The Purple-X lamp was a professional blacklight lamp designed for professional use. The filament is overdriven to last 50 hours, so you get high enough of a color temperature to produce an impressive blacklight effect almost as good as fluorescents. However you can only leave this bulb on for 5 minutes, they sure get hot! This bulb was made in '68, but were made into the 80s.
Glass and wood glass blocks UV starting from 300nm downward.
In order to cause the filament to produce UVA in a similar amout as fluorescent BLB, it is must be burned at a very high temperature.
Since most of the incandescent BLB lamps with an overdriven filament still produce far less UVA then BLB fluorescents, the theoretical temperature that the filament should be in order to compete with the BLB fluorescents (Especially when think goes to UVB) is above its melting point.
The maximum temperature that filament can withstand to make a useful incandescent lamp is 3400'K (5,660'F or 3,126'C) which is achived by Photolita photoflood lamps by Philips lighting Europe which have a mere 4 hours life. Even so the Photolita lamps don't emit as much UVA as BLB fluorescents.
Halogen lamps for projection which also have a filament with a temperature of 3400'K produce UVA and UVB (And even UVC), but not as much as fluorescent BLB and sun-taning lamps or gerdimical lamps.
I do know what it means for the blackbody radation curve for the filament that burns that corresponds with the color temperature.
Since the filament is burning hotter temperature which that shift the blackbody radiation curve toward higher frequency. Hence more radiation beyond violet part of the spectrum.
There was so much more variety in the lighting market back then. It is today almost impossible to find a blacklight incandescent in another wattage than 75W.
I couldn't agree more Vince. 30 years ago, and to a lesser extent 20 years ago, you could look in the lamp catalogs and find colored bulbs from 6w to 100w, silver bowl bulbs from 60w to 1000w, general service incandescent lamps from 15w to 1500w, street series incandescent lamps from 1000 lumens to 15,000 lumens, etc etc etc. Now, the only colored lamps left from the big three are transparent 25w party bulbs and/or imported, all silver bowl bulbs either discontinued or now imported, series incandescent lamps down to 2500, 4000 and 6000 lumen lamps and imported, and general service lamps mostly up to 500w (but GE still offers the 1000w).
Login
In order to cause the filament to produce UVA in a similar amout as fluorescent BLB, it is must be burned at a very high temperature.
Since most of the incandescent BLB lamps with an overdriven filament still produce far less UVA then BLB fluorescents, the theoretical temperature that the filament should be in order to compete with the BLB fluorescents (Especially when think goes to UVB) is above its melting point.
The maximum temperature that filament can withstand to make a useful incandescent lamp is 3400'K (5,660'F or 3,126'C) which is achived by Photolita photoflood lamps by Philips lighting Europe which have a mere 4 hours life. Even so the Photolita lamps don't emit as much UVA as BLB fluorescents.
Halogen lamps for projection which also have a filament with a temperature of 3400'K produce UVA and UVB (And even UVC), but not as much as fluorescent BLB and sun-taning lamps or gerdimical lamps.
Since the filament is burning hotter temperature which that shift the blackbody radiation curve toward higher frequency. Hence more radiation beyond violet part of the spectrum.
Thanks for reminding me, must look for it.