As you know, Paul's been working a lot of hours lately. They were making a special type of glass for a customer. I think they had three solid weeks of production of the special glass, which they are finished with, and now they're playing catch-up to restock their regular product in the warehouse.
Paul brought home some squares of the glass they produced. The regular glass has a bluish-greenish tint to it. The special order was called "crystal clear" and it has a greatly reduced iron content. Iron gives glass its green hue. The customer was using it in producing solar energy - obviously, the clearer the glass, the more light can pass through, the more energy produced, etc.
I thought I'd tell you a little about how glass is made where Paul works. Obviously, this is just a general idea from what he's told me and from touring the plant myself (and a bit from a cheat sheet he brought home for me).
The main raw materials used to make glass are sand (silica), soda ash, limestone, dolomite, salt cake, carbon, and rouge (which contains iron). They are mixed in what is called a "batch charger" and move into the furnace where they are heated to around 1500 degrees Celsius. There is the melter (where the materials melt) and refiner furnace (where bubbles and "seeds" are eliminated), which then feeds into the "tin bath". The glass floats on top of molten tin where it is stretched with machines to the proper width and thickness (much like taffy). When it reaches the end of the tin bath it is lifted out rollers, and gradually cooled in the "Lehr hall". There is also a coater at the tin bath exit which coats the glass, if required. The plant can produce E2, TCO, and now EPS coatings. As it heads from the furnace to the "cold end" (where Paul works), it is inspected for flaws both mechanically and manually. Then it is cut into the specified sizes. Automated stackers pick up the "lites" from the rollers and stack them in racks. Then fork trucks pick up the racks and move them to the warehouse. At various points along the line "piano keys" can drop any defective glass or "scraps" into the cullet crushers below. The "cullet" is then crushed and returned to the top of the furnace to be re-melted and reused.
That is a very general run-down of what happens at Paul's work. Paul proof-read this and corrected my mistakes in how the process works. It is very interesting (and kind of amazing) to see in person. If you're ever in the area, I'd encourage you to stop by and ask for a tour of the plant. You get to wear a hard hat, goggles, and a sexy orange safety vest.