Last weekend Suzanne came home from an antique store in Fremont and plopped an old beat up suitcase in front of me. The suitcase contained a vintage ultra violet lamp on a hinged armature. The lamp was manufactured by Mastercraft Mfg. Industries in Chicago under the brand name Graham-Walker. Despite living in Seattle, we weren't really in the market for a UV lamp. However, a few months ago we had come across some reproduction early 1900's bulbs at Great Stuff down in Georgetown. The bulbs are clear glass and run at a lower wattage so the filament can be seen. The filaments come in a variety of patterns, with our favorite being the squirrel-cage design. We both agreed that this lamp would be perfect for one of those.
The UV bulb socket is slightly larger than the standard bulb size, so it would need to be replaced. The cord from the bulb to the switch box had cracked insulation that was entirely missing in some places, so I wasn't about to turn it on before rewiring it. The circuitry is pretty simple with just a switch and a large transformer to step up to the higher voltage needed to run the UV bulb.
I replaced the damaged wiring and finally got to test it out. The transformer had a nice loud hum and the UV bulb was too bright to look at after a few seconds. Since I couldn't really get to the transformer to check it out in depth, I shut the lamp off and got to work replacing the bulb socket and removing the transformer from the circuit.
Unfortunately, everywhere I could think of that would sell reproduction bulbs in Seattle seemed to be out of stock. I didn't want to pay for shipping since the bulbs are expensive enough to begin with. Finally, this weekend I managed to get my hands on the last FerroWatt squirrel-cage bulb in stock at Rejuvenation (which has a beautiful storefront south of downtown). We brought it home and plugged it in. It was a bit bright (they only had the 60W model), so we plugged the lamp into a dimmer switch to bring it down a bit. The result was exactly what we had in mind from the start.
I haven't been able to find much information online about the lamp. A search on the model number yielded a Danish collector with a somewhat disturbingly large collection of vintage IR and UV lamps, including an identical model. The original bulb is a 100W General Electric Mazda S-4, which according to a spec sheet at Lamptech, was (first?) manufactured in late 1940. The only similar style lamp I've come across is a Hanovia Alpine Travel Sun Lamp for sale on Amazon. The seller lists it as 1940s. The two have identical on/off switches, so the Graham-Walker is probably from the 1940s as well.
I have some more pictures up in a photo gallery.