Earlier quoted context omitted.
The disk break...I guess because it has high thermal resistance. You make telescope optics? For fun or work? or both?
Just a hobby at the moment. Working on a 300 mm mirror right now.
That awesome dude. I got into amateur astronomy about two years ago when I first moved to the bay area from new york. I just purchased a celestron nextstar 4SE can't wait to test it out.