Telescope Mirror Blanks

Providing telescope mirror blanks and kits in various sizes to telescope makers. Standard mirror blanks are individually tested for internal strain by people who have been making telescopes for a long time



Plastic protractor inserted under a 6 inch mirror blank during a stress test, to illustrate what stress would look like - if there were any present. All blanks test like this, or they don't ship



Mirror Blank Sizes:

We provide mirror blanks from 4 to 14 inches in 3/4 inch thickness, and thicker 1" mirror blanks up to 18 inches in diameter. Stock varies, so please check the Buy Mirror Blanks page to view all mirror blanks.


Why Plate Glass?

As Sky and Telescope Magazine puts it, "the idea that Pyrex telescope mirrors are better than those made from plate glass" is "demonstrably incorrect and may have caused many a telescope owner unnecessary effort, expense, or angst". Simply put, plate glass blanks take on and maintain every bit as accurate a parabola as Pyrex blanks. Read the full Sky and Telescope magazine article here: Plate vs. Pyrex .

Benefits of using thin plate glass mirror blanks?

There are several advantages to using thin plate glass mirror blanks for grinding your telescope mirror:

* Thin mirror blanks are less expensive, allowing more people to afford the hobby of grinding their own telescope mirror.

* Choosing a thin mirror blank gets you more aperture for your dollar.

* Telescope mirrors made from thin mirror blanks take less time to thermally equalize with the surrounding air when moving your telescope out of your house or car, or from the ongoing falling temperatures experienced after nightfall while observing. This is important because faster temperature equalization means less time your telescope mirror spends "warped" from the rising and falling temperatures around your scope.

* Thin plate glass mirror blanks are lighter than standard mirror blanks, which allows you more flexibility in designing your telescope tube assembly and mount.

* When grinding a telescope mirror, you will find that plate glass takes less time to grind and polish than a mirror made from borosilicate glass.

Please see the Buy Telescope Mirror Blanks page for low prices on plate glass mirror blanks.

If you'd like to buy a complete mirror grinding KIT, with all abrasives and grinding tool included, please see the Buy Telescope Mirror Kits website for the lowest prices on plate glass telescope mirror grinding kits.