see the fruits of the "pour" on this model, just click the NEXT button.