1947-52 Blacklight Illuminated Gauges

[Lark Hunter]

One of the many spiffy features of Studebaker's first generation postwar cars, is blacklight illuminated instruments, and I believe they may have made mention of this being derived from WW2 aircraft in some of the sales brochures. From what I've read and observed, this is only partially true... most of the aircraft instruments either used radium paint, which allowed gauge faces and dials to glow continuously for a number of years, even in the absence of light; or small cold cathode fluorescent tubes in the cockpit to make UV sensitive paint glow (something like a blacklight poster). This setup stopped glowing immediately when light was extinguished. ...Studebaker used standard incandescent dash light bulbs shining through a dark purple filter to accomplish the latter effect. Ford also employed this method in 1949 and 1950, reverting to regular old direct illumination for '51.

The problem is that the paint degrades and no longer fluoresces after 70 years, and I'm guessing that it may have been pretty dead on a lot of cars by their 20th birthday. It's pretty common to hear gripes about unreadable instruments at night from owners of these cars, as well as shot-in-the-dark attempts to get useable dash lights again... from brighter bulbs and LED's, to pulling off the purple filters and tossing them in the garbage.

So, here's the questions: Has anyone experienced these instrument panels back when the numbers still glowed? What color did they light up? Was the radio dial also illuminated in the same fashion? Has anyone restored gauge faces back to this original configuration? I have played around with and used this type of lighting for a few projects, and think it has relevance beyond novelty applications... specifically remember an alarm clock that was blacklight illuminated; it lit up brightly and was very readable, and I didn't have to throw a towel over it to keep it from spraying stray light on the walls and ceiling.

[6hk71400]

I drove a 1948 LandCruiser from Northern California coast city to Tucson. I got a late start and soon it was night time. No instrument lights, so what I did was buy a $4.00 flashlight and would shine the light on the gauges. They would shine a soft green glow for a short period of time so I could check temp oil and speed.

Most folks tell me the filter for the light is key. I have never torn into the panel so I can't tell about that but I don't think that the paint is bad, JMHO. Also, there was a story around that the paint was made with small amounts of radon which was stopped when it was discovered the ladies at the factory used a paint brush that they moisten with the mouth and ended with cancer. Unsubstantiated; that story came from my High School chemistry teacher which LBJ was president.

Bob Miles

[52-fan]

The dash on my 52 Champion glowed a pale green. I remember very well shutting it off at night and the gages continuing to glow for several minutes. The radio was lighted by a regular light inside. The car was 19 years old when I got it and the gage lighting worked well for many more years.

[Dwight FitzSimons]

I assume that the material used in the paint was radium, a radioactive element. Watches used it until it was banned. Industry sometimes does the DUMBEST things. (Without looking it up I think that radon is a gas.)
-Dwight

[RadioRoy]

Was the radio dial also illuminated in the same fashion?

No. At least in 50-52, the original radio dial glass has the paint that glowed with black light, but the bulbs illuminating the dial do not have the black light filters. The bulbs merely have green filters, so they do not make the dial glow, even though the dial COULD have glowed if it had been given the correct spectrum of light.

The only thing I can figure is that there was no room for the thick purple filters over the bulbs. There is precious little room in these radios for even just the lights. The purple filters around the dash lights are quite thick.

I wonder if UV LEDs would fit and work?

[RadioRoy]

I assume that the material used in the paint was radium, a radioactive element. Watches used it until it was banned. Industry sometimes does the DUMBEST things. (Without looking it up I think that radon is a gas.)
-Dwight

Nope. It was not radium or anything radioactive. It merely glowed in response to UV light. Radium glows without any light source at all.

[StudeRich]

/Cut/So, here's the questions: Has anyone experienced these instrument panels back when the numbers still glowed? What color did they light up? /Cut/

All of the Painted on Markings and Needles Glowed a Bright Green, of course the "Light" was all a Purple Glow from the thick, Glass, Purple Lenses over the Bulbs. Very easily read and beautiful.
Dad had a '49 Lincoln Cosmopolitan that was the same, and a '50 Ford.

[rockne10]

My biggest memory of those gauges as kid was riding in the back seat at night and seeing the gauges reflection in dad's door window.

[MarkCrowel]

Nope. It was not radium or anything radioactive. It merely glowed in response to UV light. Radium glows without any light source at all.

That's a relief to know. Thank you for that info.

[Edsel Face]

A movie was recently released about this called Radium Girls. I believe it is on Netflix streaming. The girls in the factory were painting radium on clock faces and wetting the brush with their tongues. Several died from radium poisoning. They literally became radioactive.

[Lark Hunter]

Thanks everyone for the answers and information! It sounds like the numbers/markings were done in zinc sulfide paint, which tends to appear off white during the daytime, and usually glows a greenish color in the dark... depending on the doping agents used (usually copper). These phosphors are also excited by UVA from blacklight sources, as well as alpha particles emitted by radium... radium itself causes a weak blue glow; it was most always mixed with zinc sulfide paint to net that never-ending greenish light. I think the latter was more often used in places where an external light source might be impractical or not available, so it would be redundant on a car's instrument panel. Either way, zinc sulfide loses its efficacy over time, and takes more light or radiation to glow- and glows for a shorter period of time after light source is removed. I have a couple of clocks with radium dials that no longer illuminate on their own, but will if you shine a bright light on them or put them under fluorescent blacklight. The radium is still as hot as it ever was, as it has a half-life of 1600 years! And I also learned that radium *does* give off radon gas as it decays... so probably add adequate ventilation to the list when you've got radium dial stuff around.

[Lark Hunter]

All of the Painted on Markings and Needles Glowed a Bright Green, of course the "Light" was all a Purple Glow from the thick, Glass, Purple Lenses over the Bulbs. Very easily read and beautiful.
Dad had a '49 Lincoln Cosmopolitan that was the same, and a '50 Ford.

Ahh... never knew that FoMoCo used it in other lines besides the Ford. I've always liked the 1949-50 Lincolns more than most!

[Lark Hunter]

No. At least in 50-52, the original radio dial glass has the paint that glowed with black light, but the bulbs illuminating the dial do not have the black light filters. The bulbs merely have green filters, so they do not make the dial glow, even though the dial COULD have glowed if it had been given the correct spectrum of light.

The only thing I can figure is that there was no room for the thick purple filters over the bulbs. There is precious little room in these radios for even just the lights. The purple filters around the dash lights are quite thick.

I wonder if UV LEDs would fit and work?

Appreciate it, Roy! These are the little details I'm always digging for. Yes. Blacklight LED's would definitely work... probably too well. Was looking at examples of the old Sony clock radio model that I used to have, and many people have replaced the little fluorescent blacklight tube that's always burned out and no longer available, with LED's... it works very well. Compared to either of these sources, an incandescent bulb with a Wood's glass glass filter does produce UVA, but it's in minuscule quantities. I wish I had a car in the 47-52 range to play with; or even a few clusters, clocks, or radios... but that'll likely have to wait until disposable income is a thing again

[6hk71400]

Tory,

There are some 52 Commander's here in Tucson. I gave one away no cost but last I heard, the person wanted $2,000 for it. It was complete and had a decent interior. Engine was stuck but that could have been freed.

He also acquired a 51 Pontiac but I don't know what shape it was. He thought about asking $12K but I gently as I could told him that unless it is a convertible, that figure is way off market I also told him that my Overdrive equipped running 56 President Classic was purchased for $1,400 plus shipping of $700.

Had I known you were interested in the 52, I would have made you the same offer as I did on the 61 Lark. One night, I did shine the flashlight on the cluster and still got the green glow.

Bob Miles

[Champ51]

The 70 year old paint on our car's gauges glows brightly at night thanks to some UV LEDs installed in place of the regular bults. They continue to glow after the bulbs go out, although not as long as they did 50 years ago.