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[herptrader]

Originally Posted by Renagade

most 12 volt halgens have a 'uv block' be aware. this is because they are used in display lighting and the uv emmitted destroys the artifacts. if you can scource ones without i'd also be keen to get some.

The front glass can be easily removed as it is usually just glued in lightly. (You can prize it off with a bit of care.) That said it is not just their to block UV. Halogens contain halogen gas under pressure. If the glass in the bulb fails for any reason it shatters and without the glass front plate will shower hot glass fragments everywhere. I have a couple that have turned into "rattles" when they ave failed with the front glass in place. (Normal incandescents have a vacuum inside and tend to implode rather than explode if the glass fails.)

Another thing to consider is that halogens need to run hot to function properly. This is to do with the exchange of molecules between the filament and the gas which does not happen evenly if they are not run sufficiently hot. On old globes you often see a layer of dark on the inside. This is filament that has dissolved into the halogen gas and settled in the glass rather than being re absorbed by the filament. The glass cover is probably a factor in helping keep the bulb at the correct operating temperature.