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Pete VanderLaan 02-02-2018 01:10 PM

The release can be measured in micrograms per hour and it goes up as the temperatures rise. Durk Valkema had some very convincing data on that over lead releases.

Ron Mynatt 02-03-2018 05:18 PM

So what is considered a high level of Borax. I was given a recipe with 2.3 % borax . Does anyone know what Spectrum's % is.What would be a good percent?

Pete VanderLaan 02-03-2018 05:41 PM

Spectrum 2.0 has no borax . It was the SP 87 clone knock off. Sys96 was indeed high borax but none was what you might consider excessive. It's really more a question of what can't molecularly combine in the glass. So, it gasses off.

Cristalica would not appear to have a high borax content based on the formulation but they way it hits furnaces suggests otherwise. If you count molecules, which is the mole theory of glass, it presents a very different picture. Your furnace is the witness. Borax attacks fireclays and silicates. It's the yellow stain. It's your furnace dissolving.

Eben Horton 02-03-2018 07:15 PM

I can remember big yellow cakes all around th doors of the furnaces at RIT from the cullet. We used Gabbert 4C cullet. Man I hated that glass.

Sam Stang 02-04-2018 02:03 PM

cullet shortage
It seems here in this discussion that the only alternatives to cullet are to make your own batch or buy spruce pine. I have been melting glasma 705 batch since about 2006 that I buy from Bill Glasner. My melt temp is 2175f and I have really nice glass with no cords. Much better than any other glass I have used, optically, in my opinion. Although it is more expensive, (88 cent per lb.) I feel that I am saving a lot of money over spruce pine batch due to the lower energy cost and greatly increased furnace/crucible life. It is a perfect fit with spruce pine 87 and spectrum 2.0. It also cuts and polishes beautifully. I am using a Hugh Jenkins recuperated burner system in a really old pre-hub style furnace that John Chiles and I built in 1993 with an ifb liner.

Pete VanderLaan 02-04-2018 02:11 PM

I think that's a nice glass but not for the inexperienced Sam. I have been told that it is a bit high on expansion by John Croucher but I've not measured it. I still think it would be very tough to melt in a wire furnace. It is brilliant stuff given the high barium content.

Sam Stang 02-04-2018 03:29 PM

It is no harder to melt than any other batch. It is just batch and maybe the inexperienced should stick with cullet? I don't really agree but that's ok. Get a decent respirator and a hepa filter vacuum and use both a lot.
And I don't have experience with anything other than gas furnaces.

Pete VanderLaan 02-04-2018 06:27 PM

I don't think the upcoming dominance battle is going to be about batch. It will be cullet. Somewhere around 2000 the glass community switched from a body that melted a lot of different things to one which never melted anything but cullet/ It went to wire melters and all of the prior approaches were sort of dumped.
Theres nothing wrong with GLASMA at all. It;s a beautiful glass but if over fired has issues. That' s hardly the problem these days.
If Bill wants to come on the board and hawk his product, that's fine. It's fine if Lewis does it as well. Tom pretty much never does. They probably all should stick their best foot forward. I don't have an agenda beyond dissemination of facts.

The issue is more like what the middle of the road shop is going to do as they realize that Cristalica is not solving the problem, cuz it won't.

Eben Horton 02-04-2018 06:41 PM

What is in Glasma 705 that helps it melt at such a low temp?

Scott Benefield 02-05-2018 06:32 AM

Hi Sam

What's your charging schedule like for the Glasma? I'm running a slightly different formula (702A) than the one that you get, but I'd be interested to compare. The instructions that I received from the UK supplier are:

Raise furnace from working temp (2017F) to 2282F
Top up crucible with batch, allow 30-40 minutes between charges
Maintain furnace at 2282F for five hours after last charge
Ramp down to working temperature, but allow 1.5-2 hours before working

I include a squeeze down to 1900F and work at a slightly hotter temperature (2050F), but otherwise it works pretty well. If you're loading at a colder temperature, are you raising it up for the fining part of the cycle? Or holder it longer at the lower temperature?


Sam Stang 02-05-2018 07:14 AM

Hi Scott,
I charge at a really low temp over the weekend. maybe 1920 or so. My burner is really under powered so heat recovery takes a while. Down to the mid 1800's after a few scoops each time. I have it full by Sunday night and leave it at a setting that will slowly climb up to 2000 by Monday morning and then I heat it up to 2175 (over 5 hours or so) and cook it for 3 hours at that temperature. My turndown is also a really slow curve due to the heat recuperation. I haven't carefully tracked it but it seems to be staying above 2100 for a couple more hours at least. So, the furnace is hot for a long time. Eventually squeezing just below 1900 by mid day Monday. Work at 1900 to 1950. I make a lot of murrini pieces gathering over very soft colors so I want it cold. I have a 2nd small furnace (hub mu800) with 2.0 cullet or color that I use on Mondays and charge it while blowing glasma or if it is not on, I can just make cane stuff or I work in my machine shop.
Btw, I am getting 3 years out of a crucible. About 150 lb pot.

Scott Benefield 02-05-2018 01:04 PM

Thanks, Sam, that's interesting to hear and that's a very impressive pot life. I'm in a situation where I often have to do overnight charges, so the higher temps allow me to go through the process more quickly. No second furnace to take up the slack, either.

Why is the proto-Hub furnace underpowered? Wasn't John using the Eclipse Thermjet burners back then?

Pete VanderLaan 02-05-2018 02:36 PM

Given that charge cycle, the pot should last quite a long while. It seems quite cold to me. I'm charging now and pretty much run it up to 2250F before I start. Keep in mind that all of these issues undergo quite a change when there's no flue and that is the case with most wire melters which in turn makes the glass formation a real issue.

Sam Stang 02-05-2018 06:28 PM

Hey Scott,
The electricity would go out a lot in my rural area so I wanted to run it without a blower. I used a Gib tip venturi for many years. I started melting it at 2225 and gradually dropped the temp bit by bit without noticing any decrease in glass quality.

Andreea Virag 02-14-2018 07:53 AM


Originally Posted by Pete VanderLaan (Post 138239)
Well, I talk to a lot of people, including distributors and manufacturers. This has been coming for some time and has to do with why I keep suggesting that the price has to go up. - a lot. Several suppliers are now out of Spectrum ( Really SP87 cullet) entirely which happened a little more quickly than anticipated. Olympic hoarded it and has the remaining supply. Phil went and raided Cristalica since he's not an idiot, getting Cristalia to violate its exclusivity agreement with Spruce Pine. Given Spruce Pine, that did not surprise me. I would have done something similar.

The only trouble with this scenario is that Dobern has a furnace that can't make enough cullet to supply America, let alone Europe. Dobern , last time I checked had no plans to change out furnace productivity even though they are in a giant building occupying a small corner of that place. What I have gleaned is that they plan to push the current furnace with no maintenance plans and that could well crater in a few years. They already had one unanticipaed shutdown two years back. Even so, it still comes up short five tons a day with demand. What do you suppose happens when demand vastly outstrips supply according to Keynes ?
Eveline and I have talked casually about starting a cullet supply. We looked at it a few years back and did all the math and figured out the supply chain across the pacific. Then, Spectrum resurfaced like Glenn Close in "Fatal Attraction". We bagged it and invested in bringing Cristalica to the US through Spruce Pine. I really tried on that one, got the exclusive and had a lot of difficulty with the melts coming clean. Coupling that with biz practices I could not cope with, I withdrew from that partnership with SP taking Eveline with me.
The Spruce Pine furnace had already failed spectacularly with apparently no desire to actually do it over right. That was too bad in my mind but it is what happened. There have been hiccups surrounding a restart but I think it would take a massive change in thinking and managing and a cash infusion of about 500K. I'm 67. I make my own glass. How do you get by? I don't need it certainly.

Now the line I'm seeing is one I have been concerned about for some time. I got news last night from one furnace maker that the Cristalica is eating the liners for his furnaces. I'm not surprised by that based on the borax/barium content of the goop. I offered Dobern a change in the formulation to affect the problem. They passed, which I expected. They have too much invested in Kuchinke and I get that. What I expect to hear next is that the pots are dissolving as well. The stuff is really very similar to Sys96 but has a higher expansion, around a 97. Sys96 was actually a 94.1.

If it was me as a small studio glass blower, , I'd suck it up and melt SP87 batch. Ever so much harder on the absolutely spoiled glassmakers of today. I currently know of no other startups even considering the issue. Oceanside next year is no answer. I don't particularly want to bring Eveline and the Shanghai group on right now although we have the capacity for raw glass now. . I'm tired of the way they get treated. In this community, China is viewed suspiciously. i know better. You get what you pay for. Just look at how many clear cullet makers have failed.

I may hold a class just based on making your own clear. I bet it would fill right up. Takers?

Hello Pete,
and hello to everyone,

As Pete knows me, but the others in the thread might not, I must mention that I work for Cristalica and handle the sales worldwide, so I can get some direct info about the current situation. 😊
What Pete explains about production capacity was absolutely true for that past period of time when he knew of our furnace directly.
At this point, I also want to thank him for introducing us to the US market and the vast array of clients we are now happy to supply, via either Spruce Pine, or Olympic Color Rods.
I want to give an update to that, i.e. that since Pete and us have spoken directly, the larger furnace in Germany has been fired up to meet demand. During the past year, in parallel with Spectrum not producing any more, we have noticed a higher demand and this being said, we want to also take the opportunity and inform you of an increased production capacity (which we will gradually keep raising) and a renewed guarantee that our capacities are planned long-term so as to ensure that our Premium product is accessible and available to all the artists we admire. As such, we want to ensure you our existing and possible future clients that we will meet the demand for glass without problems, as we have planned.
About the borax issue, as Pete mentioned, we have discussed this at that point in time. As in Europe and in other parts of the world, this issue has never arisen before, we are now again looking into what we can specifically do for clients encountering this problem. Please kindly forward any such photos, questions and description of this to our direct distributors, Olympic Color Rods and Spruce Pine, so we get word of any questions you may have and see further steps in this respect together with our partners on the US market.

We hope you do enjoy working with our cullet and look forward to seeing you all in la bella Italia, at the GAS Conference in Murano!

Glass is magic.
Andreea Virag

Pete VanderLaan 02-14-2018 09:55 AM

I sent you an email.

Durk Valkema 02-17-2018 03:37 AM

The volatilisation of boron introduced by the addition of Borax, from glass at temperatures of 1100 C and above is substantial due to its vapor pressure.
As an example in E-glass 10 25% boron loss is calculated, water vapor has significant impact on the evaporation of boron.
Boron volatiles condensate between 400 800 C and form all sorts of borates along the way playing havoc with alumna silicate refractory.

Pete VanderLaan 02-17-2018 07:03 AM

Thanks Durk. So I would imagine that 10 mole borax has a greater impact than five mole would?

Durk Valkema 02-17-2018 09:52 AM

The evaporation rates depend on the process conditions in the glass furnace, like:
Glass melt composition (at the surface);
Temperature of the glass melt surface;
Composition of the atmosphere. Especially the water vapor (air-fuel versus oxy- fuel) and the carbon monoxide contents just above the melt are important.
In furnace atmospheres with high water vapor mainly meta-boric acid is released.
Exposure time of a glass melt volume to the combustion atmosphere and
Local gas velocities and turbulence intensity just above the glass melt surface.
Electric melting has an advantage here but in a flue-less furnace the gathering port gets the full load.
In alkali melts, NaBO2 and KBO2 will evaporate.
In melts where CaF2 is added as flux boron seems to be released as OBF

Pete VanderLaan 02-17-2018 10:36 AM

The main destructive activity I see with it is in the gathering port or forehearth and the door. It makes a tar baby like material that has real staying power. Those furnace parts over here are largely insulating castables in the doors and some other 35% alumina refractories going up to 60%. But the silicates and fireclays certainly get consumed. I'm not seeing it in the crucibles- yet but the incorrect assumption that an electric unit did not need a flue was simply dead wrong using these materials. The little wire melters get it the worst. You just can't use any fluorine in electrics. It's either nitrate or lithium driven and lithium is pricey stuff. I did unsuccessfully try to get Dobern to get the stuff out of the glass 18 months ago but I was not surprised to see them pass on changing it. It seems to me right now that if Oceanside were to decide to make the purloined SP87 cullet in Tijuana that it would really cripple the popularity of the Cristalica which is a shotgun marriage right now. . The down side? They'd have to do it right. Life without borax would be better. I do wonder where the price will settle. No one is making any money at $1.00 lb.

Heather Hepp 02-22-2018 08:43 AM


Originally Posted by Pete VanderLaan (Post 138239)
I may hold a class just based on making your own clear. I bet it would fill right up. Takers?

I would take your class on making clear glass.

Jordan Kube 02-22-2018 04:21 PM


Originally Posted by Heather Hepp (Post 138631)
I would take your class on making clear glass.

Heather, I would get a copy of the 4th edition of Glass Notes. Pete wrote an excellent section in there about mixing your own glass. Next, the color making sub-forum here on Craftweb has some posts that are real gems of information. A little more time consuming is searching through the whole site for information but is also very rewarding. The glass notes thing is probably the closest thing there is to an instruction manual. Dave Bross has posted what looks to be a couple of nice clear formulas as a place to start. Expect to pay at least $3000 for the equipment and chemicals to get you started. I think I am paying $.55 a pound for the clear base I am using in the quantities I am buying in. Just as a spitball estimate I would add $.25 per pound in your labor to measure and mix.

Heather Hepp 02-22-2018 04:53 PM

Thanks, Jordan. Much obliged for the advice. I won't wait on Pete to have a class.
Are you melting your clear in that slick wire melter?

Pete VanderLaan 02-22-2018 05:34 PM

Indeed I have no rescue classes in my plans today. I don't find clear to be very hard. My costs on making it are higher than the ones Jordan cites but not all clears use the same stuff. I did lay out some very straight ahead 96 clears for Henry in Glassnotes IV but now the book itself has gotten quite pricey and it's not to say that I haven't moved to new places in the last ten years. 3K may be about right for the cap outlay, I suspect a bit less. Under a dollar a lb for clear is doable. Wire melters are not a good place to start.

Spruce Pine mixes my formula for me now- nice to the old man. I may go back to doing it myself but materials in rural areas is now an issue. I think the thing that discourages me the most in todays glass community is how frail the response is to being self starters. Dust, poisons, it can all be dealt with easily. At one time, we were adventurers, not so much now.

As Henry said "Glass is fragile". That's true. It's not guaranteed either.

Jordan Kube 02-22-2018 05:51 PM

I'm melting exclusively color in the wire melter although I'm not sure how slick it is. I have some improvements I'd like to make. Got me up and running pretty quick though.

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