Well I put a bid in for a 10" mirror blank that I thought for sure would be out bid easily and lo and behold, I won the darn thing!
A mirror blank is a 'slab' of glass in a certain diameter, in my case, 10", that you use to make a mirror your self. This slab of glass is flat on both sides and has no parabolic or spherical shape to it. It is basically your job to give it the concave shape you want.
There is a process that, from what I can gather, is time consuming and painstaking. It involves making a 'tool' basically a hard molded plaster replica of the mirror diameter and adhering porcelain tiles on to one surface of the 'tool' which you then use, with the help of special abrasive powders, to grind and 'hog' out the a concave shape to one side of the mirror blank.
You would think that it would take precise and expensive machinery to make a concave mirror, right? Well, it seams that A LOT of people make their own mirrors. Even kids make their own mirrors using this technique. In fact, many telescope clubs offer mirror making classes, one of which I plan to take knowing close to nothing about how to make one save for the tiny bit I mention here.
So I am stuck with one 10" mirror blank. But the good side is that if I DO manage to make this 10" mirror... I will be making a HUGE telescope, relatively, of course.
BTW, my winning bid was wayyy low. I have seen 10" mirror blanks priced at $200+ my bid was under $50.00.. makes you wonder, huh?
So wish me luck.
Thanks for reading.