Quote:
Originally Posted by Satchmo
Sydney Glass at Padstow should be able to cut 25mm plate glass blanks for you.
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I would be hesitant
on ordering the 25mm plate glass as supplied by Sydney Glass.
Some time ago,(if you search through the thread "Are there any amateur mirror makers alive in Oz/NZ" you will see an account of the reply I received from Sydney Glass concerning the quality of their 25mm plate glass at that time, and I would doubt that the current quality would be any different, unless they have changed their supplier.) I had requested them for the supply of the 25mm plate.
A shortened version of that post:
I received the following reply: "We have got some 25mm clear float, but it is "SO BADLY ANNEALED" it is impossible to cut conventionally. We use water jet and often supply panels of this to telescope enthusiasts".
When I asked for supply of a full sheet cut in quarters, the reply continued: " there is no point in providing you with stock glass because of "THE CUTTING PROBLEM" ".
It is ESSENTIAL that a mirror blank has at least a reasonable anneal if it is to be the building block for a successful mirror. I believe many a budding amateur
mirror maker is discouraged by trying to fabricate a mirror out of a substandard substrate.