Irid pitting - revisited

[Avery Anderson]

I agree with David on collectively to trying to get to the bottom of this problem. My entire body of work, that I have spent years developing, is based on using the irid side down. It is unnerving that I will have to worry about each piece "making it" through the various firings. Yet, it makes no sense that I haven’t encountered this problem ever before....and 16 years is a lot of firing irid side down!

I know Bullseye has spent much time and effort trying to analyze this problem, and while they found some sources - such as thin fire - that exacerbate the problem, it still isn't the defining answer.

I'm far from a chemist, (are their any chemical engineers on board?),but I wonder if there are different batches of Stannus Chloride or formulations. As I understand it, this coating is a mixture of stannus chloride, and various tin chlorides. If they were formulated a bit differently from batch to batch, would that affect the way these chemicals react to heat? When you coat your glass David, do you use exactly the same formulation each time? Same amounts of stannous chloride, tin chemicals? Same firing schedules? Same everything and yet still have the odd piece that pits?

Avery

[Phil Hoppes]

Avery,

Couldn't agree more but I think the "ball" so to speak is really in Bullseye's hands not ours. I mentioned an N-Factorial test rather toung in cheek but that is what Bullseye would need to do to really find the problem. Our "users" environment is too uncontrolled of an environment. The information we would need all lies in the BE factory. One would need to have traceability to the glass lot, chemicals, irid coating chemicals as you mentioned, kiln type, schedule, fiber/no fiber, wash....etc. It is a long list of variables. That is exactly what an N-Factorial experiment is used for. In any kind of manufacturing process you can determine the controlling variable for a variation in a process by using this kind of technique. It works quite well in fact but we don't have access to the most important pieces of info which happen to reside in the BE factory.

Phil

[PDXBarbara]

Avery,

Couldn't agree more but I think the "ball" so to speak is really in Bullseye's hands not ours.

Phil

Hi Phil...
But B.E. is just one of the courts in which this ball bounces. This thread alone indicates that pitting might occur with other manufacturers as well, plus home-made irid.

Although it seems unlikely, this could be an opportunity for the B.E., Uroboros, & Spectrum techies to work together to solve this unpredictable -- but common -- problem.

xxoo, PDXonolennonBarbara
"You may say I'm a dreamer, but I'm not the only one...."

[Rebecca M.]

I've been following this thread with great interest. In a few days when my maglesses are done, I'll be firing a blank of BE silver irid on black. Much of the silver will be etched off later, but if those pits happen......

I did something the other day which may or may not be related, but the results look somewhat the same only on a smaller scale. I was trying out an old watercolor effect of sprinkling salt on wet paint to disperse color. Only I was trying it with micas. A very small area was brushed with mica solution, and sprinkled with salt. I fired it face up and definite pitting resulted.

This may be a huge leap on my part, maybe to the other side of the moon, but I went looking for chemical compositions of sodium chloride, stannous chloride, which led me to others like sodium stannate and stannic oxide. On one site;
http://www.wm-blythe.co.uk/WMBLYTHE/CSD ... enDocument
#12 caught my attention for some reason. On another site it listed Incompatabilities for stannous chloride. Sodium, potassium, bromine triflouride, calcium carbonate, calcium acetylide, ethylene oxide and nitrates. It also said contact with strong oxidizing agents or alkalis (sodium chloride is listed as an alkali metal on the periodic table) will generate heat and fumes. So I was thinking that if any part of the chlorides were derived from sodium chloride (salt), that would create a problem right off the bat. So I guess even if there were no sodium chlorides in the composition, anything with sodium that came into contact with the irids would be a culprit.

I'm probably way off base, but I thought I'd throw it into the mix because of my salt experiment. The little grains that didn't desolve sunk in and pitted the glass. The ones that did desolve dispursed and gave the rest of the area a sunken matt look.

[Brock]

Avery,

Couldn't agree more but I think the "ball" so to speak is really in Bullseye's hands not ours. I mentioned an N-Factorial test rather toung in cheek but that is what Bullseye would need to do to really find the problem. Our "users" environment is too uncontrolled of an environment. The information we would need all lies in the BE factory. One would need to have traceability to the glass lot, chemicals, irid coating chemicals as you mentioned, kiln type, schedule, fiber/no fiber, wash....etc. It is a long list of variables. That is exactly what an N-Factorial experiment is used for. In any kind of manufacturing process you can determine the controlling variable for a variation in a process by using this kind of technique. It works quite well in fact but we don't have access to the most important pieces of info which happen to reside in the BE factory.

Phil

This sounds like a good project for Ted Sawyer @ BE R&E.
He knows everything. If you don't believe me, just ask him!
Brock

[Avery Anderson]

[quote="Becca"]I've been following this thread with great interest. In a few days when my maglesses are done, I'll be firing a blank of BE silver irid on black. Much of the silver will be etched off later, but if those pits happen......

Hi Becca.

Ron Coleman is the only person, to my knowledge, who has experienced pitting when the irid was fired surface up. In fact, the piece I recently had problems with had four inserts of the same irid (from the same sheet) fired on the top layer. Only the bottom layer pitted, so you probably won't experience this problem firing the silver irid face up.

I think your comments on the salt are interesting. I wish I was a chemist or knew more about this coating process.

Avery

[Paul Tarlow]

<snip>But B.E. is just one of the courts in which this ball bounces. This thread alone indicates that pitting might occur with other manufacturers as well, plus home-made irid.<snip>

I've changed the name of this thread to reflect the fact that this isn't limited to one manufacturer and to minimize risk that a casual observer might assume otherwise.

- Paul

[Brock]

I've changed the name of this thread to reflect the fact that this isn't limited to one manufacturer and to minimize risk that a casual observer might assume otherwise.

- Paul

Good one, Paul. Brock

[PDXBarbara]

<snip>But B.E. is just one of the courts in which this ball bounces. This thread alone indicates that pitting might occur with other manufacturers as well, plus home-made irid.<snip>

I've changed the name of this thread to reflect the fact that this isn't limited to one manufacturer and to minimize risk that a casual observer might assume otherwise.

- Paul

Anyone think there's a chance that the players could bounce this particular ball together?
BB

[Paul Tarlow]

Anyone think there's a chance that the players could bounce this particular ball together?
BB

That's a tough one.

The fact that BE made specific changes to fix the problem with their primer implies they have some specific ideas around cause. That puts them a step closer solving the problem and adding another product differentiator.

As much as I'd like to see collaboration, I can't fault a manufacturer for not wanting to share their intellectual property with competitors.

- Paul

[Brock]

Anyone think there's a chance that the players could bounce this particular ball together?
BB

That's a tough one.

The fact that BE made specific changes to fix the problem with their primer implies they have some specific ideas around cause. That puts them a step closer solving the problem and adding another product differentiator.

As much as I'd like to see collaboration, I can't fault a manufacturer for not wanting to share their intellectual property with competitors.

- Paul

. . . and to be fair to Bullseye, or any other manufacturer, they put a product out there in good faith. Then hundreds of us do hundreds of different things to that product. It's hardly surprising that some of those things produca a less than desirable effect. Brock

[PDXBarbara]

Anyone think there's a chance that the players could bounce this particular ball together?
BB

That's a tough one.

The fact that BE made specific changes to fix the problem with their primer implies they have some specific ideas around cause. That puts them a step closer solving the problem and adding another product differentiator.

As much as I'd like to see collaboration, I can't fault a manufacturer for not wanting to share their intellectual property with competitors.

- Paul

Ah, well, the Mysteries-That-Be know it ain't the first time I've been ridiculously naive...

BB

[PDXBarbara]

. . . and to be fair to Bullseye, or any other manufacturer, they put a product out there in good faith. Then hundreds of us do hundreds of different things to that product. It's hardly surprising that some of those things produca a less than desirable effect. Brock

Don't misunderstand, Brock, even tho I'm naive! I'm not trying to blame... I was dreamin' that knowledgable brains might work together to solve a common mystery for themselves and their customers. In other words, many of us bump into the irid-factor at one time or another.
Frankly, I'm surprised sometimes (given some of the things we do to glass) that it doesn't turn to powdered sugar for casual sprinkling on breakfast cereal or something....
xxoo,
BB
P.S. Hey, maybe someone'll roll in stannous chloride and fire themselves up for the calendar photo... Iridfinger (to the tune of Goldfinger).... still naive? Aw shucks.
BB

[Phil Hoppes]

Barbara,

You see if this was any other product like ....say software....especially from a certain company in Redmond you would call this a feature. In fact they would change their EULA (End User License Agreement) to reflect this and then want to charge you more for it!!!

Phil

[Tony Smith]

Don't misunderstand, Brock, even tho I'm naive! I'm not trying to blame... I was dreamin' that knowledgable brains might work together to solve a common mystery for themselves and their customers. In other words, many of us bump into the irid-factor at one time or another.

This is one of the reasons I love doing research in the non-profit world of government funded research. It's one of the few environments where there is truly cooperative development and an open sharing of technology and ideas... not that it's always that way... okay, maybe I'm dreaming too

Tony

[PDXBarbara]

Barbara,

You see if this was any other product like ....say software....especially from a certain company in Redmond you would call this a feature. In fact they would change their EULA (End User License Agreement) to reflect this and then want to charge you more for it!!!

Phil

EULA... like the sound of that... good name for a licensed doll... real loud now, let's whisper "EULA SIR MICK...EULA, I SAY!" Boy, Phil, I'm gonna have EULA rattling around in my skull all day... EULA. A rallying cry.... EULA... (ok, I'll stop now...)
xxoo,
PDXEula

[David Williams]

Lani has shared some irridizing tips with me in the past even after we had all those many arguments. To her credit. But I'd still be disapointed if they were holding proprietary information that could be relevant to food safety. Disapointed but not surprised. I do know Spectrum is going to start doing a tin irridized product.

Avery, Bullseye and Uroboros are far more sophisticated than I am in irridizing. All I can make is rainbow irrid. I can't make say, a whole sheet of silver or blue. I know that there are othe metal salts that people add to the stannous mixture to get those colors. Ferric chloride, strontium nitrate are ones listed in Lundstrom. Those aren't really secrets. But I don't use those. Also there are of course many variables in the coating process. Lani Once told me they had been doing it for many years and still produced off sample sheets (not related to this problem I assume) on a regular basis. For one thing, the solution seems to have a very short shelf life. The other thing is, you're talking about a very thin layer of material. I'm sure bullseye has a way to do that very consistently but for me, I just open the door and make a few passes over it with the gun. It makes a huge difference what temp, what psi I have the compressor at, how I have the gun set up, how far away I stand etc etc etc. So It really is hit and miss. I've gotten sheets that are far better than anything I've seen from the factory, that rival dicro. Conversely I get alot of crap too which I just use for the backs of pieces. So I guess the answer is yes I try to do it consistently but no I don't.

I do think the most likely theory is that the problem is a result of some irregularity in the coating process or formulation. Like, maybe undissolved bits of tin, or some impurities. But you'd have to delve way further than that to figure out the whole story. Like why it happens mostly on the thinner parts of the coating, why it happens when inverted, etc

[Avery Anderson]

David:

Thanks for sharing and for your insight. I'm guessing we'll not reach a real conclusion or answer because of the variables you have mentioned, sigh. This is difficult as I'm not happy about unpredictable results. I'm resigning myself to just keeping accurate notes on every firing using irid down with the hope of finding some common denominator. Although, not knowing the base information, as Phil discussed, may make this a meaningless task. I do appreciate the information Mary Kay has shared as this certainly gives me a good starting point on some of the major causes of this phenomenon.

Avery

[Paul Tarlow]

Barbara,

You see if this was any other product like ....say software....especially from a certain company in Redmond you would call this a feature. In fact they would change their EULA (End User License Agreement) to reflect this and then want to charge you more for it!!!

Phil

Boy, talk about opening a can of worms. Can't we talk about something less controversial...like religion.

[Phil Hoppes]

Oh come on Paul......Uncle Billy is our friend. He's only looking out for our best interest....and our wallets....and our bank accounts.....and our privacy.....and well you get the picture.

Phil

PS - To Mr. Gates's credit, he is probably more Philanthropic than anyone else of his stature and for that I do give him lots and lots of credit. He's just so darn much fun to pick on thats all