FRJ wrote:old glass...I'd like to know more about that if you would elaborate.
No prob. It has to due with purity, and the uniform thickness.
There was a time in history where our ability to "throw light" was not keeping up with technology. This was often seen in lighthouses and on locomotives. Since they did not know how to make superior parabolic reflectors and lights, they just made glass more pure.
From our American Civil War to about 1901 they produced what some of us call "glaziers glass." It's made from the same materials, just superior. In fact, if you look at old farm houses, the windows look cloudy and wrinkled. My glass looks like it was made yesterday. Even from the side you can clearly read newsprint.
When you do your final polishing, you want your mounts, or media or paper to match the bevel perfectly. In doing so you also polish off the last vestiages of any minor burr or wire edge. And nothing--nothing--is as flat and uniform as period antique glass.
Aluminum peens or "dishes." Many serious polishers have special mounts made from something like steel. I've heard but have not seen granite being used. There are now guys who use chocera stones at 30K grit to avoid the process altogether.
For me, I like 7000 grit papers, fine polishing paste and antique glass. But again, take my suggestions with a grain of salt. Do some experimenting. YMMV.
As for my glass, don't bother asking, I'll never sell any of it. I do know that it can be found at flea markets. I know a flint-knapper who makes "crystal blades" from old thicker lanterns, and he found a slab at a flea market.