Also from Wikipedia on CRT's
The glass envelope
The outer glass allows the light generated by the phosphor out of the
monitor, but (for color tubes) it must block dangerous X-rays generated by
high energy electron beam impacting the inside of the CRT face. For this
reason, the glass is leaded (sometimes called "lead crystal"). Color tubes
require significantly higher anode voltages (as high as 32,000 volts for
large tubes) than monochrome tubes, partly to compensate for the blockage of
some electrons by the aperture mask or grille, and the amount of X-rays
produced increases with voltage. Because of leaded glass, other shielding,
and protective circuits designed to prevent the anode voltage from rising
too high in case of malfuction, the X-ray emission of modern CRTs is well
within safety limits.
Again I ask - how many eons does it take for the lead to leach from the
glass?
Bill Eade
----- Original Message -----
From: "William Eade" <[EMAIL PROTECTED]>
To: "Main Discussion List for KPLUG" <[email protected]>
Sent: Tuesday, September 19, 2006 7:46 PM
Subject: Re: Don't just toss that TV
The coating on a CRT tube is not lead, it is a graphite based coating
called Aquadag.
Aquadag
From Wikipedia, the free encyclopedia
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Aquadag is a trade name for a graphite based coating commonly found in
Cathode ray tubes.
The coating can be on the inside of the tube, where it helps to maintain a
constant electrical field near the screen. Tubes intended for television
use often will have an aluminum flashing which replaces the internal
Aquadag, and also acts as a reflector on the back of the screen.
Aquadag is also painted in a band on the outside of many tubes. The glass
of the tube between the internal coating and the outer Aquadag can then be
used as a capacitor to filter the high voltage supply. Normally there is a
spring contact that touches the Aquadag. When this contact is missing or
loose, arcing will at times be observed.
When removing a CRT from a TV set, it is wise to discharge this built in
capacitor to avoid a shock hazard when handling the tube.
Bill Eade
----- Original Message -----
From: "Barry Gershenfeld" <[EMAIL PROTECTED]>
To: "Main Discussion List for KPLUG" <[email protected]>
Sent: Monday, September 18, 2006 11:49 PM
Subject: Re: Don't just toss that TV
As to the other 9%...I guess we're an urban curiosity. Well, it was the
CRT's. They are not lead impregnated, they are coated with lead (on the
back). This forms the high voltage anode and maybe does some shielding.
Anyway, I'm happy to comply as long as they're not taking my money at the
same time. Besides, I didn't have any way to dispose of them except to
break them up first. And I didn't want to do any experiments on how to
let the vacuum out of those things. I understand you threw bricks at them
when you were kids, and I understand that you can break the seal at the
back, but I'll let someone else do it, thanks.
So a little after noon I pull into the stadium and we are herded into a
Disney line that snakes up and back, down and around, then back and forth
three times. Picture 300 cars and trucks sitting there, engines idling
for an hour, we're all waitin' to save the world from pollution. And the
piles of stuff! Rich Ernst's garage and mine combined couldn't match
this. And I saw a lot of stuff there that I hadn't even gotten around to
buying yet.
Just imagine if the other 90% of you added your stuff to the pile.
Barry (but you'll never get my 60/40 solder!)
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