Beautiful video! It is interesting how the ballasts for Cooper Hewitt and the Type RF lamps are so similar. The bulbs, too. Although the ballasts are more similar than the bulbs
@@georgewills-ek1gg The only real difference is the fact that uncoated florescent tubes glow green instead of blue, just like germacidal CFL's. Which is why being in the same room with them running can be dangerous because of ozone levels increasing, where as this lamp doesn't do that and is thus perfectly safe.
I’ve seen other models of these that aren’t used for regular illumination. They were used for exposing blueprints and drafting plans to duplicate them. “Blueprints” are cyanotypes that copy the original drawings. The originals are made on thin velum-style paper that is semi-transparent. A sheet of paper treated with cyanotype emulsion is placed underneath the drawings and the “sandwich” is exposed to daylight, or preferably UV light (which is faster and stronger). After the allotted time the print is washed and what’s left is a light stable cyanotype “blueprint” negative copy of the original drawing (the lines are white and the background is blue). This lamp would allow drawings to be duplicated right on the drafting table. UV lamps can also be used in photolithography to etch lithographic plates. The plates are often exposed to a carbon arc through high contrast negative film transparencies. This lamp could be used but would take longer than than carbon arc because the photosensitive etching chemicals are quite slow to respond so require a very intense UV light. Where the UV light strikes, the plate is etched and becomes receptive to oil-based printing ink and where is doesn’t, the plate will resist ink.
@@alandaiello7268 this fixture emits minimal UV light due to the tubes glass composition. It was used for regular detail illumination in the 1920s & I have pictures showing them in use on assembly lines.
@@Mirroxaphene I have seen others of these used in drafting companies to reproduce blueprints as well. They must use a different tube for that? No matter what it’s a very cool lamp and you’ve done a great job restoring it and getting it operational. 😊 PS: I edited my comment above to correct it.
I have researched RF lamps and fixtures and the fixtures themselves were only made from late 1939 until 1942 because of the amount of copper the ballasts used and the increased rationing of precious materials during WWII and never made again however the replacement lamp, F85T10 lamp was available until the mid 1960s. This 450 watt mercury vapor "desk" lamp most certainly has more in common with the rectified fluorescent than a standard mercury vapor lamp which would likely date it no later than the early 40s. The only tubular mercury vapor lamp I've heard of is the H3000 A9 3000 watt industrial high bay, 132,000 lumens, in my 1954 GE lamp catalog.
Welcome back, I'm so pleased you're posting again. Wow! What a lovely, rare lamp! Thanks for a well documented video and demonstration of the lamp in operation.
The finest example of the technology in operation on video anywhere. Jeff Behary has the only other (2) videos but they are a mere few seconds long with no commentary. To be sure, this lamp IS emitting vast quantities of ultraviolet light, but all of it is absorbed by the glass envelope except for the 365nm "I" line, which is relatively harmless. The smell test is adequate here because the lamp envelope for a device of this age is either going to be fused quartz, which will admit all wavelengths of UV down to the "vacuum UV", or it isn't and is made of glass which is sufficiently protective. The "ozone free" lamps which add a small measure of titanium oxide to the fused quartz to block the 185nm line that produces ozone while continuing to admit the 254nm line, are a relatively recent invention and definitely did not exist in this lamp's era. Subscribed.
Impressive. I have a self-ballasted mercury lamp (on the other hand) rated for 220v input. I then had to buy a step-up transformer and it works just fine and very bright indeed. I researched that an "under-current" may damage a higher voltage bulb, so I didn't take any chances and got the step-up to 220v forthwith. But maybe, in your case, it's an obsolete odd number of voltage requirement no longer available?
To test if the light is giving out any UVC light, you can get cards with a phosphor that glows under UVC light but not under UVA or UVB. They also have a photochromic pigment that darkens when exposed to UV.
