Phosphors/ coatings in TV tubes: toxic?

[myID]

Hi-

I obtained some high vacuum parts that were used in TV Tube production. (Nobody needs them any more because TV tubes also go the "Way of the Dodo").
There is à lot of white/ brownish powder in them (some Parts are obviously dust separators to protect the used Turbo Pumps).
What can it be? Will it be (super) toxic? Sure I always treat used vacuum Parts with care not knowing if they are contaminated but still would be nice to know what I am dealing with!

Kind regards
Roman

[DaveC]

Roman -

Since you don't really know the details of the history, it would be safest to treat the dust with some care. Perhaps consider a rinse with distilled water, before handling.

You've got cathode materials which are Ba, Ca, Sr, compounds, Getter residues similar stuff, and the phosphors themselves which are mostly oxides, sulfides and such...

But there could be residues from glass cleaning treatments which often used HF, or other nasty acids as well as metallizing, and so on.....

Probably want to avoid breathing any of the dust.

Dave Cooper

[Doug Coulter]

I'll second that. Many modern phosphors aren't real good for you to ingest. Nearly all of them are not water soluble though, so often you can just wipe them up with a damp cloth and ditch the cloth. Of course what I really used was a nice paper towel (Bounty) which is one of the better things for this kind of work.

I have done this to get the nice thick leaded glass recovered from old CRTs to use over my viewports and cut the X rays way down. I didn't get sick, is all I can say, but I was careful, too. After doing that I used glass polishing agent, cerium oxide, to polish the rough phosphor side and get an optically decent window. Worked out fairly nice and now I can use the mark one eyeballs to observe without X raying myself during a run. They have a lot of advantages over a web cam...

[richnormand]

This looks interesting Doug. Have you measured the actual attenuation of the glass at fusor voltages and flux. This could be different from the CRT usage and beam current/voltage?

[Chris Bradley]

In this scenario, white powders could be ammonium fluorosilicate, which can make its appearance in various vapour phase decomposition/deposition processes. If so, it will be soluble in water and produce an alkali (caustic) solution.

On the whole, whatever it is from this type of process, you should presume you need to be very careful indeed.

[lutzhoffman]

Hello:

Most modern ones are not that bad, mostly rare earth compounds. Red for example is a Europium compound in most modern picture tubes. I would still be careful, if lead can wind up in Kids toys from China, imagine what could wind up inside of electronics when some doh head figures out a way to save 2 cents, with something toxic.

[Richard Hester]

Beryllium phosphors (really, really bad news) have long been history. However, it is not a good idea to let any unknown finely divided powder get in your lungs. Silicates, though not at all in the same nastiness category as the beryllium-based phosphors, are still no joke..

[Richard Hull]

We used to smash fluorescent tubes up as kids. ... As many as 50 at a time and carefully reclaim the little mercury beads to make a large blob for fun stuff. I must have breathed in a lot o' that Calcium Tungstate powder that was commonly used for the phosphors. Still around, of course, at 64.

We used to saw up transite (asbestos hard board) for making asbestos clay wads in water to fashion rocket nozzles out of back in the late fifties. we would them fine machine them from there.

I breathed in a lot of evaporating Carbon Tetrachloride as watermark fluid during my youthful stamp collecting days.

My mom would have the carpet cleaners over on occasion and the sweet fruity smell of pure bezene as a small boy still lingers in my brain's odor catalog.

Dodged a lot of bullets that would send modern nervous nellie moms into hysterics and provide incomes to a lot of the current spate of lawyers.

Oh well.....

Richard Hull

[Doug Coulter]

Yes, I've measured the X ray attenuation. It's good but not perfect. The main downside is that the stuff is kind of dark so you lose some light too, and having to polish it is a job. I couldn't get it to cut clean, but you get a lot of tries to get a 6" piece from a 25" screen, and one was close enough to let me use silicone to glue it into a holder than hangs over the door/window.

If we go by glass -- one piece 3/8" pyrex pretty much lets it all through -- geiger pegged on x100.
Two pieces bring that down to about half scale. CRT glass about 1/2" thick (or a little thicker) gets you to half scale on the next more sensitive range, x10. Background here is about 1/10 that, or half scale on the x1 range (it's a real sensitive geiger counter) -- that's all cosmics here in the mountains, and far less than I've measured at some people's labs in this group.

As half scale on X 10 was probably going to get me in trouble with OSHA or some lawyer (I have employees from time to time) and I didn't like the darkness, Bill found a piece of really super thick lead glass from a hospital recycling outfit that really stops them all on my geiger, though his scintillator still sees some low energy dregs getting through -- but that thing also goes nuts on the radiation leaking out of a half inch thick lead pig with a little U inside. The hospital stuff is clear, so it makes taking good pictures a lot easier and of course, direct observations are better with it.

When you get to really decent fusion rates, though, all bets seem to be off. There is a third possible DD reaction that happens about 1::10,000 of all of them that makes 13 mev gammas, more or less.
Those come on through just about anything -- including the 1/4" thick lead I've coated my entire tank with (speaking of hard work -- that one one complex manikin to sew a dress for). In fact, with a thin lead high pass filter, it's as good as having a neutron detector to monitor fusion rates. Luckily it's only a ten thousandth of the total fusion rate so until you start doing much better than anyone here has, it's not going to kill you most likely. In my setup, running full steam at really good rates, I see about 4x the normal background on a pancake 10 feet away from those.

In our case, the count goes from the normal 48/minute to about 200 or so, up to maybe 250 if things are going really well.

[Doug Coulter]

Yeah, been there and done that myself, along with some other bad life habits -- smoking etc, and the entire sex/drugs/rock and roll business I did for awhile. I think some of us are genetically more lucky than others on those scores, or it just hasn't caught up with us yet.

Still, to me it's the life in your hours, not the length of your life -- it's how much you really live in a lifetime that counts. If being "safe" means you don't have a life -- I'll choose not to be so safe myself, and that's landed me in the hospital a number of times so far, but nothing I'd whine about -- things happen. I do a lot of dangerous things -- carefully, it's not the danger I find attractive, but some of the things I do for fun *are* dangerous. So, the right approach IMO is to help the odds along to the extent possible by planning and training ahead insofar as possible, to help load the dice in my favor.
Gambling with dice I can load myself is the only kind I like to do....


So, in this example, I don't deliberately eat stuff that has rare poisons/dopants in it, I'm careful with it, because there's no special thrill in not being careful and it's not hard to avoid getting that kind of stuff into you.

Personally, I hate all lawyers except mine, of course...it's completely out of control out there.

I find the nannie state insulting myself -- who are they to say what I can or should do -- I see no evidence that even one politician is smarter or more knowledgeable than I. And they don't have to walk in my shoes in any sense of the words. So I prefer it when they stay out of my business.

An old Jimi Hendrix anthem comes to mind on this -- "If 6 was 9" to jog anyone who's heard it.

[Richard Hester]

Well, yeah - some folks are lucky and some ain't. I worked with a lot of nasties in my younger days (thinking back, I wonder how I escaped with all my parts more or less intact) and now find I need to limit my exposure to dust. A 95% mask is cheap insurance.