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Old 04-27-2019, 12:51 PM
Sean Jones Sean Jones is online now
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Telux cullet

Does anyone have experience with cullet from Telux in Germany?
Iíve been using it in my wire melter in the UK. Bought it from Glassworks Services as White Water Nuggets (pucks about 2Ē diameter). Itís been good, apart from the popping during melting, even though I preheat. My problem is lack of experience as Iím learning so I donít know if I would find Cristalica easier. Too easy to blame the glass!
The composition is given on the Glassworks Services site as
SiO2 73.12% Al2O3 0.762% Fe2O3 0.007% CaO 7.420% MgO 0.142%
BaO 1.592% ZnO 1.605% K2O 4.607% Na2O 9.932% Li2O 0.674%
SnO2 0.006% Sb2O3 0.105% SO3 0.013% TiO2 0.012%
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Old 04-27-2019, 01:39 PM
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Pete VanderLaan Pete VanderLaan is offline
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At that size, preheat the little slugs.
I've not heard of the cullet but cullet is undergoing a balkanization right now.
Test some small samples against the color you use
.
Googling it, I can only come up with Telus cullet, so you may have to put up more complete info. Glassworks services lists itself as supplying Kugler which is now making clear cullet that, as you say, explodes in the pot. Perhaps it's the same material but their website doesn't mention it.

It's quite high in silica and rather low on alkaline fluxes. I would expect it to be sort of short which is one of the observations about the kugler stuff.
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Old 04-28-2019, 01:01 AM
Sean Jones Sean Jones is online now
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I asked them about Kugler but they feel that itís too expensive. This stuff is comparatively cheep. I only know itís Telux from the label on the bags it came in.
As a beginner I imagine I need a long glass. I can live with it eating the crucible, Iím making clay 40# pots which crack after 4 or 5 heats anyhow.
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Old 04-28-2019, 06:28 AM
David Schimmel David Schimmel is offline
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I suspected it was in Germany and search for Telux Glas, instead of Telux glass and found Telux is located in Weisswasser, Saxony near the Polish border.

https://telux-glas.de/en/home
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Old 04-28-2019, 08:53 AM
Shawn Everette Shawn Everette is offline
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What are you using for a furnace? Sounds like you're being pretty rough on the pots.

As far as working time, as long as you're not using bottle glass you should be fine. What's the price point on the Telux.
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Old 04-28-2019, 09:42 AM
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"Iím making clay 40# pots which crack after 4 or 5 heats anyhow."
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Making your own pots is yet another artform. In England, Dyson pretty much has a monopoly unless you want to go on the continent and get Fafnir. Any pots I've ever made were kyanite and ball clay. They were great as long as you never turned the furnace off. Then? It's gone.
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Old 04-28-2019, 04:17 PM
Sean Jones Sean Jones is online now
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I made my melter, it has as much Wire as I could get in and an SCR. An inch and a half from the elements to the crucible wall. 5Ē to 6Ē of frax, 4kW holds 20kg of glass.
I live in the potteries (Stoke on Trent) so pick up bags of heavily gorged stone ware originally produced for making saggers (the containers that protect pots in a kiln). T Material from Thermal Ceramics seems best but is about $70 a pot (10kg). The cheeper brands are about $25 a pot. Takes me a total of 2 hours to make a pot. To buy a pot Iím looking at $400.
The Telux cullet is $1 per pound (£1.50/kg in real numbers).
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Old 04-28-2019, 06:06 PM
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Keep your grog content high. Use any higher alumina clay compounds you can. Expect failure when you shut down, but not on just running. China clay is your friend. The cullet you are getting is a means to an end. . It's a tool. no more.

When you need better tools, it will likely come from a visit with a friend who opens your eyes.
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Old 04-29-2019, 02:51 AM
Sean Jones Sean Jones is online now
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I think my pots die in the silica inversions on the way up. I once heard one crack in the middle of the crystobalite range. I take 53 hours to heat up, 5 deg/hour through cristobolite and 10 deg/hour through the quartz inversion.
The cracks are annular round the base. Iíve changed the shape to make the bottom more rounded and cut deep grooves in the plinth to allow more heat to get to the base.
We have a wood fired furnace we run for a week in summer. We have to let in cool somewhat between firings (we have to sleep) so I invest the bottom of the pot to stop it leaking. That seems to work well.
What temperature is it safe to drop down to for several days without devit?
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Old 04-29-2019, 09:29 AM
Shawn Everette Shawn Everette is offline
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Are you stilting your pot? If not that might be part of your cracking problem, bottom of the furnace pulling too much heat.

My up cycle it typically 4-7 days, but I've got a 500lb tank. There are some crucial hold step that I try to hit at 900, 1250, and 1600; so a few soak steps may help as well.

I've held tanks as low as 1550 without much issues, but devit is always dependent on your glass. Typically is I'm holding a tank for later I keep it about 1800, nice thorough squeeze and can be back up almost instantly.
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Old 04-29-2019, 10:07 AM
Sean Jones Sean Jones is online now
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Using stilts sounds like a good idea. Iíve not come across that before.
Your hold temperatures are also interesting. I assumed that once I was above the quarts inversion at 1070F I was safe to go up fast.
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Old 04-29-2019, 10:34 AM
Shawn Everette Shawn Everette is offline
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All free standing pots I've seen are stilted with hard brick, it allowed the heat discrepancy at the bottom of the pot to be not as drastic.

From my experience you want to take it slow to about 1500F. Quartz inversion is a key factor, but there is still changes happening past that point. I don't l know that the pots ever get to the full vitrification stage, but there has got to be shrink.

Another thing you may consider is a different furnace configuration. A frax design is going to be a complete heat dump no matter mow much you have. The SCR is going to help with maintaining accurate temps, but even soft brick is going to allow for much better heat retention and gentler cycle. Hard brick or castable would help even more, and will resist corrosion better. Frax is fine for holes or kilns, but furnaces should really be made from a denser material. There's an excellent chapter on R factor in Glassnotes.
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