Mirror Blanks, 20 Inch and 24 Inch

[Brettstar6754]

For sale, 24 inch or 603mm dia, 40mm thickness glass blank. Was used as a optical flat in an industrial machine.The back has a small notch near the edge. This means a nice bevel of 20mm will be required to remove the notch for perfection. It has been ground to a radius for a dobsonian telescope. F/D= 4.5 Go figure.
$800

For sale 20 inch or 490mm Dia, 40mm thickness Pyrex blank. was a great mirror for years until i chipped the front face with 3 conchoidal chips. they are no deeper than 4mm so the blank can be easily re ground. Or the back could be ground as its in good order.
$600

Swap for quality 100mm refractor?

[koputai]

Hi Brett,
In relation to the 24, do you know what sort of glass it is?
Also, you say there's a notch on the back that could be bevelled off, is the front surface in good condition?

Cheers,
Jason.

[Brettstar6754]

Re 24 inch,

The front is perfect,

The type i dont know for sure, Lime Soda perhaps? its from an optical machine and was front aluminised as a huge plane mirror.
hope that helps. Brett

[astropolak]

Pm Sent