cullet updates?

[neil duman]

Back to Cullet.
We are thinking of switching.
Would like input from anyone who has used a cullet recently.

I prefer one that fines out reasonably well without cranking the furnace up above 2100, doesn't discolor when torched and has a decent working time before reheating.

I had been batching for years and am not interested in batching again.

[Pete VanderLaan]

2100 is unlikely to be workable for the demands you have. It's simply too cold unless the possibility of pre heating your cullet exists.

Otherwise, no one is raving about any cullet out there that I'm aware of. Choose from the best of a bad lot.

[Art Freas]

We are liking the Bomma, but you have to load a bit different than some of the others. It is fairly long working, great except some times a little longer than I would like for product runs.

We load at 2150, we run at 2150 as well. The thing to keep in mind is that you need to load more frequently and not get the new layer very thick, if you load a lot at one time you will have a lot of small bubbles. So you can't say 25Kg is ok or 50Kg is ok, or 10KG is ok, depends on the size of your crucible. We load most nights and if we have used a lot try to catch up a bit at a time not just a lot in one night. We just make sure we don't have a really thick layer of new glass.

[Mark Rosenbaum]

I am using Kugler in a #400 pot electric Stadelmelter. We like the results. We keep the temp at 2050 working and melting. We can throw in 2-#50 charges an hour apart and have good glass in the morning. We do that 2-3 times a week. The qualities are pretty close to Spectrum. You have to turn your flame down to fire polish or it will brown.

[Brice Turnbull]

Hi Neil,
I have used the system 96 nuggets (+ or something, can't remember the designation for the 2nd generation), oceanside, kristalica, and am now using bomma. In a distant past I started with Gabbert cullet at college, and used spruce pine batch (mostly 87 with erbium) for about a decade also. I have always worked from a wire melter furnace, which maxes out around (?) 2080 (?).

My favorite cullets for fining at working temp are kristalica and bomma. I found them both to take about 3 days to fine to very clean, but were both quite usable for blown ware on day 2, showing a sparse matrix of fine seeds.

My best results for clean glass come from small scoops into the furnace every 3 hours or so, and I try to put in a flat layer all over, not always just dumping a mound in the center, which will usually add 2+ days to wait for clean glass. My working temp is cold. Probably 2000, or even 1975, to lengthen the life of my elements and make bigger gathers more easily. Naturally, I don't know the actual temp of the furnace interior, as no one does. This is why I give a range and question marks.

edit to add: Ha! I wrote this before reading the other replies, and it's interesting to hear Art's experience with the wide layer of cullet also.

[Michael Ahlefeldt-Laurvig]

Everybody that wants to know the temperature of hot things get a 30 dollar IR thermometer