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Re: [ATM] convex secondary
And pretty high temp saucepans?
i don't know of any metal that melts at a higher temp that glass?
Joe
Ken Hunter wrote:
>Never saw saucepans that had rims that would mate up
>to those on the Pyrex disks... We're talking of even
>OLDER Corning disks that had an annular ring around
>the backside. They looked like they were done in molds
>from Pyrex glass that was "pulled" from a dollop while
>in a "taffee like state" , plopped into the mold and
>heated just enough to get the topside of the glass
>level with the mold top. The top side had rolled
>(tensioned) edges, the bottom had the rim. The sides
>were tapered.
>
>Ken Hunter
>
>
>--- "Steven L. Dodds" <steve@pcmw.net> wrote:
>
>
>>----- Original Message -----
>>From: "Joe" <nss@mwt.net>
>>To: "Ken Hunter" <atm_ken_hunter@yahoo.com>;
>><atm@atmlist.net>
>>Sent: Saturday, March 12, 2005 9:05 PM
>>Subject: Re: [ATM] convex secondary
>>
>>
>>
>>
>>>I loved those old corning blanks,, I always
>>>
>>>
>>wondered though what they
>>
>>
>>>used as a mold?
>>>
>>>Could handle the temps required and not melt, and
>>>
>>>
>>also have a polished
>>
>>
>>>surface.
>>>
>>>Joe
>>>
>>>
>>The old Corning blanks with the shiny sides and the
>>ridge on the bottom were
>>molded in saucepan molds. Pyrex Sauce pans were made
>>by dropping a glob of
>>molten Pyrex in the mold then pressing it with the
>>top mold. Telescope
>>blanks were made by dropping a double glob of Pyrex
>>in the bottom mold and
>>letting it sit until cool. The molten Pyrex without
>>pressing would fold
>>over on itself creating creases and voids, hence the
>>poor quality. It is
>>also the reason for the standard blank sizes. 4.25"
>>6" 8" 10" 12.5".. It
>>was the size of saucepans that Corning sold.
>>
>>There is your piece of trivia for the day.
>>
>>Steve
>>
>>
>>
>>Steven L. Dodds
>>Nova Optical Systems
>>http://www.nova-optical.com
>>
>>
>>>Ken Hunter wrote:
>>>
>>>
>>>
>>>>In the old days, Pyrex blanks were moulded in
>>>>
>>>>
>>forms
>>
>>
>>>>and were very full of in-homogenities and
>>>>
>>>>
>>striations
>>
>>
>>>>(SP)? These could be easily seen on most any blank
>>>>
>>>>
>>>>from several y. Lately, I've not seen visible (by
>>>
>>>
>>eye)
>>
>>
>>>>defects in the Pyrex disks that are currently
>>>>available. I would think that testing through the
>>>>
>>>>
>>back
>>
>>
>>>>would be possible with today's glass.
>>>>
>>>>Ken Hunter
>>>>
>>>>
>>>>--- Greg Jones <gregj888@comcast.net> wrote:
>>>>
>>>>
>>>>
>>>>>"Pyrex is not homogenous and has a lot of fine
>>>>>grain boundaries.."
>>>>>
>>>>>I've read this in all the old texts too but am
>>>>>wondering if it's true (or still true). Has
>>>>>
>>>>>
>>anyone
>>
>>
>>>>>checked a Pyrex blank in the last 10 yrs? Seems
>>>>>like to be low expansion it would need to be
>>>>>homogeneous, and how do you make it so it is not?
>>>>>
>>>>>
>>Has to be annealed too.
>>
>>
>>>>>I'm not saying it's any
>>>>>better now than 40 yrs ago, just suspicious.
>>>>>
>>>>>It's on my "to do list" to check, but still a
>>>>>
>>>>>
>>ways
>>
>>
>>>>>from the top.
>>>>
>>>>
>>>>>Greg Jones
>>>>>http://home.comcast.net/~dac20/dac_001.htm
>>>>>
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