CRT Panel Glass

[FlashGP]

Here’s one for the brains trust.  I have some CRT panel glass from the front of one of the large late model colour TVs.  I collected it from the roadside in about 2013-15.


I’ve done some research and have found the panel glass contains no lead, instead TV crt manufacturers used Barium and strontium oxides for radiation shielding in the front panel, mainly for the optical properties.  They used varying amounts of lead shielding in the funnel and neck glass, the neck glass containing less lead.


The panel glass I have has a density of about 3G/cc.


Does anyone know roughly what the refractive index of colour TV panel glass would be.  I know it is reasonably high but haven’t found anything from the literature.  All the data based on density is for tungsten and barium oxides glass by density.  It focussed mainly on recycling TV crt glass for radiation shielding such as x ray labs, nuclear reactors, space craft.  Strontium has a different optical characteristic.

[MakkyBrown]

If you want some glass, did the research and is lead free a while ago, you pay the postage and I'll send you some as I'll probably not cut much of it again. There was also heap in a container in my front yard will have to look I might have thrown it out. It was from a big 90cm panasoinc and fairly think.

MB

[MakkyBrown]

I have heaps(at least 5kg) it is 15mm thick. Anyone that wants some pay postage. It is a light grey colour.

MB

[MakkyBrown]

Reckon you should be ok with the glass. RI would be around 1.6 at a guess.  Most screen glass should be ok, I'd avoid the tube/neck glass. I did quite a bit of research on the glass in my tv but that was a while ago.
MB

[RoughCreations]

There's also this thread:
https://aussielapidaryforum.com/forum/index.php?topic=6473
RC

[FlashGP]

Makky, I would be interested in seeing some empirical data on heavy metal leaching from glass heavy metal compounds. 


It seems 24% lead glass is deemed safe to eat and drink from (eg crystal glass ware) so I’m a bit perplexed as to why the heavy metal in glass is considered such an environmental problem or a danger to Facetors as the heavy metals and glass form a compound. Contrast this to gold leaching where the gold is tiny particles among a rock and not a compound.


When I was studying science in the early 1980s researchers were investigating making glass with nuclear waste as a way of trapping the waste so it won’t leech into the groundwater when buried.  I don’t know of the outcome of that study.

[MakkyBrown]

Just looking at your pic RCs. The yellow high Pb sample certainly has a more appealing colour. I find the grey stuff pretty boring.
MB

[RoughCreations]

Yeah, the grey stuff might be better for some frosted designs, or a briolette..
I found and uploaded those images to the Gallery. An early post of mine where I put the images on the net, to accidentally delete them a few years later.

[MakkyBrown]

I have lots of long thin bits if you want some for briolettes.
I've being cutting some Killicrankie topaz, in Six Star Brilliant from the beginner Book (download link of the forum home screen) looks superb. Nice amount of sparkle through the full tilt axis, table windows a bit as it tilts but is not really that noticeable due to the moderate table size. Highly recommend it.
MB

[RoughCreations]

I'm cutting Frost Star Hex 2 (Volume 5) in a big slug of Gladstone citrine. Haven't cut a big quartz in a while, feels good.

RC

[FlashGP]

Hi after attempting to measure the RI by shining a Ryobi  laser level (the simple one with one beam that fans vertically) I ended up with a different RI depending on the angle I shone the beam at, ranging from 1.6 to 2 ish.


So I ended up trying to calculate the critical angle by finding the angle at which the beam hitting the back wall of the sample reflects along the side rather than exiting it.  The literature on this specified the beam had to travel from the more dense material (the glass) to the less dense material (air).


I ended up measuring 33 degrees so chose a mid RI from the selection of gem material with a CA of 33 degrees, RI 1.9 and optimised and cut the Open Challenge in this year’s comp in the panel glass at that RI.  It worked well so I think I’ll use 1.9 for this material.


I’ve run out it refractometer fluid so it would be useful developing a way to accurately measure RI or CA using a cheap led laser.  I’ll need to adjust for the wavelength of the laser, something I didn’t do in my early attempts.


This would be useful for high RI material as the cheap refractometers stop at RI 1.8