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Author Topic: Machine made glassware — Safety Rim: any input?  (Read 955 times)

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Offline David E

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Re: Machine made glassware — Safety Rim: any input?
« Reply #10 on: February 23, 2007, 02:29:06 PM »
Connie: the single tiny bump is present and as you describe: an artefact of manufacture. Thanks.

There is also a slight thickening of the rim, so I imagine this was deliberate.
David
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Offline Frank

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Re: Machine made glassware — Safety Rim: any input?
« Reply #11 on: February 23, 2007, 02:44:04 PM »
... question as to whether the Dema glasses had a deliberate safety rim...
Deliberate
Frank A.
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Offline Adam

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Re: Machine made glassware — Safety Rim: any input?
« Reply #12 on: February 23, 2007, 09:34:07 PM »
Many blown items (except those which are entirely hand-finished over the chair and bottles) have to be separated at some stage from the "moil", or whatever term is used locally for the bit which has either been attached to the blowing iron or where the blowing head of the machine has located.  The better-quality ones are cracked off and the rim ground, perhaps bevelled, and polished to give essentially a flat top.

With cheaper and/or mass produced items it is common for the article to be held upside down and the moil "burnt off".  The latter is a common term but of course glass won't burn - "melted off" would be more accurate.  A ring burner (gas/air or gas/oxy) is applied while the article is rotated until the moil drops off.  The resulting beaded edge is unavoidable and is an effect of surface tension.  It will of course add strength to the edge but that is sheer good luck and a bonus for the marketing people.  As the moil drops off, the last point of contact results in a slight string which immediately melts back to form the tit or pip.  This is always present and varies from very obvious to almost invisible.  Most people aim for the latter.

Adam D.


Offline David E

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Re: Machine made glassware — Safety Rim: any input?
« Reply #13 on: February 23, 2007, 10:20:40 PM »
Many thanks Adam! :D
David
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