Vacuum Coatings Scientific Mirrors

For orders please telephone us on 020 8 520 5353

  Telescope Making Supplies
  Astronomical Telescope Mirrors and Flats

Due to pressure of work, we are not able to offer a comprehensive list of mirrors and flats for sale. However, if you have a specific requirement please ask us as we still have the occasional mirror and flats ( below about 2 1/4inch m/axis) available.

We do have a limited number of original Pyrex blanks made in the 1980's. These are as used by David Hinds ( and sold by B. C. and Fuller, Jim Hysom ( A E Ltd.) Orion Optics and H. Wildey to name a few manufacturers. Because of the way they were poured, they retain original, concentric stress patterns which show if tested using polarised light. Of the thousands of mirrors made using these, there are no known cases of optical problems caused during mirror manufacture. Jim Hysom always maintained it was best not to grind the backs of these blanks. In that way, once ground and polished both surfaces retain their original surface tension.Mirrors recently tested that were ground and polished over 30 years ago, still retain perfect figures confirming the safety of using these blanks.



  Original Moulded Pyrex (Low Expansion) Mirror Blanks
  Size Price P & P
  4 " Dia. (103 mm) x 3/4" (20 mm) thickness £15.00 £6.00
  4 1/2" Dia. (115 mm) x 1/2" (12 mm) thickness £15.00 £6.00
  6" or 6 1/4" Dia. (152-159mm) x 1" (25mm) thickness £20.00 £8.50
  8 1/2" or 8 5/8" Dia. (216-219mm ) x 1 3/8" to 1 5 /8" (29-35mm) thickness £40.00 £16.50
  11.9" Diameter x 1 1/2" Thickness ( None available at present ) £75.00 £22.00
  11.9" Diameter x 1 1/2" Thickness with 2" Centre Bore £70.00 £22.00
  Suprax (Low Expansion)
  Size Price P & P
  7 3/4" (200mm) Diameter x 1" (25mm) One only available £42 .00 £16.50
  9 7/8" (250mm) Diameter x 1" (25mm)Temporarily out of stock £50 .00 £16.50

  Grinding Powders

Silicon Carbide (C)
Rough grinding powders for grinding mirrors to the required curve starting with flat (non diamond generated) mirror blank and grinding tool.

Three grades of coarse grinding powders are listed below. The table advises the probable amount of each grade of powder needed to grind the mirror sizes listed. The powders are priced at a cost per per pound (nominal 1/2 kg) in weight. Any amount, greater or smaller than this may be purchased.

  Mirror Size 6" 8" 10" 12" Price per lb
  Grade 60C     1 lb 1 lb £6.00
  Grade 80C 1 lb 1 1/2 lbs 1 1/2lb 2 lbs £7.80
  Grade 120C 1/2 lb 1/2 lb 1/2 lb 1/2 lb £7.80

Two grades of smoothing powders are listed below, for removing all pits produced during rough grinding and scour marks if grinding pre-generated blanks. The table again advises probable amounts needed to grind each mirror size. Again any quantity may be purchased. This information is again repeated below for the other mirror making materials.

  Mirror Size 6" 8" 10" 12" Price per lb
  Grade 220C 1/4 lb 1/4 lb 1/2 lb 1/2 lb £7.80
  Grade 320C 1/4 lb 1/4 lb 1/4 lb 1/4 lb £7.80

Emery Powders (E)
Fine grinding powders to prepare the mirror for polishing.

  Mirror Size 6" 8" 10" 12" Price per lb
  125E (equiv. 600C) 1/16 lb( 1 oz) 1/8 lb 1/8 lb 1/4 lb £18.00
  50E (equiv. 1000C) 1/16 lb ( 1 oz ) 1/8 lb 1/8 lb 1/4 lb £20.00

  Polishing Powders

Cerium Oxide
Two very fine grade powders are available; use sparingly for fast, fine polishing and finishing.

Auerpol 1 to 4 micron powder is really ideal for most polishing needs. Used in suspension, it gives a fast polishing 4 micron grade if taken soon after stiring. Left to settle out it leaves the finer 1 to 2 micron powder for fine polishing and figuring.

The Auerpol W100 is 1 to 1.4 micron grade. This would normally be needed only for the final fine figuring of an optical surface. It is sold in small 1 oz (1/14 lb) packets at a cost of £2.00.


  Mirror Size 6" 8" 10" 12" Price per lb
  Auerpol 1 to 4 micron 1/10 lb 1/10 lb ( 1 oz ) 1/8 lb 1/8 lb £20.00
  Auerpol W100

1/11 oz oz8


1 oz 1 oz 1oz £28.00

Coal Pitch Tar (Sorry no stock)
Satisfactory hardness for polishing low expansion materials, a touch of turpentine will aid in moulding the lap. Add a little more turpentine as needed to polish plate glass.

  6" 8" 10" 12" Price per lb
  1 lb 1 1/2 lb 2 lbs 2 1/2 lbs £4.00

Post and packing charges for orders up to:

  1lb (460gms) 2lbs (920gms) 3lbs (1400gms) 4lbs (1850gms) 6lbs (2750gms)
  £4.50 £6.50 £8.50 £9.50 £15.50

For orders please telephone us on 020 8 520 5353

(We are not always able to immediately answer. If you connect with our answerphone, please leave a message stating, if possible, what you need and where possible size(s) if applicable. Also make sure you leave a contact telephone number for reply. Mobile phone reception can be variable, so please be as clear as possible when using mobile phones)

If you are near to, or live in N W London, you might like to know about the Hampsterad Scientific Society and the Hampstead Observatory. There are weekly (weather permitting) free public observing nights and an associated ( CATS) telescope making group.

Here is a link to the 'Sky at Night' magazine's Telscope Making Video by two members of CATS. Camden Astronomy and Telescope Making Society which is affiliated to the Hampstead Scientidfic Society and has fortnightly Wednesday meetings in Highgate