CRT implosion experience?

[Findm-Keepm]

Originally Posted by jr_tech

If the bonding material on a particular tube is a type of polyester resin (I believe that some were ... PPG 5252 or something like that), methylene chloride will do the job. Very nasty, however.

jr

Dow Chemical's formula is in Patent 3007833:

33 parts by weight diglycidyl etherr of bisphenol A, 67 parts diglycidyl ether of polyoxypropylene glycol having a molecular weight of 400 and 5.5 parts of monoethanolamine and 1 part of diethylenetriamine.

What that means, I dunno. The patent is for the use of a Saran wrap band around the tube and safety plate while filling the gap with the above mix.

US Patent 3265234 from Union Carbide lists a number of other chemicals that were used to bond the safety plates - about 4 or 5 formulations are compared.

I guess not all CRT's used the same bonding materials....


Cheers,

[jr_tech]

Originally Posted by Findm-Keepm

I guess not all CRT's used the same bonding materials....

YES! I think that is the reason for some frustration on this board... methods for dealing with one type of bonding material may not be effective, and perhaps even dangerous to use to remove another type.
Dow Corning 184 for example, was sometimes used on smaller special purpose tubes where high optical quality was desired... I suspect that heat alone would not be effective to remove a faceplate bonded with 184.
jr

[jeyurkon]

Originally Posted by jr_tech

If the bonding material on a particular tube is a type of polyester resin (I believe that some were ... PPG 5252 or something like that), methylene chloride will do the job. Very nasty, however.

jr

Really nasty and dangerous. It has a high vapor pressure and will evaporate very quickly. It would have to be a very valuable tube before I'd try it.

Originally Posted by jr_tech

YES! I think that is the reason for some frustration on this board... methods for dealing with one type of bonding material may not be effective, and perhaps even dangerous to use to remove another type.
Dow Corning 184 for example, was sometimes used on smaller special purpose tubes where high optical quality was desired... I suspect that heat alone would not be effective to remove a faceplate bonded with 184.
jr

I'm not sure how you'd do that either. I still have a scar from trying to remove a PMT from a light guide that we wanted to save that had been bonded with Dow 184. Have you ever seen a cataract or similar form with 184? I'd expect it to last nearly forever. Rebuilding a CRT bonded with it would be a real bear. A long term soak in trichloroethylene would swell the 184 and loosen the bond, but is also hazardous.

Dow 184 is nearly ideal for the purpose, but would break the bank for a large CRT.

[jr_tech]

Originally Posted by jeyurkon

Have you ever seen a cataract or similar form with 184? I'd expect it to last nearly forever.

Yes, I have observed partial de-lamination on some tubes using 184.... sort of looked like "worm tracks" in the material.

Originally Posted by jeyurkon

Dow 184 is nearly ideal for the purpose, but would break the bank for a large CRT.

I see that Amazon has the material listed, wonder how many 21" crts could be bonded with an 3.9kg "kit" for $336 ?

jr

[jeyurkon]

Originally Posted by jr_tech

Yes, I have observed partial de-lamination on some tubes using 184.... sort of looked like "worm tracks" in the material.



I see that Amazon has the material listed, wonder how many 21" crts could be bonded with an 3.9kg "kit" for $336 ?

jr

Guess it would depend on the bond line. If it was 1/8" you could do about five 21" CRTs.

John