[ATM] problem with mirror blank

[Richard]

Hi Jarvis,

Monday, April 9, 2007, 4:13:19 AM, you wrote:

JK> The old Pyrex blanks had lots of bubbles
JK> and it was not uncommon to grind through them with no harm to the
JK> finished mirror.

Yes, but it isn't Pyrex, it's a Soda Lime porthole. He could get down
to 5um and be ready to polish, or even worse in the middle of
figuring, and it pops and scratches the surface. As he is grinding a
soft substrate and it's only a 20 thou bubble, I'd be inclined to get
rid of it now.

-- 

Best regards,
  Richard in the UK