Some information on CRT’s- Honest and Accurate Unlike Much of What You Read on the Topic Elsewhere.

While this subject is a little tangential to the concepts of the blogs, it does have a place here. The subject is Cathode Ray Tubes or “CRT” for short hand. Because of the proliferation of laws recently and potentially soon to come to pass: the potential parts sources in general of salvage materials to pull parts from or repair may dry up completely. In no small part due to the misunderstandings of what is actually in many electronics and just what component may be to blame, and without specificity as to what vintage of item is of concern as well. So as a result “blanket” laws are thrown at the issue.

There is a great hue and cry over CRT’s entering the waste stream and there are “those who mean well” who only have a small fraction of the real information about them and thenapply that little bit of knowledge over the full spectrum even to where it does not belong or does not accurately apply. As a result the concerns about lead within CRT’s leads to a great deal of misinformation. This post seeks to dispell some of that ignorance with a rational discussion on the subject. Which is important because of a number of large piles of abandoned CRT’s and CRT glass being abandoned and then treated as if it is comparable to “Love Canal”.

Now, most of the CRT’s that are in the waste stream today are post 1975 vintage. And that is significant because of how CRT’s were made prior to about that year were usually made differently than those after that year, and there is some overlap in technologies. When CRT’s came on the scene for televisions after WW2, most were black and white TV sets and most were made with a metal shell. The glass face of the picture tube and the glass neck that held the electron gun were essentially bedded in a lead seal between the metal shell and glass face and the glass neck. That method was continued when the glass envelope or in scrap terminology- the “Funnel Glass” replaced the metal shell. The glass was aluminized internally, and some insulating materials were applied externally to retain the same eletrical characteristics the metal shells had, but the black and white tubes (White Phospor coating inside actually) began to be made with the neck formed with the funnel essentially being just one piece of glass, but the face was still bedded in a lead seal between the face and the funnel for a while. It was not until later technologies of late 1960’s into the the 1970’s where the face glass was fused to the funnel for the White phosphor CRTs thus removing all of the easily recoverable lead from CRT production once steel pins were adopted as well.

In the 1950’s in the US and Canada, color TV sets began to appear, RCA’s CTC1 chassis being among the first US color sets. Now the color sets incorporated 3 different phosphor colors of red, green and blue. Each color also had it’s own electron gun and in order to make sure the color gun was hitting the same color dot of phosphor on the face, there was a metal (iron) screen mask between the guns and the phorphors on the face glass. Now the important thing here is these tubes were made to be rebuildable. So much so that you could get the equipment and supplies to rebuild the CRT’s that did not have burned phosphors in your own garage. These CRT’s were made with lead bedding between the face and funnel and the neck and funnel which held the gun assembly. The “Frit” as it was called, was where the gun assembly would bed into that funnel, be it a metal funnel or glass funnel.

As color TV set prices dropped, those tubes made roughly after 1973 no longer had a “frit” and were no longer garage rebuildable. My dad actually worked with a fellow who did rebuild the CRT’s in his garage, and I met him and talked with him about the process back in those days. With the introduction of the Sony “Trinitron”, which actually still had the 3 electron guns, but had an assembly that worked slightly different as a couple of tube elements that had been 3 seperate items each in RCA, GE and others CRT’s and remained so, were now handled by one element instead of three in the Sony products. These Trinitrons were not garage rebuildable. and their introduction also corresponded to the demise of many neighbornood TV shops as sets got cheaper and repair parts got more expensive and labor became a major factor of a repair cost. Color CRT’s were rebuildable even with fused glass parts or burned phosphor coatings, but it required the facilities of on par with a factory to do so- which remained possible into the early part of this century- and they were not cheap, but it was done.

The last phase of CRT development was the elimination of lead seals, which is roughly about 1975 as the main manufacturers cut costs where they could and eliminating the lead seals went a long way towards meeting that goal. By the time CRT computer monitors came on the scene, the face glass and neck were fused to the funnel glass- no lead, and with steel pins for the gun leads, no lead based solder was needed for a connector. Just a plastic aligner was glued on the end to protect the evacuation nib and hold pins in position and provide an index so the CRT’s could be connected correctly.

So where is the lead? Simple- Lead is used as a clarifying agent for glass. The “float glass” of your home’s windows, or the tempered and laminate glass in your motor vehicles have lead in the glass as a clarifying agent as well- this is why curbside recylcling never included old windows in their segregated glass collections. The key is, the amount of lead added can only be on the order of 7% to 8% by weight- total, otherwise the glass becomes weak. So in short- when you looked at the face of the CRT, you were looking at what is known as “Lead Crystal”- just like fine Lead crystal goblets you get from companies known for the product like Swarovski. You can landfill window glass, but not CRT’s. Not even parts of CRT’s because there is so little known of their construction or evolution of the technology among those making laws or writing law administratively or involved in regulation or anything pertaining to them. They regulate something that they themselves have little understanding of- which has created a log jam that really does not need to exist.

Can the lead be recovered from the face glass? Yes, but not easily, you need a foundary hot enough to melt glass and keep it molten long enough for the lead to settle out or evaporate. Now, there have been those who profit on that lack of knowledge as it protects their industry from competition, and there is other needless wastes of tax dollars that directly arise from this lack of knowledge as well.

I base my knowledge on having worked with CRT’s in computer monitors and TV sets as well as test equipment. Plus having dismantled a few CRT’s back before the times of the excessive eroneous regulation set in. Not to mention the literature that was prodcuced in the various “Tube Data” books. Though some of those did not update after about 1967 as tubes were being quickly displaced by transistors and the need for that tube manual disappeared. That; along with an understanding of physics, chemistry, and actually evaluating many pieces of government published documents that were largely in error because they did not vet the sources of their information correctly or adequately “because they meant well” with their agenda. But those failings that have led to misinformation are not going to be addressed here with specificity, because there is not enough space. In other political climates I would show step by step what is in a CRT, but to do so here would likely have them kicking in my door for daring to open one up.

What else is in a CRT? There are the phosphor coatings in all CRT’s which can potentially be an environmental issues- namely algae bloom and potential toxicity in concentrations that “might” accumulate in uncontrolled accumulating landfill runoff. And it is important to mention that there is no Mercury in CRT’s, as it is the phosphors that light up when struck by electrons- mercury would not allow a CRT to operate in the manner they did or do, so popping the evacuation nib is the safest way to remove the vacuum. There is also Thorium on the heater filament and outer heater sleeve which is needed for electron emissions at the heart of the function of the CRT. The gun is easily snapped off at the neck and routed accordingly to recover those materials, so removing that from the waste stream is very easy and recovering those materials is fairly easy to do. However the cost of recovery of those other remaining recoverable materials is great compared to the return on the materials recovered. The color CRT’s have that iron mask, and those few remaining old vintage CRT’s (of which there are few in number these days that still have easily recoverable lead), some few of those have an iron shell- but not many when viewed as a percentage of all the CRTs that have been manufactured or are still in use. Yet recycling trade publications like a recent issue of “Resource Recycling” are still of the belief that the way a CRT was made in 1955 is exactly the same way it was made in 1995- and nothing could be further from the truth.

Therein lies the problem.

So the key is knowing how to identify the old and new technologies, but this requires those involved in regulating the recovery of the CRT’s to actually know more than they do now, or to educate themselves- but it upsets their world view- so most will have none of it.

Not all CRT’s are created equal- but all are being treated as if they are; which makes things very expensive in a needless manner. And that circles back to people “who mean well”. Those CRT’s that have a frit- are either going to have a metal funnel, or a glass funnel AND a visible parting line regardless of glass or metal funnel- sometimes it is wide enough to catch a fingernail dragged across it. Most of those will have a soldered pin base as well, not bare steel pins. While those old ones do have steel wires coming from the gun or gun assembly, those are soldered to the pin base with a lead based solder- not much, but that is one location of a small additional amount of lead and you should know you throw out more lead in a used metal squeeze tube of cyanoacrylate glue than is used at this spot. Essentially- those CRT’s with a metal funnel and a soldered pin base, will usually have lead seals, and sometimes only a Frit. Many CRT’s for test equipment were not rebuildable and were made without lead seals. I have some vintage test equipment CRT’s that are proof of that.

Most CRT’s also have a steel band around the area where a lead seal “might” be- however when you remove the band- and most of those that had that metal band that is welded will not have a parting line and will therefore not have a lead seal because the glass of the face was fused to the glass funnel. In those CRT’s the lead is only found in concentration IN the glass of the face, and these are the majority of those CRT’s still out in circulation.

To be sure, if I am the owner of a recycling company that handles a great deal of CRT’s that I can charge good money to deal with them, I would have a vested interest in promoting the idea of the lead in CRT’s as being a real environmental issue if it meant I could keep a roof over my head and put bread on my table, and maybe pocket some for profit motivation. Especially to the point of suggesting all CRT’s were made in a manner where I could point to a bucket of recovered lead (never mind how old it is- and let a reporter or article writer just assume erroneously that all CRT’s are made as they were originally right after WW2.).

The true reality is the “risk” of the glass portion of the CRT’s is really no more significant than the window glass that is allowed in the landfill (providing the neck of the CRT is removed). Now, if an alternative use of that glass and window glass can be found, such as building materials, fiberglass insulation, siding materials, concrete admixtures, etc- I am all for it. But it is largely the glass industry that should reach out and seek out the potential alternative uses for the CRT’s glass just in good faith and Public Relations because no one else is doing it. Plus right now glass is also among the least profitable of the curbside collected recyclables. Never mind that glass is highly recyclable and very sanitary. It’s main drawback is weight, plus it breaks. But personally- if I have a choice between a beverage packaged in glass bottle versus that same beverage packaged in a “PET” bottle- Glass wins because there are no hormone disrupters that could potentially leach out of the other product.

And as a side note- it was recently announced a new plastic resin is in the works that will have Furans potentially leaching into the contained products- likely to appear on store shelves about 2017. “PEF”- Polyethylene Furorate. But that drags this too far off topic, so no further mention of it in this post, other than you can research “Furans” and find quite a lot of information.

Otherwise it could take decades (unfortunately) for this CRT matter to become ancient history, and likely not be fully resolved even then. And this is largely possible when one considers the push that has led to regulations concerning manufacturers being held responsible for their products at a product’s “end of life”. (Extended Manufacturer’s Resoponsibility). I can readilly see how this could easily open the flood gates for all manner of litigations between industries that provided the raw materials or individual components of a device arising from one poorly phrased state or Federal (national) law (and few of these are ever well written or concise because many of all laws are made by lawyers intended for courts to sort out details later.). And as far as landfill runoff is concerned- there are far more toxicities of other sorts to be found than one might realize and some are in greater concentrations than what you would likely find from landfilled CRT glass.

But if nothing else- this is my knowledged “two cents” on the matter.

The associated blog for above youtube channel
The main blog.
the begining point place to start
The tangential blog.
The passive solar blog- outgrowth from some projects of mine.

This entry was posted in Cathode Ray Tube, CRT, Frit, Homebrew, Project, Recycling, Uncategorized and tagged , , , , , , , , , , . Bookmark the permalink.