Bomma and Antimony

[Art Freas]

Noticing that the Bomma does not respond as much to a squeeze as much as the Cristalica and the Spectrum did. Could this be because there is less antimony in it making the valence switch?

[Pete VanderLaan]

well, about a gram per lb of antimony is what would normally go into a glass batch. If there isn't sufficient antimony, that could be the issue. Viscosity could have an effect as well.

[Eben Horton]

Art,
There was a bad batch of Bomma sent over here and it drove a lot of glassblowers nuts because it wouldn’t fine out. I suspect you have some of that batch if you are having troubles

[Art Freas]

No serious problems, just seeing different behavior and curious.

[Shawn Everette]

You got a production date on that?

I'm about to the end of the stuff I bought June '19 with a March '19 bag date. The stuff I just bought is from May-July '19. Sure doesn't seem like there moving through it that fast.

[Scott Novota]

I just got some recently and it is the 07/21/2019 run. (shipped from Atlanta)

It fines out just fine for me at 2150f and walking away and doing nothing else. I am just giving it a run to see where it falls compared to SP and how much of a difference it makes in how I work/time. If I was wire this would be what I used. Right now I am on the fence. It does need to work a bit hotter than SP and has, to me at least, a slightly different lockup on the backend. Other than that decent glass.

Furnace: Moly: 2150f load up, put it about 20lbs every 45 min until full. Blow the next morning no issue and never touch the temp. Work it at 2100f. I worked SP at 2050f.

I think I am going to ask for Pete's mix next time and see how I like it. Hell I might even mix my own if I could find a decent silica supplier.

Originally Posted by Shawn Everette

You got a production date on that?

I'm about to the end of the stuff I bought June '19 with a March '19 bag date. The stuff I just bought is from May-July '19. Sure doesn't seem like there moving through it that fast.

[Pringle Teetor]

Does anyone have the number on the bad batch? We spent 2 months trying to get the stuff to fine out and gave up.

Originally Posted by Eben Horton

Art,
There was a bad batch of Bomma sent over here and it drove a lot of glassblowers nuts because it wouldn’t fine out. I suspect you have some of that batch if you are having troubles

[Pete VanderLaan]

Pringle,
You just seem to have the plagues of JOB when it comes to getting bubbles out of things. I had never heard of any bad batch issue with BOMMA but I did find Charlie Parriot in what I would call less than a forthcoming mood whenever I've talked to him about it. Does the cullet have bubbles in it to begin with?

I don't know why it is so seemingly difficult. SP87 made a fine cullet as far as it goes but had the failure of the furnace as an issue. There are commercial furnaces out of South Korea that will handily melt a ton a day without issues for about 50K. The work appears to be ladling it out to turn into the cullet. Now, after two years it seems like the problem has not resolved. You still can't make money on it given the current pricing and that's dangerous.

[Art Freas]

Pringle, that is so strange. I will check my bag dates this week. They are from 2019, I think from Oct 19. I did have some seed challenges when we first loaded the pot from cold. Will filled it cold and then brought it up slow, then topped it up. Doing it again I wouldn't load as much at first. would load slower in small layers. We used to load once a week but now we do it a little most nights just keeping it at our working temp of 2150 (with a side thermocouple). After the first load they eventually worked out but it just doesn't respond to a squeeze the same as the cristalica or Spectrum Sys 96.