Crystal irid

PDXBarbara · Post by **PDXBarbara** » Sun Aug 10, 2003 3:37 am

Got some crystalization on irid. Slumping on kilnwashed (BE wash) SS plate. BE 1116 (turquoise blue) irid down tried to scrub it off (scotchbrite kinda thing, gently w/ wire brush. Actually took off some of the irid. Never seen this before. Usually the irid down helps with the release. Plus the crystalization is specific to one innocuous portion. Ideas on what caused this?
PDXBarbara

Tom White · Post by **Tom White** » Sun Aug 10, 2003 11:41 am

Barbara, does the location and shape of the problem area have any relation to the size and shape of anything slumped on this mold in the past? Different glasses seem to affect kilnwash differently. Some seem to leave more flux in the kilnwash than others as seen by the discoloration of the kilnwash. I know this is more often a problem at fuse temps than slump temps but it is still a possibility here.

Best wishes,
Tom in Texas

PDXBarbara · Post by **PDXBarbara** » Sun Aug 10, 2003 1:30 pm

Tom White wrote:Barbara, does the location and shape of the problem area have any relation to the size and shape of anything slumped on this mold in the past? Different glasses seem to affect kilnwash differently. Some seem to leave more flux in the kilnwash than others as seen by the discoloration of the kilnwash. I know this is more often a problem at fuse temps than slump temps but it is still a possibility here.

Best wishes,
Tom in Texas

Hi Tom. First time slumped on this side of the SS mold. I've used the "normal" side before with fine results. The flip side has a more extreme shape. It was freshly washed (BE wash). Because of the strange shape, I got worried about the SS squeezing the glass upon cooling... so at about 650 F. I shoved the glass askew on the mold so it couldn't catch up in a crevices (about 1/4 inch deep, or so). That was successful.

Oh yeah... while supervise the slump, I added both time & temp. I'd programmed in a burst of heat to get it up to 1300 for a quick polish on some bits I'd sanded & ground. added on about 20 degrees... and kept checking it every 3 -5 minutes...(which kept it from reading too hot, but also kept the elements on than if I'd kept the dang lid shut.) So it hovered around 1300 for about mmmm 15 minutes. polished well... but this irid-on-the-bottom screwup was unexpected.

I'll try plopping the problem area on the scanner ... if it works, you'll see what I mean. Here's a couple pix of pieces molded on the "normal" side. (The crevices are the bottom side of the raised part.)

PDXBarbara · Post by **PDXBarbara** » Sun Aug 10, 2003 6:37 pm

PDXBarbara (Bader) wrote:
I'll try plopping the problem area on the scanner ... if it works, you'll see what I mean.

Here are 2 scans. There are more at http://www.pbase.com/pdxbarbara/crystal ... ystery_pix if ya'll get excited about this problem...
Thanks guys...
BB
In the 2nd pic, the irid scratched off when I tried scrubbing off the white crystals... scrubbed with a scrotchbrite type thing & also tried a stiff brush. I stopped as soon as I saw what was happening.

Bob · Post by **Bob** » Mon Aug 11, 2003 9:54 am

Hi Barbara,

I am guessing but I have had several irid coatings give the effect in the image. Is the irid surface pitted? Do granules of glass pop out? I have had that occur under two circumstances. One is rare and occurs on fairly "normal" pieces (i.e. I didn't expect a problem). I think your piece falls in this category. I blamed it on being a problem with the glass... perhaps the coating wasn't fully bonded to the glass. From my experience it is pretty rare. The other circumstance is when irid coatings are stretched quite a bit during slumping, particularly over an abrupt edge such as the inside lip of a drop through mold. The problem area on your piece seems to be in the part that would have been slumped most during slumping.... perhaps it was just enough to accent the problem in the glass.

Please don't take this as an informed answer... just some observations.

Cheers,

Bob

PDXBarbara · Post by **PDXBarbara** » Mon Aug 11, 2003 11:58 am

Bob wrote:Hi Barbara,

I am guessing but I have had several irid coatings give the effect in the image. Is the irid surface pitted? Do granules of glass pop out? I have had that occur under two circumstances. One is rare and occurs on fairly "normal" pieces (i.e. I didn't expect a problem). I think your piece falls in this category. I blamed it on being a problem with the glass... perhaps the coating wasn't fully bonded to the glass. From my experience it is pretty rare. The other circumstance is when irid coatings are stretched quite a bit during slumping, particularly over an abrupt edge such as the inside lip of a drop through mold. The problem area on your piece seems to be in the part that would have been slumped most during slumping.... perhaps it was just enough to accent the problem in the glass.

Please don't take this as an informed answer... just some observations.

Cheers,

Bob

Hi Bob... thanks for helping me out.

I infer from your description (stretched irid) that as the irid stretches in the extreme part of the slump, it reveals the glass under it. In turn, that leaves the revealed bits vulnerable to devit/crystalizing. (yes?)

However, the swath of crud is actually in the least-slumped part...though adjacent to the most-slumped. Imagine the backside of the piece below. I used the same SS mold, but used the reverse side. So, in the screwed up piece, the irid is on the bottom...against the reverse side of the mold. Thus, the irid (bottom) of the screwed piece is shaped like the one in the pic below.

Here's a better pic of the location of the swath o' crystal weirdness.

So I guess this would fall under your observation #1? Even though the irid was fine during the 2 fuses that preceded the slump?

Thanks again, Bob...
Barbara

PDXBarbara · Post by **PDXBarbara** » Mon Aug 11, 2003 12:11 pm

P.S. your other questions, Bob....
Is the irid surface pitted?
YES.
Do granules of glass pop out?
No. Some of the crystals seem raised, tho.

Muchos gracias again, Bob.
xxoo
BB

Tony Smith · Post by **Tony Smith** » Mon Aug 11, 2003 1:00 pm

This sounds similar to the irid down problem that I've seen in the past, bust always with a black base glass... you can cratch the irid off with a fingernail and it's pitted under the surface.

no answers... just validation

Tony

PDXBarbara · Post by **PDXBarbara** » Mon Aug 11, 2003 1:12 pm

Tony Smith wrote:This sounds similar to the irid down problem that I've seen in the past, bust always with a black base glass... you can cratch the irid off with a fingernail and it's pitted under the surface.

no answers... just validation

Tony

Hi Tony...
YES. Do you think it's actually devit? Anyway, your description pretty much mirrors my crystal problem, tho mine doesn't involve black.
Have you experienced this problem with System 96 as well as BE?
Do you have any idea what it's from? Maybe I should get in touch w/ Ted Sawyer.
By the way... I've had similar crystalizing on he back of some highfires. But it's during fusing (1700 for 2 hours on fiber)... & irid not involved. (Tho I HAVE seen it on hifires where a sheet of BE irid down on fiber was under the rest of the glass. In that case, the bottom sheet cracked upon AFAP ramp up to process temp, and the crystals definitely congregated along the thermal-shock cracks.)
xxoo,, BB

Tony Smith · Post by **Tony Smith** » Mon Aug 11, 2003 2:12 pm

PDXBarbara (Bader) wrote:
Tony Smith wrote:This sounds similar to the irid down problem that I've seen in the past, bust always with a black base glass... you can cratch the irid off with a fingernail and it's pitted under the surface.

no answers... just validation

Tony
Hi Tony...
YES. Do you think it's actually devit? Anyway, your description pretty much mirrors my crystal problem, tho mine doesn't involve black.
Have you experienced this problem with System 96 as well as BE?
Do you have any idea what it's from? Maybe I should get in touch w/ Ted Sawyer.
By the way... I've had similar crystalizing on he back of some highfires. But it's during fusing (1700 for 2 hours on fiber)... & irid not involved. (Tho I HAVE seen it on hifires where a sheet of BE irid down on fiber was under the rest of the glass. In that case, the bottom sheet cracked upon AFAP ramp up to process temp, and the crystals definitely congregated along the thermal-shock cracks.)
xxoo,, BB

Go back a couple of weeks and read the thread on gold leaf and micas http://www.warmglass.com/phpBB/viewtopic.php?t=1772. I think you'll find that there are a number of people who have experienced this phenomenon with a number of different glasses. Ted Sawyer may be a good person to ask... but don't mention System 96.

Tony

PDXBarbara · Post by **PDXBarbara** » Mon Aug 11, 2003 2:29 pm

Tony Smith wrote: Go back a couple of weeks and read the thread on gold leaf and micas http://www.warmglass.com/phpBB/viewtopic.php?t=1772. I think you'll find that there are a number of people who have experienced this phenomenon with a number of different glasses. Ted Sawyer may be a good person to ask... but don't mention System 96.

I'll look it up, Tony. Thanks for the ref. FYI... Since I used BE glass, System 96 isn't germaine. I only asked you about it cause I have insatiable curiousity. (Like Curious George...)
BB

charlie · Post by **charlie** » Mon Aug 11, 2003 4:02 pm

PDXBarbara (Bader) wrote:
Tony Smith wrote: Go back a couple of weeks and read the thread on gold leaf and micas http://www.warmglass.com/phpBB/viewtopic.php?t=1772. I think you'll find that there are a number of people who have experienced this phenomenon with a number of different glasses. Ted Sawyer may be a good person to ask... but don't mention System 96.
I'll look it up, Tony. Thanks for the ref. FYI... Since I used BE glass, System 96 isn't germaine. I only asked you about it cause I have insatiable curiousity. (Like Curious George...)
BB

it's happened to me on the gold parts of purple translucent irid down against the shelf/mold, against b.e. wash.

PDXBarbara · Post by **PDXBarbara** » Mon Aug 11, 2003 6:32 pm

charlie wrote: it's happened to me on the gold parts of purple translucent irid down against the shelf/mold, against b.e. wash.

Hi Charlie.... hmmm.
I guess my next quesion is... do you know why it happened?
Thx.
Pdxbarbara

Lynne Chappell · Post by **Lynne Chappell** » Tue Aug 12, 2003 1:56 am

Most of us who have discussed this irid pitting, have seen it after fusing. However, it is much more evident after you have slumped it. It may have been there before you slumped, you just didn't see it.

Lynne

charlie · Post by **charlie** » Tue Aug 12, 2003 10:43 am

PDXBarbara (Bader) wrote:
charlie wrote: it's happened to me on the gold parts of purple translucent irid down against the shelf/mold, against b.e. wash.
Hi Charlie.... hmmm.
I guess my next quesion is... do you know why it happened?
Thx.
Pdxbarbara

i think it may have to do with the phase of the moon.

when iasked lani, she said that there was a batch of be wash that interacted badly with gold irid, when in direct contact. the factory sent me a different batch and i haven't had it replicated since. it looks to me like a bubbling between the irid and glass surfaces, and since it's irid down, the bubbles migrated upwards, causing deep pits in the glass. i would imagine if left for a very long time at fusing temps, they would migrate through the glass to the surface.

in my case, the pits were very large, on the order of 1/16"-1/8" or so in diameter.

Tony Smith · Post by **Tony Smith** » Tue Aug 12, 2003 12:55 pm

Charlie,

Was there a lot number or date associated with this "bad batch" of BE kilnwash???

Tony

charlie · Post by **charlie** » Tue Aug 12, 2003 12:59 pm

Tony Smith wrote:Charlie,

Was there a lot number or date associated with this "bad batch" of BE kilnwash???

Tony

i don't know offhand, and wasn't told. tonight i'll check the two buckets to see if there's any identifying numbers on them.

charlie · Post by **charlie** » Wed Aug 13, 2003 12:06 am

charlie wrote:
Tony Smith wrote:Charlie,

Was there a lot number or date associated with this "bad batch" of BE kilnwash???

Tony
i don't know offhand, and wasn't told. tonight i'll check the two buckets to see if there's any identifying numbers on them.

the bad container has a code of 121899, the good container code is 012803, which i suspect is a date code. the bad lot probably spans a range of dates.

PDXBarbara · Post by **PDXBarbara** » Wed Aug 13, 2003 12:11 am

[quote="charlie"][quote="charlie"]

I'm gonna check my wash tomorrow! Thx.
BB

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