this time with water. a 21FJP22. I picked up a small kidde pool (baby really) at target for 5$ fits just right. I don't have my camera handy but will snap a pic later. I used a exacto to cut the tape seam righ at the lens, then peeled it off. the pva as not as hard as I have on some other sets, more like cheddar cheese, maybe ti will go a bit faster than the last one I did (a RCA rectangle, the PVA was much harder on that one. I did that one with the low temp low pressure method. Hopefully the somewhat softer pva will let the water soak in and do its thing in not too many days.

I have the water just above the glue line. I can see that I will have to keep an eye on it for evaporation losses. there is also a bath cloth under the lens, I dont think its needed since the plastic liner bottom shoule be enough to protect it from scratching. I have it on a concrete covered porch.

here it is

give it awhile and it will pull right off.i think this is a much safer way than the heat method.good luck

yea after that report of the failure, I decided to hold off until a better method was tried. I like this one the most.

I was going to to the low heat (out in the sun and low pressure from chop sticks) like I did on the last one, but honestly I was concerned about some dopey kid chucking a rock from the back yard (it happens) an then I would end up in jail... so this seems the best and def the safest for the tube.

it took mine 2 months to fall off, i would try and get it a spot in the garage. There is no way I would let it sit outside that long.

The clear silicone worked out very well. The thing is super strong and sealed for life.

being a man of "science" I plan to add some yeast to it later. hmmm I wonder if a CRT weighs the same as a witch...

Update:

been about 10 days, I lifted it up and applied some pressure (finger nail under the lens) I could see some sign of release at the very edge, the pva was coming loose from the CRT face. Just a tiny bit mind you, but progress none the less....

I'm anxiously watching your progress. I've got two round color crt's that are in need of safety glass removal and I decided a long time ago I was not going to risk the destruction of the tubes (or myself) by using localized heat to pry off the mask. I've got my kiddie pool all ready to go and am waiting for the weather to finally warm up a little bit here in the North East.
Bob

If the PVA is indeed polyvinyl alcohol "PVA", then water solubility is really the only way to go. It essentially turns gummy after a while. If you can get some water circulation going it would certainly speed up the process. (a small aquarium pump directed at the PVA might help).

I used the same method on an oddball 15' rectangular(thick neck) crt from a conrac monitor,took awhile,but it worked.
Pat

agitation, I will see what I can do on that, will look for a small cheap pump.

I was also thinking of some tooth picks stratigically placed around the edges too apply a tiny bit of pressure, and open up the pva to more water.

The water does not dissolve the PVA in any way. It just somehow causes it to unstick to the glass.
The PVA sheet from the one I removed was in good shape. It didnt dissolve at all.

If the PVA is indeed polyvinyl alcohol "PVA", then water solubility is really the only way to go. It essentially turns gummy after a while. If you can get some water circulation going it would certainly speed up the process. (a small aquarium pump directed at the PVA might help).

It's actually of the family of Polyvinyl Acetates - kinda like fancy elmers or wood glue.


Later they used polyepoxides - no cutting through that stuff! Patent 3,265,234 from Union Carbide spelled the death of PVA resins, I imagine.

Cheers,

agitation, I will see what I can do on that, will look for a small cheap pump.

I was also thinking of some tooth picks stratigically placed around the edges too apply a tiny bit of pressure, and open up the pva to more water.

I may keep the mounting hardware on mine to keep it elevated up a bit. Then I can watch for the glass to fall off! :D

It's actually of the family of Polyvinyl Acetates - kinda like fancy elmers or wood glue.

Cheers,

Polyvinyl acetate is soluble in VOCs... I wonder if acetone might help then. (or ether if you can get it, but it's a little less "safe" to work with.)

I've tried several things: acetone, methyl alcohol, grain alcohol, stripper, spirits....

Nothing touches it, nothing. I always resort to chipping the lens off with a screwdriver, since I use tubes in sets with flat glass anyway.

I've tried several things: acetone, methyl alcohol, grain alcohol, stripper, spirits....

Nothing touches it, nothing. I always resort to chipping the lens off with a screwdriver, since I use tubes in sets with flat glass anyway.

In light of that I'd suspect there are numerous additives they put in it to get it to bond to the glass; those additives must be what solublizes in the water and also keeps things from easily eating away at the PVA.

I can def see the little stress fingers around the edges where the toothpics are. Just have to be careful handling it with all the water making for slippery handling...

I wonder if there are any chemists on VK or ARF that would be willing to research the possibility of designing a coumpound to disolve PVA in a comparable amount of time to the risky heat method?

Tom C.

Trouble is anything that's going to work well is also going to be very nasty, and leaving something like that open is a no-no.

Trouble is anything that's going to work well is also going to be very nasty, and leaving something like that open is a no-no.

Agreed. I'd further suspect that trying to dissolve the PVA will leave you with a nice gummy mess on your tube and safety glass... If we can find out the bonding agent that is affected by the water, it may be possible to do better. I wonder if it would make a difference to gently heat the water to say, 40/50 degrees C. Not too stressful for the tube, and if done slowly, it allows a thermal gradient to establish with minimal stress.

Zenith comes close with their patent for reducing thermal gradients during CRT "salvage"

How about Acetic acid for a solvent? PVA glue (Titebond wood glue) reacts to the stuff....someone with salvaged PVA could possibly test the theory.


Cheers,

Seems like if you used a solvent it would result in a gooey toxic mess to clean up. Thats how the Zenith green halo ones are, its like jello that smells like a combination of sewage and used crankcase oil.
I avoid the Zenith ones now because cleanup is so time consuming. Yea you can cut the window off in 20 seconds with a piano wire, but then spend a week trying to get that goo off.

I have a piece of pva, ill try some solvents when I get time but still think I would prefer water.

So, stick the tube in a vat of vinegar?

If it was pure PVA, then vinegar might work... see here:
http://www.ehow.com/how_5650421_dissolve-wood-glue.html

Worth a shot, I guess.

Edit: Glacial acetic acid would be more potent... but harder to get a hold of. You could probably make some by distilling or concentrating vinegar, depending on the acetic acid boiling point.

dumped in 1/2 gal of vinegar...

DO NOT dump glacial acetic acid into a pool like that (if you happen across some). If the smell doesn't blow you away (it can damage the lungs) it will likely dissolve the pool. A half gallon of vinegar probably won't do much of anything, but hey, it can't hurt, and it's cheap enough.

I remember seeing a posting with pictures of this kiddie pool submersion method, and they stuck popsicle sticks into the edges of the pva as it worked loose. It did a great deal to speed up the process.

I can see that I will have to keep an eye on it for evaporation losses.
You can make a little tent with a blue tarp or taped-together garbage bags. Could help with smells, too.

Phil Nelson

I recently learned, to my surprise, that glacial acetic acid is flammable.

The article on reducing stress is very interesting, but it deals with faceplate removal from the bell by melting the frit which involves much higher temperatures.

I suspect that the problem with the heat method isn't thermal stress, but that the PVA or other material has plasticizers in it. With PVA it's probably water. When you heat it the plasticizer becomes a gas and when trapped makes a high pressure between the cover glass and the face of the tube.

I seem to remember in an earlier cataract removal thread someone saying that bubbles would form as they used the heatgun.

John

well something is getting nasty, the water is def getting murky looking, and I am seeing life forming in the way of little larve looking nasties, yuk...

See if they eat the PVA. hahaha

See if they eat the PVA. hahaha

That's an idea, put the beasties to work!

They might be mosquito larvae-it's the right time of year for them to start coming out. Whatever they are, they are pretty tough to tolerate all that vinegar. Maybe throw one of those mosquito poison cakes into the mix-you don't want to see how many can breed out of that pool.

They might be mosquito larvae-it's the right time of year for them to start coming out. Whatever they are, they are pretty tough to tolerate all that vinegar. Maybe throw one of those mosquito poison cakes into the mix-you don't want to see how many can breed out of that pool.

... and watch the safety glass fall right off the instant the poison hits the water :D

Seriously, be careful doing that, you don't know how it would react with the vineagar.

I just pluck them out and let them dry up. I think I have a toxic enough soup as is. its starting to look like the bottom a hookah pipe.

Don't drink the bong water.

Put a bottle of cheep vodka or a cup of gasoline in there. Lets get this party going

maybe can find some mad dog 20/20 to pour in.

maybe can find some mad dog 20/20 to pour in.



:puke:

today I poked around it some more, the PVA seems a bit more pliable now. It was rock hard when this began, but somewhat rubbery feel now on the bits I pulled up around where I had jammed in the wook sticks.

As I'd posted in an old thread, this works quicker with the "green" stuff Zenith used. Took me about a week with that. I used popsicle sticks inserted around the edge, but do be careful. That safety glass will break a lot easier than you think!

What I saw was that the PVA seemed to absorb the water and swell; it would later dry out and looks something like it did before.

Would it be bad to use regular store bought vinegar undiluted, or is it just too expensive?

I have two 23' rectangular tubes (one Zenith one Airline) which have about 1.5" of greening at the edges, can the popsicle stick method be used o them or, is it only aplicable for more severe cateracting?

I'm considering preforming my first decat on one of these tubes and wonder which of the several methods that I've heard of are the safest and quickest (I tend to have a short attention span, and little patience).

Tom C.

The green is a different animal. Piano wire was used, there is a video somewhere around here done by member CTC17

which of the several methods that I've heard of are the safest and quickest
I haven't heard of a method that is both safe and quick. That's why he is trying this safer-but-slower method.

Phil Nelson

I took out one of the pva chips (which had gotten hard again after being out of the water for a couple days) and have it soaking in some break fluid. I will try some straight vineagar later (have to make a run to the store for that) on another chip.

That was in my pre camera days. Its on my website. Heating the wire is not necessary if you let it sit in the sun and warm up for a bit.
http://boxcarcabin.com/halo.html

I took out one of the pva chips (which had gotten hard again after being out of the water for a couple days) and have it soaking in some break fluid. I will try some straight vineagar later (have to make a run to the store for that) on another chip.

Also talk to your pharmacist - you'd be surprised what they can order, you may be able to get some acetic acid that's a little more potent than kitchen vinegar there. (either to use straight or dilute for less $ than kitchen stuff) You could also concentrate your own, since the boiling point of acetic acid is ~118°C, vs 100°C for water., so the water will evaporate before the acetic acid. (but stick around 50 and do it slow, or your house will still stink like vinegar!)

Today, Cataract removal.

Tomorrow:

Lol

overnight in the brake fluid caused the hardened scrap piece of PVA to crumble very easy. Seems like it may be something to try, just not sure if the plactic pool would hold up to the brake fluid. In order to make the most of it, I think a custom made tank of some kind would be the way to go. Like a metal garbage can lid, so as not to have to use gallons of brake fluid.

i used brake fluid poured in the loose end of the safety glass.turn crt up and support neck so that the face as if it is in the set.pour fluid into opening and let it flow toward bottom.i did this once and it seemed to quicken the progress.a few wooden shims with slight tension created a river for it to flow.this was the next to last one i done.the last one was a heat method and although very fast,i got a little nervous about it.

I would like to let it soak overnight in the brake fluid. maybe some packing tape around the perimeter of the CRT lens, could form up a dam, but I am sure the adhesive would fail quickly and it would then leak out.

Maybe the CRT would fit in a round galvanized tub like maybe something from a feed/farm store.

Keep in mind you are going to have to clean up whatever solvent you use other than water. If you want the tape or silicone or whatever to stick you are going to have to remove all the brake fluid.
Best just to be patient and use water. Mine cleaned up so nice and the silicone is sticking so well.
Good things come to those who wait.

The above post is spam which against VK rules-Please remove-Thanks

The above post is spam which against VK rules-Please remove-Thanks

PM is being sent to mod as your last 5 posts were exactly the same. Your posts are spam.
Maybe a virus or someone got your password...I hope.

Just hit the http://audiokarma.org/forums/images/buttons/report.gif button, and mention spam- the mods will handle it.

checked it this am, there is a radial crack in the pva starting from the edge about 2" long, progress at at last... I will get some pics later. There is only one such crack, I would like to see a few more.

had a nice new deep crack in the pva, I was able to pick out a chunk about
1" by 2".

it would be a nice sized piece to play chemistry on.

I will prob stick in in a pan of brake fluid, maybe a side by side comparison 1/2pan of brake fluid pan 1/2 pan of water.


Water does the trick you just need to be more patient than the owl on the tootsie pop commercial...

I picked this up in January, let it soak in water for 2 months, today, nice and sunny in NY, put it out in the yard, the mask literally popped off in about an hour. Ive heard someone say that patience with these things is the key. cheers, Bruce

nice series of pics, you can see the "fingers" working across as the pva releases. I could prob do the same to mine now, I just dont have a decent way to hold the CRT in place (for the sun bake).

Hey Dave, i, as you can see, just used a standard garbage can with some 10 lb weights in the bottom so it wouldnt be too top heavy and let it do its thing. In the beginning i wasnt so patient though, i kept looking every day to see if the water was working and eventually just forgot about it. The tube tests good, however, and now i just have to install it and see how it goes. good luck buddy

roger that. FYI I have made my stockholm my daily watcher, The old CRT is working well. I never retested it after the inital check out where it tested weak.

The one I am soaking test very good so I am looking forward to getting it done and will install it in the stockholm (will then do the process on its crt which is also needing a de-cat.

Are you planning on reintstalling the lens? I have a CTC7 that will prob get the next CRT I de-cat, that way I dont even have to worry about reattaching it.

actually the last picture in that series of photos i posted is the tube with the lens re-installed, i used the strips of foam tape and taped up the sides with some clear packing tape. Im glad that youre getting life out of that Stockholm. I just moved into a bigger house and mine is the daily watcher and the center of the living room, its just so damn cool looking...Bruce

oh yes I bet folks say "wow nice color I did not know they looked that good" when they see yours, I get that a lot. I have another CTC-16 that needs a new cabinet that I hope to put in a bedroom, its vertical (speaker on the bottom) so up a little higher for better viewing. I am also digging on the phono and stereo, when there is nothing on tv to watch.

:thmbsp:

Did you silicone that one or just tape it? Im not a fan of just taping it, the dust is going to find a way in there. The GE silicone 1 works very well and adds alot of strength to the glass. You can always cut it off if you need to.

I will give it a try, thanks. Having only done this a couple of times, i figured if the side was taped it would be good. The silicone sounds like a good idea though.

Tape kinda drys out and flakes off especially in a hot dry environment like a tube tv. The way hawkeye did it was used a solid ring of the double sided tape with no gaps, his tape is more like weather stripping. I went with the bead of silicone because I never want to remove the crt for cleaning.
Its all experimenting, trial and error and learning. There really is no wrong way unless you break the glass.

Done...

I got tired of waiting so I put in out in the sun with a few chop sticks around the perimeter, about 45min total and it popped off.

I have a few scratches on the lens (not the CRT) that I have to deal with, I dont know how they got there but they are there and right in the field of view.

anyone have suggestion on scratch removal? I was going to head down to the auto parts place to see what products they have, or maybe just take it to a auto glass shop and see what they can do.

another one done, 20min tops.


This was one of the green cats found on zenith tubes. I put it in the sun for about 15min, then used some SS saftey wire (.007 IIRC) and looped it around the perimeter just under the lens. I tied it off with enough space to get a thick piece of card board under it to protect my hands. then just started pulling. It cut thru the gelitin consistancy plastic goo. Once I pulled it completly thru the lenes lifted off. Most of the goo stuck to the lens, very nasty stuff. I next put the lens in my wading pool (in the shade so the water is cool), and the goo quickly set up. allowing a pretty clean pull off (was like rubber coming off after cooling). the lens will still need some cleaning but its 95% goo free now.

Bottom line is the green is easy but a bit messy, the white is a bit more of an effort but pretty much mess free.

Another successful cat removal. I have a 21FJP22 that had a pretty severe cataract.

http://i642.photobucket.com/albums/uu143/ampico-kid/RCANewVistaII2.jpg


I decided to try the "water" method and plopped it face down into an overturned garbage can lid. It sat there for about 3 weeks.

Today I wanted to see how much progress I made and pulled the tube out of the water and turned it over and placed it into a plastic recycling can. It's a perfect fit and a stable way to hold it. I then took several wooden paint stir sticks and began to push them in between the tube face and the safety glass and sat it out in the sunlight for a while.


http://i642.photobucket.com/albums/uu143/ampico-kid/CopyofDSC_0736.jpg


I started to notice the safety glass showing signs of release from the bonding agent, and over the coarse of the next hour I slowly pushed the sticks in further and further. After about an hour I could see I was getting close.


http://i642.photobucket.com/albums/uu143/ampico-kid/CopyofDSC_0739.jpg


All of a sudden the sticks all fell to the ground and I picked up the safety glass off of the face of the tube.


http://i642.photobucket.com/albums/uu143/ampico-kid/CopyofDSC_0741.jpg


http://i642.photobucket.com/albums/uu143/ampico-kid/CopyofDSC_0743.jpg



I then carefully peeled the bonding agent off of the face and that was it. Done.


Here's the bonding material after removal from the face of the tube.


http://i642.photobucket.com/albums/uu143/ampico-kid/CopyofDSC_0746.jpg


It took just three weeks to accomplish. Patience does pay off in the end.

Bob

yep. same thing here. I watched the bonded area start going fast until it was about the size of a dime, then a pretty loud "pop" and it was done.

Nice job you yours.

dont want to be premature in case someone else has a better way,but, i think we got the way to do this......

the green goo remnants were cleaned off with some gasoline, looks good, so I will use this lens for the good roundie since the one I popped off had a bad scratch in it. The plan is to seal up the tube with the lens (maybe tomorrow) and then to install in the stockholm. the stockholm tube will be de-cat and will be a spare, or will go into the CTC-7 table top (metal cap faux wood finish) if that chassis is fixable.

Nice work guys and thanks for the pictures. Hopefully I'll be giving this a go here myself soon. We're having a real hard time transitioning into spring, seems it's been snowing most every week in April. :sigh:

I wonder how much the water soak helps, or if it's mostly the sun doing the softening?

I wonder how much the water soak helps, or if it's mostly the sun doing the softening?

I think the water is an integral part of it. Before I started the water soaking the bonding material was quite hard and very difficult to penetrate. After soaking in the water it was very pliable and rubbery feeling. It would be extremely difficult to get the wooden pry bars in there unless the stuff was soft enough, and I think that's where the water comes into play. The day I put it out into the sunlight, it was still pretty brisk outside. I felt the screen and it was just warm to the touch, so I don't think the heat played a major role in the release. Bob

update the wire I used on the green cat to slice thru the goo was a .02" not
.007 that I thought.

I have some CD scratch remover I plan to try on one of the smaller scratches. Also picked up some foam 3/16 wide by 1/4 thick stick on window seal. I plan to use that to space off the lens from the CRT.

Given the chemical composition of the PVA, I don’t see why 30% acetone in water would not work. The key is distilled water. Who knows what is coming out of the garden hose? I have well water that is hard as a rock (because it is a rock) 51 grains of hardness. It turns brown overnight with all the iron in it. Mix it with my soft water and the sodium will tie up the acetone and nothing will happen. I did get a laugh out of many of the responses. Don’t drink the bong water! ;)

I take it you live in the "love canal" area. You should check if the water is flamable. you never know you could save a mint on gas. LOL.

Tom C.

Wonder if a little dish detergent in the water would help. That would relieve the surface tension and make the water penetrate better. Also, if the water were warmer. I'm envisioning a pan elevated on some bricks making an "oven" with a light bulb underneath to keep the water warm.

I'm waiting until we start to get into our hot summer months!

just a note, if you decide to use pressure to finish up the job (as opposed to waiting another month for the lens to just fall off), I would consider what others have said, the glass will crack if too much is applied. You dont need to see any movement when inserting spacers (chop sticks in my case) just snug them in to a void (which will be easy to make as you can pick out around the perimeter the softened pva). I gently tapped them into the voil until it sounded "solid" then walk away for a few min, observe the fingers starting to form, go around the perimeter again and tap to make sure still snug, walk away, repeat. It starts slow but the last 25% of the contact area goes very quickly, with a satisifing "pop" as it finishes up.

In my case it was a very sunny day, maybe 85, the glass was quite hot, I should have used my IR gun to check it but a ruff estimate would be 120f