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ART OF STAINED GLASS ZINC CAME Zinc came is made of sheet metal folded onto itself. Therefore, it is not solid, but hollow. It is more rigid that lead, therefore, one might be forgiven to assume that zinc will be more durable. Counterintuitive as it may be, zinc construction is subject to faster degradation from pollutants than lead construction, because of the nature of the metal itself, and because its hollowness means that the pollution has a greater surface to corrode. The expected lifespan of zinc construction is estimated at a single century, while lead construction will outlive it by several centuries. Working with zinc came requires the use of either a hack sack, or an electrical saw. Generally zinc came is reserved for geometric patterns made with straight lines only. Zinc came can be bent using a zinc bender. This is not very easy, so that zinc came projects generally don't have excessive curlicues. Before purchasing a came bender, be aware that each company has its own bender; for instance, zinc came from Cascade Metals needs the Cascade Metals came bender, and zinc came from Chicago Metallic needs the Chicago Metallic came bender. It is also more difficult to patina zinc consistently than it is to patina lead. Zinc came does have the advantage of being about 40% lighter than lead came, and its coefficient of expansion is 7% less than lead, meaning that zinc construction will suffer from less metal fatique when exposed to temperature fluctuations. LEAD CAME Lead came is soft and flexible (a fingernail can scratch its surface), and is traditionally cut with a lead knife, or quite competently with tin cutters. Some glaziers like to stretch the lead before using it, as it firms it up temporarily, and makes it easy to work it. Stretching the lead can also be useful if the lead strip is badly bent or twisted. If you don't mind working with soft lead, and the strips are in good shape, stretching is entirely optional. During the war, lead came was stretched so much for reasons of economy that leaded windows from this period are often weak. Because lead came is made of extruded metal, unlike zinc with is folded sheet metal, lead is solid inside. Lead came with 2% antimony can also be purchased; this alloy is expected to be significantly more durable than pure lead. Lead will develop a nice natural patina during the course of puttying and brushing off with whiting. It is recommended that beginners learn with lead first. BRASS AND COPPER CAMES These came products are specialties generally reserved for restoration work. They are made of extruded metal like lead, but much more rigid. They are enjoyeing a revival in mass production as well. |