Next week I'm going to give a short talk on metals.... and thought I'd practice some here. I'm not much of a public speaker. I never even threw spit balls from the back of the room. I've always been more of a window gazer, a watcher of sparrows dust and shadows. But. What the heck. I've even found a video of a little fellow that I think if I can channel him, I'll do okay.
I'd like to talk about some jewelry metals. Specifically platinum, gold, and silver. I'll cover a bit on some other materials at the end. Platinum was first described by the Italian humanist Scaliger in 1557. The name platinum came from the Spanish word for "little silver" or "platina del Pinto." It was a bothersome metal the Spanish conquistadors found in the 17th century in the Pinto River of Columbia. Grains of platinum were just tossed in the search for gold. At first platinum could not be melted or refined as platinum requires a high heat 1768.3 °C for melting, and the ability to do that did not evolve until the end of the 1700s.
Platinum is highly useful metal, as it does not corrode or oxidize. Its use in jewelry increased around 1900, and the industrial uses of platinum exploded in the 1970s. At this time approximately 50% of platinum is used in jewelry, and 50% industrial. The industrial applications of platinum include catalytic converters (in cars), smokestack scrubbers, and cancer treatment. Also, WWII bombers used platinum in their spark plugs. Traces of platinum are released into the air with catalytic converters. This is not thought harmful, but the effects have not been studied extensively.
With jewelry, platinum is prized for its durability, resistance to oxidation, and the high finish that can be achieved. When working with platinum you weld, you do not solder. Since platinum needs a much higher heat, the surface of the metal must be clean because if there was gold on the surface you risk pitting the platinum. The gold would melt into the platinum before you ever reached the temperatures needed to work platinum. With sizing a ring, a piece of platinum is pounded paper thin and put between the 2 ends of the ring. The area is then welded, and the thin slip of metal heats up first, melting into the joining parts creating the bond.
The best thing about all precious metals is though the environmental effects of mining and refining are highly dependent on the vigorousness of environmental laws, they define recycling. Every spec of metal is reused.
(I pause before continuing on to gold and silver. Wild clapping erupts. Well, here I'll let Trevor work his magic...)