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-   -   Bomma and Antimony (http://talk.craftweb.com/showthread.php?t=12663)

Art Freas 08-31-2020 03:55 PM

Bomma and Antimony
 
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 09-01-2020 08:51 AM

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 09-01-2020 10:58 AM

Art,
There was a bad batch of Bomma sent over here and it drove a lot of glassblowers nuts because it wouldnít fine out. I suspect you have some of that batch if you are having troubles

Art Freas 09-01-2020 11:07 AM

No serious problems, just seeing different behavior and curious.

Shawn Everette 09-01-2020 12:22 PM

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 09-02-2020 11:44 AM

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.


Quote:

Originally Posted by Shawn Everette (Post 148651)
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.


Art Freas 09-02-2020 11:53 AM

Works really well for us. My learnings on it are. Don't count on a squeeze, just doesn't squeeze much. Don't batch in any depth, deep batching equals seeds, shallow batching equals clear. Don't batch once a week, see the depth thing. Batch when you need it. If you run way down, work your way back up over a couple of days. We keep it at 2150 and if we have a little more than usual to batch run it up to 2175. From the experiences others are having we never take it above 2175 (haven't needed to) as some folks have seen some cords when going really hot. It is really nice stuff, just behaves different than the Sys 96 studio nuggets and Cristalica.

Shawn Everette 09-02-2020 12:37 PM

It's been great for us so far too. I actually prefer it being a little shorter than spb for my production stuff, don't have to wait between steps for it to cool. Still longer than spectrum/oceanside or cristalica. They've kept the price drop after that bad batch, so it's kind of hard to beat at the moment.

Technically we are cooking and using it "hotter" at 2175 in our new furnace, but that's because of the thrmo being mounted on the side vs the top. We're not getting the same 'heat" we used to, the color is just not right at the old 2080.

Art Freas 09-02-2020 03:34 PM

Our thermocouple is on the side as well. We have a gas englesby design furnace.

Shawn Everette 09-02-2020 04:57 PM

Ours is a wet dog, nearly identical to what we had, other than where the thermo was. When it was on top running at 2080 had good heat color and consistency. When we got the new one up it was way too dark and viscous at that temp.

I also feel like when it was on top there was less of a registered temp deviation whenever the door opened. It doesn't have to do with tuning it, runs as it should, but rather the pocket of air along the crown acted as an insulator as air came in. It's way snappier at kicking up the blower.

Pete VanderLaan 09-02-2020 05:06 PM

If you do get mine, get it as a snowflake. Amazingly, I haven't made glass since last Dec and left the furnace half full and I never shut it off. I took a gather today and it was perfect. That really surprised me.

It's a great glass, really. I don't get a dime out of it.

Eben Horton 09-02-2020 05:53 PM

Quote:

Originally Posted by Pete VanderLaan (Post 148670)
If you do get mine, get it as a snowflake. Amazingly, I haven't made glass since last Dec and left the furnace half full and I never shut it off. I took a gather today and it was perfect. That really surprised me.

It's a great glass, really. I don't get a dime out of it.

Why would you do that ????

Shawn Everette 09-02-2020 09:16 PM

I believe he's referring to your furnace...

Pete VanderLaan 09-03-2020 07:27 AM

Available time always seemed just around the corner. But as the outlets closed up I used to sell in, the pressures to make work diminished. I still needed to keep the pipes from freezing and there is something about a glassworks with no background noise that I've always found really disconcerting. As COVID expanded, we became a very different couple trying to focus on staying healthy. Another month would pass, the furnace throttled on low. I have felt for some time that my time at the furnace was over but leaving it on left possibilities. It's still the case. I'm very fortunate now that I no longer need the income from the studio. It's certainly not a common experience.
I find the politics of our future riveting for me and it has totally thrown me off in my focus.

Shawn Everette 09-03-2020 10:04 AM

That silence, is haunting. Even if things were shut down properly, if I enter the shop the first thought is "what's wrong". After a week or so I get used to it. Diagnosing things by the hum of a room is a "special" gift.

Art Freas 09-03-2020 11:34 AM

The COVID shutdown hit three weeks after we restarted our furnace after a total rebuild and shop renovation. The silence was a total bummer. It was very hard to be in the quiet shop.

Pete VanderLaan 09-03-2020 11:35 AM

Back on Bomma.

I have been surprised at the cool reception that the Bomma has gotten. I am continually surprised to hear how many people continue to use Cristalica and surprised by any willingness at all to go to Oceanside. It seems to me that the product that has really benefited from these shortages has been Spruce Pine Batch Co.

Shawn Everette 09-03-2020 12:00 PM

The last shortage caused a lot more shops to reconsider spuce, or just be in the bind that it was batch or nothing. Bomma was unheard of, cristalica had been hit or miss, and oceanside really stumbled the transition. I was able to mostly coast it out because we buy our year supply ahead of time, helps keeping your feelers out to know what's happening supply side.

My old shop that had probably been on cullet for 10 years switched. I think it helped that spruce had started doing the small bags, expensive, but that did seem to keep down the dust significantly. I think overall it was also a good move for them because they ended up switching glasses every 2-3 years. A key factor in that was having to order every 6 months or sooner and take whatever was on hand.

Scott Novota 09-03-2020 04:35 PM

Pete,

I will give your batch(snow) a run when I pull out this pot. If I am going to a new clean glass I want a clean start.

Gonna finish my run on this one and try to kick up that purple we made years ago at your place as the last drop in this old dog of a pot.

Pete VanderLaan 09-03-2020 07:27 PM

we put the batch in 5lb bags back in the first color class, which tom took so we could get batch into 7 inch pots. That was the sole reason. I continue to view the notion of dust in batch as candy ass. Put on a mask for fifteen seconds. It's no big deal, or sweep your floor, it's about the same.

Shawn Everette 09-03-2020 10:26 PM

I can't say as I actually had a problem with the dust in batch, but it was a sore spot whenever I brought up moving to spruce. They supposedly at one point had a "batch room", where "volunteers" would move batch to little bags for charging. Apparently that was just a shit storm for dust, and not in a sealed environment. I'd say the worst I've had was having to shovel it out of a trash can. That was prone to dust, even when it's pellitized.

Pete VanderLaan 09-04-2020 09:35 AM

If you went to big factory charging systems, North American Rockwell had build screw type charges with an auger. The auger turned and loaded the batch through the door. A big Trojan Horse on wheels with a gaping maw. Pelletizing batch was only done at Phillips and they mixed a calculated charge mixed with sodium silicate to harden the stuff into little balls. I don't know when Phillips started that.

I've always thought the dust issue to be a specious argument. If one balanced the very fact that most shop floors were horribly underventilated I suppose you could make the argument but if you looked things like boron in the cullet, there was virtually boron everywhere. Look at the windows and see the etching.

I would continue to say that cullet was easier than batch bad as the cullet was, just in terms of time before the glass was ready to be used. Keystone cullet, once excellent was by this time .02 cent trash. Peiser was already making his own glass by '75. At Pilchuck, pre 1971 they really made great glass but the demand for hot stuff and the remarkable ways in which it got wasted were profound. By 1976 when I was teaching up there, Ben Moore had come back from his stint at Veninni and the stripping off of glass after gathering was upwards of 3,000 lbs per week. It was not a glass that took well to remelting. Mark Graham and I would go off to NW glass and fill the back of the school truck once a week and we would watch it getting thrown away.
That required the schools to insist that there were "bubble Chasers" among the true believers and we were to be shunned publicly for thinking glass quality to be important. Keep in mind this was years before Spruce Pine came into existence but at least in the Rocky Mountains, the private shops were making flawless stuff, none of pelletized, all of it home mixed. At one point Dale wanted me to ship him my batch to the shop he was working in at Tucson. I passed.

While I may be well past my "sell by" date, I continue to view it as laziness regarding respect for quality in the basic materials used in the artwork. I don't like people treating their primary material like it was dogshit, unless of course, that's what you make with it. The bulk of my Ceramic friends felt the same way and if they did not mix it themselves, they had it mixed at Paoli. Those were big names like Soldner, Voulkas, Masterson. They evolved very differently.

Eben Horton 09-04-2020 10:34 AM

Just my observation over time but itís not the studio owners who Are that concerned by batch dust, itís the employees. They donít have much say in how a shop is built and are left holding the broom.

That said, about a year or 2 ago I switched to SP batchís small bag option and will never go back to the 50 lb bags again. It really eliminated just about all dust issues.

Pete VanderLaan 09-04-2020 10:38 AM

and get yourself some oiled sawdust from any janitors supply . It really works.

I load my furnaces with a ladle.

Art Freas 09-04-2020 10:58 AM

This is where it is different working for yourself and by yourself. What ever you personally believe is irrelevant when you are an employer. The regulatory folks have their view and their view isn't optional.


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