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Phillips 100 watt Mercury Cap cement

Phillips 100 watt Mercury Cap cement

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What's up with the white and green strips?


Light Information

Light Information

Manufacturer: Phillips
Lamp Type:Mercury vapor
Filament/Radiator Type:Arc-tube
Shape/Finish:ED-23 1/2 Clear
Ballast Type:H-38
Socket Type:Mogul
Location:my collection
Factory Location:Bath New York
Fabrication Date:Sept '95
Application/Use:streetlighting.+ general lighting

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File information

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Album name:wide-lite 1000 / mercury vapor lamps
File Size:476 KB
Date added:Apr 26, 2019
Dimensions:2464 x 1848 pixels
Displayed:43 times
Date Time:2019:04:14 10:11:41
DateTime Original:2019:04:14 10:11:41
Exposure Bias:0 EV
Exposure Time:1/30 sec
FNumber:f 3.7
Flash:No Flash
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Focal length:4.5 mm
Model:COOLPIX A300
Software:COOLPIX A300V1.2
White Balance:0
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Apr 28, 2019 at 02:10 AM Author: James
In the early days there were many HID lamps where the caps became loose due to the high operating temperature. The reasons was that there was no cement type that had both good adhesion to glass and to metal. Since basing cement is extruded onto the inner wall of the cap shell, in the 1980s one of the Sylvania engineers was inspired by the then popular multicolour striped toothpastes, and patented the concept of a composite capping cement. If i remember rightly the white cement is silica-rich and forms a good bond to the glass, while the green is shellac-rich and forms a superior bond to the metal. Of course during life half of the cement will lose its adhesion on one side, but it can no longer crumble and break away due to the adjacent stripe that mechanically fixes it in place. The result is a considerable improvement in cap torsion strength at end of life.

Soon after this development a further improvement in single-component high temperature capping cements was made by Glassbond of the UK. It has since become standard to use that (or the lampmakers’ own-made slight variants), and the striped lamps were not made for very long.
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Apr 28, 2019 at 12:19 PM Author: wide-lite 1000
Thanks James, you are a welcomed wealth of technical knowledge pertaining to lamp making ! And your right, it DOES resemble striped toothpaste! lol.

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Apr 28, 2019 at 12:38 PM Author: Silverliner
Wasn’t it the Westinghouse engineers James? The Sylvania HID lamps never had basing cement except the medium based lamps. All the mogul base ones had mechanically attached bases.

May all the great lighting technologies have their place in history.

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Apr 28, 2019 at 02:34 PM Author: James
No problem, its good to spread the knowledge and document these things before people forget!

Dave, I had the info from a fellow Sylvania engineer who said it had been developed at Boston Street plant (or now I wonder if it was not at Loring Avenue, there were two lamp plants in Salem and the latter did mainly the high wattage types). It probably came first from incandescent lamps, since those run hotter.

But until finding the patent (if any) it would be difficult to confirm this, so if you have evidence that Westinghouse was first I could also believe that. Of course the big lampmakers all shared their patents freely between each other, and often one company had the idea and patented it but another would be first to develop the necessary machines and implement in production. This can make it really diificult to find out who invented what!

I wonder if there might be something on this in the Westinghouse Lamps R&D book by Kane & Sell - I will have a look in the library at work tomorrow, and ask again my old colleague in the labs what he remembers from his days at Boston Street.
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