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  #51  
Old 12-07-2003, 08:40 AM
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Pete VanderLaan Pete VanderLaan is offline
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David: Do you use color or don't you? If you do, it was made in an inefficient furnace 4-10,000 miles away and sells for up to 55 dollars a KG. Thta's inefficiency.

I make five gather pieces a lot. If I were to use a 100 lb melter I would charge every day or every other day, and at 2150 if would take forever to fine out. The cost of running a furnace is during the charging time, not the idling time. My electric bill would probably actually be higher than it is with the current moly unit, based on high fires.

Further, pot life is based on the same cycles. Your pot is good for 70-90 cycles and should be replaced, invested or not if you want great glass quality. At my current usage I would pull the pot every two months. That is not attractive.

What works for you is due to your scale of operation, not the genius of the design.
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  #52  
Old 12-07-2003, 10:38 AM
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OK OK!

You guys have almost convinced me to retrofit my wire melter with moly.

So where do you get specs and prices on moly elements?
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  #53  
Old 12-07-2003, 12:51 PM
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I suspect that the way Matt Bezark did his would be similar to your sizing. Steve Stadleman consults on design and also builds the systems. I flew to Portland when I wanted to build one of these things and Steve and Jon Meyers were aces. Steve is the one that showed Kyle Gribskov and Jon how to build these. He walked Matt thru his on the phone. He also was key to Henry Halem in his venture. I flew steve to New Mexico when I was ready to asemble the electrical components of my big boned beauty. He knows where to find all the weird parts, all the cheap parts, and most importantly how and why they work. I cannot recommend anyone as highly as I would Steve. He really knows his stuff. Also he's getting to be too old to remain a fireman.
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  #54  
Old 12-08-2003, 01:36 AM
Parker Stafford Parker Stafford is offline
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I tend to feel that how your furnace is set up will determine how well it performs. How close are the elements to the glass line? Are they above or below the pot? How well are the elements protected if they are below? Watt loading is important. How much dust they will get on them, or popping cullet is a concern and a consideration. Being able to use your eyes and powers of observation are important in a wire melter. Learning to see a dying element a month before it happens is not hard to develop as I do it all the time. Every now and again, something will come along that will f--- it all up, like a long power outage, or bad metal in the wire. I believe this has happened once in the seven years I have had this furnace.

I think that preheating batch is okay if you can also keep the batch wet, which gets to be tricky when you go up to around 900 degrees or so. I used to preheat, and it did help with speeding up the melt, but since my elements are above the pot, I was getting dusting, and this was not good for the elements. No free lunch. You gain in one area, lose in another. I am not about to step into the sweet smelling mess that is the moly/wire debate. Do what works for you in your situation. When it no longer works, cast about for something new. The bottom line is that you enjoy it and are able to make good work. If any of those is off, something needs fixing. If your furnace is giving you trouble, maybe it is design related, maybe it is time for something new.

You can melt batch pretty cool, but you need more time. You can also melt it hotter, but you might lose a little on wire life. Take your pick. I know a guy who never turns his wire unit up to charge temp. He owns a flat glass business and 80% of his business is doing large plate for restaurants, custom installs, etc., so he can charge after using up a pot, then come back to it a number of days later. Says if he has enough time, the glass is perfect. He also gets real good element life.

I find that the best squeeze comes from a drop to 1900 degrees IN MY UNIT. If I do a drop to 2000, I need an extra day for it so sit (again, in my unit)in order to get paperweight quality glass (the bar is lower for some blown things), and have done it like this when I went off for the day knowing I would not be blowing.

Electric will always tend to be more bubbly in my opinion as a result of the atmosphere. It is regular earth atmosphere, not a mix of hydrocarbons being combusted. So take that into consideration Actually, batch is ALL I melt, and I do the melt starting at 2280. I go up to that, and I charge about 50 lbs at first in a 130# capacity crucible. No preheating the batch, and no strict adherence to a 30# only charge size. Then I drop the temp down to 2220 and do the middle charges at that temp. Then before I do the last charge, I ramp back up to 2260-80 and let it soak there for about 4-7 hours (after the charge), although I might go longer if I have the time. If I had more time I might keep the temp down around 2230-50. I keep my high temps in short duration, but I believe in them for getting gasses to expand for fining. I like to have a six hour squeeze before turning up to work temp. If your unit takes a while to drop in temp, like mine does, you need to take that into consideration for the tail end of your "melt" which is your squeeze. Early on I realized that it took my furnace about 5 hours to drop from charge temp to squeeze temps., and when I adjusted the melt to take that into consideration (for the time actually spent at around 1900 F.), the glass quality got much better. I was going in the evening to turn the furnace down, and often it was late enough that the unit did not have enough time to get a good squeeze in before the a.m..

How careful I am about the melt depends on what I am making. If I am doing solid, I am very anal about how I do the melt. I also stir the glass with a spud as it is the most convenient way to mix the glass in my opinion and get very good evenly mixed glass of top quality. I once saw a guy mixing his melt using a punty attached to a drill. I tried this, and found it to be a big pain in the ass (this was a big studio). It actually got more bubbles in while not really mixing as well as I would have liked. Do the mix at a high temp so you get some real life agitation. I am talking in the 2220+ range. Hotter the better, in my humble opinion, as the glass mixes so much more readily. The glass comes out much better, even when you have a crucible in good shape. When the crucible is in bad shape, you are kind of trying to make a purse from a sow's ear. Sometimes it can work.

Parker S.
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  #55  
Old 12-08-2003, 10:16 AM
David Paterson
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Thanks to Parker and everybody else who took the time to reply to my questions.

-David Paterson
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  #56  
Old 12-08-2003, 11:30 AM
David Williams
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Quote:
Originally posted by Richard Huntrods
Geez - you molly minders just won't quit, will you? I get less flack from the gas melters.

Sometimes wire is the ONLY way to go.

1. Wire is boatloads of money cheaper to build. Also way simpler (no huge transformers and all that other stuff)
2. Wire furnaces take up way less space than molly rigs. For very small shops, a wire furnace may be all that will fit.
3. For the "weekend warrior" glassblower, I cannot see any scenario short of winning a lottery where Molly would make more sense than wire.

Besides, This is a "wire furnace" thread. We don't got no molly religion here!

Cheers,

-R
Hiya Richard, I think the reason moly comes up in these threads isn't because anyone is trying to sell you, its just the far better and believe it or not, cheaper way to go. I know its hard to hear that because the allure of getting a studio up on the cheap is so strong. Believe me I know. No one could steer me away from building a wire furnace, I had to find out for myself. But if you're a smart cookie you'll listen, and save your money and build a moly. I wish I had made that decision before I built my wire furnace. Its really not so much more expensive. All the refractories have to be purchased anyway, and the controller. The extra money is in the electronics--the transformer and scr. The elements cost a bit more in the short term, but averaged over the life of your furnace the cost of moly elements will be FAR less. Plus, if you are a weekend warrior the moly elements can handle frequent cycling up and down where wire won't. Hey buddy I'm just saying it to help you out, take it or leave it.
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  #57  
Old 12-08-2003, 04:06 PM
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Hmmm.

What do you mean by SCR? Do you mean a straight "digital relay" or something more exotic?

Also, what type of transformer is required - can you give me a rough idea of the current and the primary and secondary voltages? I realize there's a whack of design involved, but I'm just looking ballpark (i.e. 20-50 amps 240V primary xxxV secondary is quite different than say a Neon transformer).

How do people normally place the moly elements, and how many are normally used? Again, I know this is part of the design, but are we talking 2 elements, 4 or 6 for a small (< 100lbs) furnace?

Finally, is there a standard size moly element?

The thing is, this furnace is already built. I'm using digital relays + a Watlow controller. The furnace has a 1 cu ft. heating chamber, 40lb crucible. Would molly even fit in this little puppy, or are we talking a whole new furnace?

Thanks,

-R
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  #58  
Old 12-08-2003, 04:08 PM
David Paterson
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David,

Where did you buy your moly elements?

Thanks in advance.
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  #59  
Old 12-08-2003, 04:47 PM
David Williams
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Quote:
Originally posted by Richard Huntrods
Hmmm.

What do you mean by SCR? Do you mean a straight "digital relay" or something more exotic?

Also, what type of transformer is required - can you give me a rough idea of the current and the primary and secondary voltages? I realize there's a whack of design involved, but I'm just looking ballpark (i.e. 20-50 amps 240V primary xxxV secondary is quite different than say a Neon transformer).

How do people normally place the moly elements, and how many are normally used? Again, I know this is part of the design, but are we talking 2 elements, 4 or 6 for a small (< 100lbs) furnace?

Finally, is there a standard size moly element?

The thing is, this furnace is already built. I'm using digital relays + a Watlow controller. The furnace has a 1 cu ft. heating chamber, 40lb crucible. Would molly even fit in this little puppy, or are we talking a whole new furnace?

Thanks,

-R
No one should mistake me for a moly expert. SCR stands for silicon controlled rectifier which is a fairly common piece of electronics. What you should do is search the archives where there is tons of info on this. Study up, and come back and ask Steve what you need to know.
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  #60  
Old 12-08-2003, 05:13 PM
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you can learn it on your own but I think you are better off hiring Steve as a consultant. There's a peculiar stage where people want to get something for nothing and I suppose it's human nature. It happens with me and people calling about glass chemistry all of the time.

I had finally matured enough when I needed to know about Moly's that I just bit the bullet and bought the plane tickets to Oregon. That was a risk. By the time I was paying to fly Steve to New Mexico, it wasn't a risk at all anymore.Before that, I had been promised a reasonable moly system for over a year by someone else. Push came to shove and they couldn't/wouldn't deliver. That furnace that Steve showed me how to wire would have involved my making tons of critical mistakes, and the acquired knowledge will be with me for a lifetime. I do the same thing with the color. If people really want to know how to do it, they pay me 1500 bucks and spend the work week with me being overwhelmed. Steve is paying me to take that course in three weeks.
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  #61  
Old 12-08-2003, 05:58 PM
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But, I don't think its all that much more complicated than wiring your average control system with a relay and a safety circuit. I think with some experience building control systems and a bit of help from experts like Steve it is easily doable on your own. Easier if you can fly in your expert. The theoretical part is harder. Understanding the interplay between the scr and the transformer has always been difficult for me, and I let that fear rule out a moly furnace for a long time. But Steves lecture notes made it a bit easier, along with the realization that I don't need to understand every last theoretical detail of how it works to feel comfortable with it in my studio. I think I had that epiphany when I was up at Bills who is a great gadget guy and inventor, and I asked him some esoteric question about the moly and he just shrugged his shoulders. I figured if he could live with that, I could too.

Ps. Take it all with a grain of salt, I may be eating my words. I'm going to pick up my moly furnace castings etc in Portland over the holidays and start building it when I get back. Meantime I'm still nursing the wire. Which by the way should be for sale in the spring.
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  #62  
Old 12-08-2003, 10:13 PM
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Of all the proponents of moly, no one has yet posted even one supplier, or a website that gives technical details about how they work, or other specifications such as size, configuration, cost, etc.

I know there is a degree of complexity to them, but basic information is necessary to even make a decision that you would like to use them for a particular application.

I also dont believe that it is rocket science, just more complicated than most other electrical configurations that most of us work with.

If george bush can run the country, surely all of us on this board can understand at least the basics of the design that these things require.
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  #63  
Old 12-09-2003, 12:21 AM
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David Williams,

Thank you for answering the question about SCR. That's what I thought it was, but I wanted to be sure.

David Patterson,

I agree with you 100%. I'm just looking for information myself.


-Richard
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  #64  
Old 12-09-2003, 12:28 AM
Steve Stadelman Steve Stadelman is offline
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Use the search engine on this site, I have written lots of stuff in the past that details all of this stuff. As to suppliers, I am importing moly's, Or I squared R makes them domestically or Kanthal corp.

Check the archives.

P.S. my favorite supplier of electrical components is Watlow. Excellent customer support and technical assistance.

Last edited by Steve Stadelman; 12-09-2003 at 01:22 AM.
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  #65  
Old 12-09-2003, 02:24 AM
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Some of you guys with wire and thinking to upgrade might also consider the path I took. What I did was, to get more life out of my wire elements I got a phase angle scr with a current limit which allowed me to dial down the watt loading on the wire, but also will be rquired for my moly system. I forget what I got it for but its in the archives because I remember talking about it. I think it was like 500$. It was from TTI global which I get all my control stuff from because I have a good relationship with them and they have great support and prices. Well it turned out after that we found out actually a zero burst crossing whozit scr was better for wire. But, to my untrained electrical mind it seems like the current limit is really the key to reducing the watt loading. In fact, I think if you got just a controller with percentage-wise output control (pxr3 129$) and cut down the output signal to an ssr you'd do just as well (with wire) but thats another thread. Anyway The phase angle scr is good for both systems and serves as sort of a bridge to the moly. As far as David Patterson what you asked about suppliers, schematics, etc. Its a relatively new method for melting in the studio and you have to sniff around to educate yourself. I think you'll find most of what you'll need to know in the archives here. I can't imagine that you'd find any richer single source of information for non-engineers outside of Steve's skull.
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  #66  
Old 12-09-2003, 05:23 AM
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Quote:
Originally posted by David Paterson
Of all the proponents of moly, no one has yet posted even one supplier, or a website that gives technical details about how they work, or other specifications such as size, configuration, cost, etc.

I know there is a degree of complexity to them, but basic information is necessary to even make a decision that you would like to use them for a particular application.

I also dont believe that it is rocket science, just more complicated than most other electrical configurations that most of us work with.

If george bush can run the country, surely all of us on this board can understand at least the basics of the design that these things require.
I put up a molly link to a mag article

I diddent understand it I hate all this elecrtical chat

But the link was well recived by those that know

Was pos about 3 - 5 weeks ago

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  #67  
Old 12-09-2003, 07:03 AM
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[quote]Originally posted by David Paterson
[b]Of all the proponents of moly, no one has yet posted even one supplier, or a website that gives technical details about how they work, or other specifications such as size, configuration, cost, etc.

That is simply totally untrue. This site probably has more nuts and bolts information about suppliers, theory and operation than anywhere I have seen. I suggest that you next say that this site has never posted any information about suppliers for color glass making. Use the archives.
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  #68  
Old 12-09-2003, 12:45 PM
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Pete and Steve are correct.

The archives topics don't always tell the whole story, but there's some great info in them if you just read through the threads.

Steve referred me to the archives, and I looked. There were two web references in those posts that summarize the info on Moly very well:

http://www.theglazine.com/features/molybdenum.html

for a good overall article, and

http://www.chromalox.com/

For total information on the control systems.

This manual answered all my questions on SCRs and power requirements for Moly:

http://www.chromalox.com/manuals/trainingmanuals/

Excellent stuff in those archives (and in the web sites they pointed me to)

I must admit, Moly sounds pretty fantastic. Expensive, but fantastic.

But... I still gotta fix my wire furnace and melt me some Spruce Pine batch! (just getting back on the thread topic, there...)

-Richard
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  #69  
Old 12-09-2003, 03:00 PM
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There is also a photo thread I took in Portland in "photos of studio stuff" called "to hell with the portland vase.
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  #70  
Old 12-09-2003, 04:25 PM
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Richard,

Thanks very much. I didnt search the archives because I follow this board quite closely and didnt recall the thread.

I agree that moly seems fantastic in many ways. A quick search on the internet for molybdenum elements from china turned up two sources that would obviously be cheaper than US based products.

When I designed my wire melter a year ago, I looked into both moly and silicon carbide enough to realize that they were too complicated design wise for my purposes. Also expensive in that I wasnt aware of the China option.

I agree with Pete that everyone's situation is different. I dont presently melt my own color, although I used to melt a few pots of color in a small wire melter. Now, I design a lot of my work to minimize the intensive use of color, and show the brilliance of the clear glass. I also use a lot of lustres and metallics on my work, which are surprisingly cheap.

One thing I think that most people dont pay enough attention to is the energy consumption of their furnaces, in at least some cases that I am personally familiar with. A friend of mine, a woman, bought a Correll pot furnace, because she "didnt want to be a furnace builder", even though she had seen me build two invested pot furnaces (typically, they take 2 days of work). Now she works a few extra weeks a year doing production work, compared to me, just to pay the extra costs. I usually go to the Carribean with the money I save for the same length of time. And she never uses the theoretically better glass quality that is available in her $20,000 Can dollar setup.
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  #71  
Old 12-09-2003, 09:29 PM
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Quote:
Originally posted by Pete VanderLaan
No one who blows glass should claim that they are "greener" than someone else.
i just found out that for $250 more per month i can run my furnace and annealers on %100 wind sourced electricity. how about that!!

matt.
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  #72  
Old 12-10-2003, 12:18 AM
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Just imagine if you could catch a small amount of the wind that this discussion board occassionally generates!
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  #73  
Old 01-11-2004, 05:49 PM
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David,

OK - I'm now melting Spruce Pine batch in my wire furnace.

I ramped the furnace up to 2150 at 100F/hour (with a couple of hours wait at 900, 1000 and 1100 due to the quartz inversion).

Once the crucible was at 2150, I started ladelling in the batch - about 15-20% of the crucible volume at a time. I let each fill start melting down for about 2 hours before adding more.

I'm currently sitting at about 1/2 full on my 40lb. crucible. (4pm, 1/11/2004)

Reading prior posts, Dave Bross melts homemade batch (if I read Dave's posts correctly) in his wire furnace. He fills at 2050 and then cooks at 2250.

Likewise, I'm going to cook at 2250. I just haven't decided whether or not to fill the crucible full at 2150 first, or start cooking when it's half full.

(remembrances of my first disaster with a full crucible).

-Richard
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  #74  
Old 01-11-2004, 06:59 PM
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Get it full at the lower temp. and then cook it at the higher temp.

You can add more batch as soon as the stuff you added before has gone flat, and is looking sort of like foam. You don't want to pile cold batch on top of unmelted batch. It's also a good idea to let the furnace recover temp. before adding more batch. That all happens about the same time in mine but that may be different in another melter.

You will be making a number of smaller batch additions at the end to get it up close to the rim.

The idea behind charging at a lower temp and then upping the temp to cook it is so that all the sand is dissolved and not making more bubbles for you to deal with while you're cooking it at the higher temp. As long as sand is dissolving there will be bubbles forming.
The fining agents like antimony decompose and produce gasses at the higher temp which cause the bubbles to swell and rise much more quickly than they would otherwise. The antimony also helps by sucking the really tiny bubbles back into solution in the glass as the glass cools on the squeeze below the point where the antimony changes valence around 2150F.

You may need to batch at a higher temp. with Spruce Pine. I've never used it so I don't really know, but I know it's made with fine mesh silica so I suspect it will do just fine at the temps. suggested. If you get silica snots and stones in the finished glass you'll need to batch at a higher temp.


I looked up Frank Woolley's comments on all this in "glass Technology for the Studio", which you can get from Whitehouse books for about $12. He says as long as you are batching at least 50 degrees below the temp. where you will be cooking you're OK. Frank was a Corning Glass engineer who wrote that little book to help studio glass artists.
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  #75  
Old 01-11-2004, 07:09 PM
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Quote:
Originally posted by Dave Bross
Get it full at the lower temp. and then cook it at the higher temp.

You can add more batch as soon as the stuff you added before has gone flat, and is looking sort of like foam.
Excellent dexcription! That's exactly what I'm seeing right now. I've added 3 rounds of batch so far, and the crucible is just over 1/2 full of "flat foam". I just added another run of batch, so it's sitting at 3/4 full - mixed batch and foam (as of this minute). Still all at 2150F

Quote:
You don't want to pile cold batch on top of unmelted batch. It's also a good idea to let the furnace recover temp. before adding more batch. That all happens about the same time in mine but that may be different in another melter.
Again, that's what I've been doing. My furnace drops from 2150 to between 2132 and 2140 during additions (I also keep looking )

It seems to take about 5-10 minutes to recover the temp, and I've been waiting 1.5 to 2 hours between additions (no reason, it just works out that way).

Quote:
You will be making a number of smaller batch additions at the end to get it up close to the rim.

The idea behind charging at a lower temp and then upping the temp to cook it is so that all the sand is dissolved and not making more bubbles for you to deal with while you're cooking it at the higher temp. As long as sand is dissolving there will be bubbles forming.
Sounds good.

Quote:
The fining agents like antimony decompose and produce gasses at the higher temp which cause the bubbles to swell and rise much more quickly than they would otherwise. The antimony also helps by sucking the really tiny bubbles back into solution in the glass as the glass cools on the squeeze below the point where the antimony changes valence around 2150F.

You may need to batch at a higher temp. with Spruce Pine. I've never used it so I don't really know, but I know it's made with fine mesh silica so I suspect it will do just fine at the temps. suggested. If you get silica snots and stones in the finished glass you'll need to batch at a higher temp.
Again, sounds good. I'll be anxious to see what this glass looks like when done. I know from SP cullet that this furnace will produce a very nice glass with a 1900 squeeze and 2150 working temp.

This time I'm going to play with working temp a bit - see what 2050 is like and all that.

Another question (If you've ever done this). If I finish charging later tonight, what about letting it sit at 2150 (charging temp) overnight, and then cooking it tomorrow?

Quote:
I looked up Frank Woolley's comments on all this in "glass Technology for the Studio", which you can get from Whitehouse books for about $12. He says as long as you are batching at least 50 degrees below the temp. where you will be cooking you're OK. Frank was a Corning Glass engineer who wrote that little book to help studio glass artists.
Thanks,

-RIchard
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