//////////////Aside from the obvious, (the paint doesn't glow well after 50 years and engraved clear plastic was "in" at the time) does anyone know of any reason for the change from the "black" light instruments ('47-'52) to white light ever after? TIA John ///////// ------------- I thot it was just ol' phosphorescent paint. Is there a difference between the old paint and the new stuff with which they restore those instrument faces? This is more interesting than I thot. I THOT it was probably just a stying change. I really kinda liked the "black" light tho. I think even Ford had it in '49-'50 but changed in '51. John ------------ No radiation danger from fluorescent paint as used on the Stude panels. The numerals glow because the paint is bathed in long wave UV from the purple glass coverd bulbs. Exactly the same principle as those black light poster in the '60s. Some military vehicles and aircraft had radium dials on the instruments that used a tiny admixture of radium salts in the paint to cause it glow. They would glow in the dark with no external light excitation at all. The radium dials probably don't pose a measurable hazard to the user of the vehicle, but some of the workers who applied the radium paint got cancer from the habit of using their lips to form a point on the paintbrush. I think the Stude panels go bad because the fluorescent agent in the paint oxidizes or degrades in some other fashion. But I don't think degradation of the panels was a concern back in 1952. Probably more a cost issue than anything else. Gord Richmond -------------------- Stewart Warner, maybe? They made the instruments in my Weasel, and I think at least some of them have actual radium dials. You don't need anything to excite radium; the light comes from the radioactive decay of the radium itself. Pure radium actually glows of its own right, but radium paint contains a tiny amount of radium (or other radioactive source) blended with a phosphor that emits light when hit by emissions from the radioactive source, typically alpha particles. The paint used on Studebaker instruments is more akin to the coating on the inside of fluorescent lamp tubes; it emits visible light when struck by UV light. The paint you talk about that weighs so much probably contains zinc sulfide; it is a pretty effective fluorescent material, and is also heavy. Zinc is also relatively non-toxic, and is certainly not radioactive. I kind of doubt the instrument factory would throw away actual radium paint, since radium is, and was then, hellaciously expensive. It's a daughter product in the decay series of uranium, and is never found in any great concentration, since its half-life is so short. To go off on a tangent, I used to have a Texas Instruments digital watch that used a tritium capsule to illuminate a fluorescent screen behind the display. Tritium emits beta particles (electrons) and they can be stopped by a sheet of paper, so no radiation ever escaped the watch. I actually moved the tritium capsule and screen to another watch when the T.I. watch cratered, but eventually it got too weak in light output to be of much use. Tritium has a half-life of only 3.2 years, IIRC. To recap: the reason they used to put radium in intruments was to obviate the necessity of providing other illumination; the radium was the energy source for the light from the dials. Remember the old radium-dial wristwatches? They had no lamps, and needed none. The "black-light" instrument panels used on Studes, needed the UV light from from the bulbs with the purple glass filters to excite the fluorescent pigment in the paint. Over the years, that fluorescent pigment degrades, or becomes contaminated, and no longer fluoresces as it did originally, even though the little UV lamps still work. I notice the degraded instruments look brown in daylight. If they did in fact contain radium, they'd still be glowing after all these years, since radium has a half-life of 4500 years. I believe the "black-light" panel was intended to provide the "look" of a radium dial without the expense of radium, not to mention the fact that by the late forties, people were coming to grips with the notion that radioactivity wasn't necessarily healthy. BTW, I just this minute went out and looked at the instrument panel of the Weasel, and sure enough, the numerals on the speedometer are glowing with a faint green light. Gord Richmond -------------------- They now make UV LED's, but they're not cheap. Check out http://ledmuseum.home.att.net/ledleft.htm for the info. I'm using a blue LED in my dash circuit. When I restored the instrument cluster, I removed the blue glass globes. These things are darker than a #20 welders goggle. The blue LED'S are not cheap either, $4.29 a pop at RadioShack part number 276-316. You can get them cheaper but they do not have the same intensity. I'm building a 12 volt drop down to 6 volt circuit to power my temp and gas gauge and putting a circuit on it to run 4 LED's to illuminate my dash. Parts alone run about $40. This circuit will support a 1 amp load at 6 volt and you MUST remove your blue glass globes to make it work. Contact me offline if your interested in one for yourself. David Carter ----------------- There is a building in White Plains NY that back in the 20's thru the 50's made the instrument faces for autos and aircraft. I think the name was Stewart something. They used radium as if it were finger paint and many of women workers wound up with a number of forms of CA from either inhaleing the fumes, or sticking the fine pinted brushes between their lips and using saliva to get a finer point on the brush. At the end of the shifts they would throw out the radium paint that was not used that day, and it would get mixed in with another material. On top of the embankment by the building still stands the New York Central (Metro-North). One of my next door neighbors tells of the story that his father would go over to the tracks in the winter by the building and witha shovel scoop up the coal that fell off the engines. The coaling tower was about 150 200 ft northof this building. Over the years they discovered that the driveway and the back lot of this plant would have a glow on moonless nights from the run off of the radium that was disposed of. As for the dial faces of Studebaker instruments, they used radium on the dial faces, infact their ads stated that the instruments were made just like the fighter planes and bombers that had just defeated our enemies. The purple light that is used in the guages is used to excite the radium. No matter how long the instruments are/were exposed to daylight, the light emitting properties wore off within 20 to 30 min of darkness. The purple lenses used infront of the bulbsgave off just the right amount in the proper spectrum to excite the radium. As for loosing the glow over 50 years or so. I have complete sets of NOS guages and speedometers, clocks, that have been sealed in boxes since they day they were made. The two NOS speedometers I have glow for about 10 min in a dark room, so do the clocks and the individual guages. What has caused them to loose there glow in the dark ability is 50 years of UV exposure. I have a few lbs of phosphorescent pigment that I mix with white vynl/glass ink. Once printed and exposed to daylight or artificial light the faces glow for about 5-7 min then go out. Using a plain white bulb i the socket area does give you back a fighter type guage, but if you place th e purple gel infornt of the white bulb, the glow is much mor brighter, and the black background does not show off. I am surprised att he amount of the material you need to add to the white ink to get to look th eproper color white, which had a green tint. I was the next time I did some dash guage faces, ad a retarder to the ink, then pour the pigment over the decal paper and letting the wet ink trap the pigment and re-claim the loose powder. The glow in the dark pigment is not cheap but not expensive, but a baby food jar of it weighs one pound. BG