Irid pitting - revisited

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Paul Tarlow
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Joined: Sun Mar 09, 2003 4:06 pm
Location: Helios Kiln Glass Studio - Austin
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Post by Paul Tarlow »

Phil Hoppes wrote: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 :twisted:
Nah, he's just looking out for his stockholders. But then again, that is his job.

You're right about the philanthropic part. Most people don't realize that he has already spent more than half his wealth on educational and children's health related charity. Something I read recently observed that he has given away in wealth more than the total of the next top 9 philanthropists in the U.S. put together.
Lani McGregor
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Location: Portland, OR
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Post by Lani McGregor »

david williams wrote: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.
David, I can GUARANTEE you that Bullseye is not withholding any information that would be relevant to food safety. We had our irids tested in independent labs many years ago to re-confirm what we really already new: an tin irid coating (which ours is) is food safe.

I'm sorry that it wouldn't surprise you if we poisoned our customers.

Lani
Cynthia

Post by Cynthia »

Avery Anderson wrote: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
You can add me to the Ron Coleman category. I have had irid pit when fired up...but it was after multiple firings and it only happened once.

I should ammend this previous comment. The glass was an iridized transparent red, Cranberry Pink? and on inspecting the unfired scraps of glass from the same sheet, parts of the glass and coating, were slightly sketchy and bubbled to start.

My experience with this has been that I have more occurances of pitting when fired irid down on thinfire than on a primed shelf, and that it's only occured once when the piece was never fired irid side to shelf...

My solution is to fire on a primed shelf (unless I just have to have that irid fired on paper look), knowing I'm taking my chances when firing irid face down...but this demon rears it's ugly head only once in a while. Not that this makes it an acceptable occurance, just one I know will happen on occasion.
Last edited by Cynthia on Thu Jan 08, 2004 5:55 pm, edited 2 times in total.
Ron Coleman
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Location: Columbus, Ohio USA

Post by Ron Coleman »

Cynthia wrote:
Avery Anderson wrote: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
You can add me to the Ron Coleman category. I have had irid pit when fired up...but it was after multiple firings and it only happened once.
Let me set the record straight. My irid only pitted when it was fired down against the shelf, but that was after it was fired up first.

Ron
Don Burt
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Post by Don Burt »

Cynthia wrote: clip
You can add me to the Ron Coleman category.
I've never fused irrid, but add me to that category too, whatever it is. - Madam Bovary Boy
PDXBarbara
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Joined: Sun Mar 09, 2003 4:09 pm
Location: Portland, OR

Post by PDXBarbara »

Re: pitted piece I referred to earlier in this thread.........
PDXBarbara (Bader) wrote: However, you can check out that thread at:
http://www.warmglass.com/phpBB/viewtopi ... highlight=

You can see pix of my glass with the problem at:
http://www.pbase.com/pdxbarbara/crystal ... ystery_pix
PDXFebruary
well it's in the oven now.. after irid's blasted off. We shall see..........
ommmmm.
BB
Barbara Bader
David Williams

Post by David Williams »

I'm sorry that it wouldn't surprise you if we poisoned our customers.

Lani[/quote]

Hey Hey! Here we are just like old to times, eh? No I didn't mean it that way Lani my dear. I meant that if you had some proprietary information that could help ME not poison MY customers, it'd be great if you'd spill it-- but since it might also help the competiton it wouldn't surprise me if you didn't. Do you have an idea what causes this problem? I inferred from Mary Kays reference to changing formulas that you might have a clue.
Tim Swann
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Joined: Mon Mar 10, 2003 9:47 pm
Location: San Diego, CA

Post by Tim Swann »

I have been doing some research into the issue of pitting when iridized glass is fused with the iridized surface down. I have found information on the stannous chloride (and other salts) and glass reactions in several of the glass chemistry books that I have. None of the books and other documents gives the exact answer, so I am formulating my own theory. I would love to chat with a chemist if there is one that wants to get into the very technical side of this issue.

Tim
PDXBarbara
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Joined: Sun Mar 09, 2003 4:09 pm
Location: Portland, OR

Post by PDXBarbara »

PDXBarbara (Bader) wrote:
well it's in the oven now.. after irid's blasted off. We shall see..........
ommmmm.
BB
Pix at http://www.pbase.com/pdxbarbara/whats_new . (Click on "pitted Cosmos.)

Took the flattened piece up to 1500, short soak. Fired with the pitted side up on fiber paper (not Thinfire). Nice & smooth to the touch, but there's scum or devit where the pitting originally occured, & a sort of blurry look in those areas as well.

BB
Last edited by PDXBarbara on Sun Jan 11, 2004 11:52 am, edited 2 times in total.
Barbara Bader
PDXBarbara
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Joined: Sun Mar 09, 2003 4:09 pm
Location: Portland, OR

Post by PDXBarbara »

As I was packing up some paperwork while moving out of my old studio, I came across an article I'd printed out at some point. It's called:
" A Practical Guide to Iridizing Glass" by Arthur Allison. My disclaimer... I don't know anything about Arthur Allison, but maybe one of ya'll do... I neglected to make note from whence I downloaded this informal article.
Here's some quotes:
...."However, to create the iridescence consistently, and to make the best possible colors, four variables must be considered, and understood. 1) Base Glass; 2) Surface Glass; 3) Furnace atmospheres, and 4) Iridizing Spray.
"BASE GLASS
--snip--
"A base glass that is very oxidizing in nature, ie: one that contains a lot of sodium nitrate, potassium nitrate, arsenic, or potassium dichromate, can sometimes behave strangely. I call these 'silver suckers.' These glasses can sometimes literally eat the decoration off their own surface. You have a great looking piece when it goes in the box, but the next mrning it looks like you forgot to finish it...."

For what it's worth, guys.
xxoo
BB
Barbara Bader
Brock
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Joined: Mon Mar 10, 2003 1:32 pm
Location: Vancouver, B.C.

Post by Brock »

" A Practical Guide to Iridizing Glass" by Arthur Allison. My disclaimer... I don't know anything about Arthur Allison, but maybe one of ya'll do...

He's a glass blower, Ive seen him post on Hand Made Glass and CraftWeb
PDXBarbara
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Location: Portland, OR

Post by PDXBarbara »

Thanks for the info, Brock..
BB
Barbara Bader
charlie
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Joined: Mon Mar 10, 2003 3:08 pm

Post by charlie »

Phil Hoppes wrote:Point taken but something I belive is producing some kind of gas that is causing the openings, either that or the glass is being disolved some how and I don't believe that is going on.

Phil
maybe because it's thinner, it's creating a semi-permeable membrane and allowing migrating of water vapor after production? how about trapping some of the iridizing fluid under it during production, like flux under stained glass copper foil sometimes come out quite a while after finishing a panel?
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