The basic setup I use for casting bells. Here are some notes on my methods and reasoning: *I use only #876 silicon bronze for my bell castings (90% Cu, 4.5% each Zn and Si). This alloy gives a clean casting and a clear, long lasting sound. *The ram is a double-rollover. The cope is rammed first, with the sprue and riser rods in place. *After ramming the cope, flip and ram the drag section, using an inserted iron anchor for the greensand core if necessary. *After ramming the drag, flip again. *Cut the pour basin on the sprue and a tapered basin for the riser. *Rap the riser rod to firm the sand around the pattern. *Separate the flask sections. *Remove the bell pattern. *Hand-cut the drag section step-gate. *Vent the drag sand, going through the greensand core at several spots. *Close and pour. Allow the casting to cool completely in the sand before shakeout. The reason for the bottom step-gate of the pattern is less chance of sand wash during the pour. The riser section is used mainly to allow a more uniform solidification of the bell portion, giving a better sound to the bell. I usually use a longer superheat for bell pours than would be necessary ... seems to give a better sound to the cast bells. All of my bell castings have been 15 pounds or less, but the same setup should apply to larger castings.
The following two books conatain many formulae and techniques for applying patina to different metals and alloys. Both books are available through Centaur Forge Ltd.
METHODS FOR MODERN SCULPTORS Young & Fennell ISBN 0-9603744-0-X
CONTEMPORARY PATINATION Young ISBN 0960374418
Centaur Forge Ltd. 117 North Spring St. P.O. Box 340 Burlington, WI 53105-0340 1-414-763-9175 FAX 1-414-763-8350
The following company offers many ready to use patina solutions for iron and copper alloys to achieve many effects.
JAX Chemical Company, Inc. 78-11 267th Street New York, NY 11004 1-718-347-0057
When coloring metals, the surface must be ultra-clean. I use acetone or similar solvents to remove all traces of waxes and oils ... don't touch a cleaned piece with your bare hands; wear clean cotton gloves ... rubber gloves tend to leave imprints.
The surface finish of the metal will effect the color of the patina. Using the same chemistry, completely different colors can be achieved on polished and blasted metal.
I do a lot of restorations and reproductions and therefore have to match some pretty odd colors/effects. Many of the techniques I employ use common household chemicals and a big propane torch. Experiment and keep lots of notes ... surface finish of the metal, temperature, concentration of the chemistry, time of reactions ... all are important factors.
The following company has a wide selection of blasters, blast media and resist materials ... Truman's Inc. 7075 Route 446 P.O. Box 649 Canfield, OH 44406 1-800-321-9260 (orders) 1-216-533-3384, Ext 22 (techincal questions) FAX 1-216-533-2876 They offer very quick service and the phone people know their products. They also handle a wide selection of spray painting and buff/polish equipment and compounds.
Always wear leather boots in the foundry area (no low-quarters or canvas allowed).
Always wear full face protection (face shield) while handling any molten metal.
No butane cigarette lighters allowed in foundry or welding areas.
If a metal trough/mold is used to pig metal, make sure it is absolutely dry before a pour. Even a film of condensation on a humid day can have explosive results when contacted with molten metal. (Worst burn I have ever had was caused by a drop of my sweat dripping into a pig mold during a pour. The resulting shower of bronze BB's was like a landmine going off.)
I would appreciate it if more folks would send me feedback on what is presented here on this website. Please send me tips and techniques you have used, supply sources and web-links. Thanks ... Winston