New needling problem (Solved)

jim simmons · Post by **jim simmons** » Mon Jun 16, 2003 12:34 pm

I just ran into an interesting situation.
All of a sudden I started to have needling problems when fusing BE glass at 1480 F. for 10 min.

I lowered the hold time to 7 min and then the joints between the pieces of glass on the top didn't completely run together. (There was a slight indent between the pieces of glass.) + there was still a little needling.

I measured the thickness of the fired piece, and guess what? It was only 0.235 inches thick instead of 0.25 +. What was going on?

I then measured the individual pieces from the original sheets and found out that the clear base layer was only 0.105 inches thick instead of 0.125 inches.

It turned out that the base layer was Uroboros machine rolled clear. I then measured all of the sheets of Uroboros machine rolled clear that I had and they ALL measured 0.105 inches or less thick.

I guess that what I am trying to say, is, If you start to have needling problems look at the thickness of the starting layers.

I am having to use a layer of BE thin on top of the Uroboros clear to eliminate this problem.

Somethingneweverydayboy (Jim)

michey · Post by **michey** » Tue Jun 17, 2003 3:42 am

Thank you for taking the time to post this. You just solved my problem too. Just knew it had to be a 'duh' answer but the answer hadn't come to me yet. Received a new shipment of purple, in thin rather than regular and have been having minor needling. Until you mentioned your solution it hadn't occured to me my last batch was regular thickness instead of thin.

Lani McGregor · Post by **Lani McGregor** » Tue Jun 17, 2003 8:40 am

?ve been wondering when someone was going to notice this.

Many users donâ€™t realize that most System 96 glass is 15-20% thinner than BE. So what?

In your case you had to use more glass to avoid needle-pointing.

I wonder if anyone has noticed anything else that relates to this?

Trying not to slam the competition, but there IS some valuable information that someone with a good understanding of kilnforming could deduce from this difference in sheet thickness.

(not going to be me)

-Lani

Michael McNerney · Post by **Michael McNerney** » Tue Jun 17, 2003 8:56 am

Lani,
I have noticed another problem in this topic area.
Bullseye Double rolled clear will usually pull needles betwween 1450 and 1500 if it is fired on fiberpaper (not usually a problem on ceramic washed shelves). I have only had this problem when using clear as a base and capping with another color.

Michael

Lani McGregor · Post by **Lani McGregor** » Tue Jun 17, 2003 9:27 am

Michael,

Are you referring to Bullseye's "double-rolled" clear or our "machine-rolled" clear?

-Lani

jim simmons · Post by **jim simmons** » Tue Jun 17, 2003 11:26 am

Lani McGregor wrote:Michael,

Are you referring to Bullseye's "double-rolled" clear or our "machine-rolled" clear?

-Lani

Does BE have machine rolled clear again, or are you refering to the old glass.

Jim

Jo Holt · Post by **Jo Holt** » Tue Jun 17, 2003 8:04 pm

Lani McGregor wrote:?ve been wondering when someone was going to notice this.

Many users donâ€™t realize that most System 96 glass is 15-20% thinner than BE. So what?

In your case you had to use more glass to avoid needle-pointing.

I wonder if anyone has noticed anything else that relates to this?

Trying not to slam the competition, but there IS some valuable information that someone with a good understanding of kilnforming could deduce from this difference in sheet thickness.

(not going to be me)

-Lani

Well, I'm working on that "good understanding of kilnforming" but I'm not there yet.

I don't use system 96 but I do use std Spectrum some. I use baroque and waterglass so the glass sheet thickness isn't as obvious because of the texture variations; that said, I felt BE was slightly thicker. I do notice the BE *flows* better. I thought the COE might be why but maybe not. Is it that BE has a tighter melt-flow range? This is why it's so consistent?

Jo (who needs to learn more!)

Tony Smith · Post by **Tony Smith** » Tue Jun 17, 2003 10:10 pm

Lani McGregor wrote: I've been wondering when someone was going to notice this.

Many users don?t realize that most System 96 glass is 15-20% thinner than BE. So what?

In your case you had to use more glass to avoid needle-pointing.

I wonder if anyone has noticed anything else that relates to this?

Trying not to slam the competition, but there IS some valuable information that someone with a good understanding of kilnforming could deduce from this difference in sheet thickness.

(not going to be me)

-Lani

Lani,

Always one to rise to a technical challenge, I just went down to my studio with my trusty micrometer and measured 33 different pieces of glass... all System 96. I didn't select them for anything other than variety. I wanted to make sure that I had representative pieces from as many different runs as possible, so I used different colors to choose my glass. Only one piece of clear and only one piece of black glass were used in the measurements. Any pieces of the same color (there were a couple) were from different sources (east coast vs west coast) and purchased at different times.

I measured each piece four times to get an idea of the variation within each piece of glass (most were approximately 12" square)... so I measured each of four corners. I calculated the average (mean) thickness for each piece.

Target thickness = 3mm = 0.1181"
# Pieces = 33
std deviation (all measurements) = 0.0083"
min thickness (all measurements) = 0.099"
max thickness (all measurements) = 0.135"
mean thickness (all measurements) = 0.1153"
median thickness (all measurements) = 0.1145"

Averaging the thicknesses per piece gives the following data:
std deviation = 0.0069"
min thickness = 0.1028"
max thickness = 0.1275"
mean thickness = 0.1153"
median thickness = 0.1163"

While there were some sheets that were surprisingly thin, the bulk of the numbers are very close to the target of 0.1181"

Unfortunately, I don't have access to a large variety of BE glass or I would provide comparison measurements. Ron? Phil?

Tony

jim simmons · Post by **jim simmons** » Wed Jun 18, 2003 12:48 am

Lani,

Always one to rise to a technical challenge, I just went down to my studio with my trusty micrometer and measured 33 different pieces of glass... all System 96. I didn't select them for anything other than variety. I wanted to make sure that I had representative pieces from as many different runs as possible, so I used different colors to choose my glass. Only one piece of clear and only one piece of black glass were used in the measurements. Any pieces of the same color (there were a couple) were from different sources (east coast vs west coast) and purchased at different times.

I measured each piece four times to get an idea of the variation within each piece of glass (most were approximately 12" square)... so I measured each of four corners. I calculated the average (mean) thickness for each piece.

Target thickness = 3mm = 0.1181"
# Pieces = 33
std deviation (all measurements) = 0.0083"
min thickness (all measurements) = 0.099"
max thickness (all measurements) = 0.135"
mean thickness (all measurements) = 0.1153"
median thickness (all measurements) = 0.1145"

Averaging the thicknesses per piece gives the following data:
std deviation = 0.0069"
min thickness = 0.1028"
max thickness = 0.1275"
mean thickness = 0.1153"
median thickness = 0.1163"

While there were some sheets that were surprisingly thin, the bulk of the numbers are very close to the target of 0.1181"

Unfortunately, I don't have access to a large variety of BE glass or I would provide comparison measurements. Ron? Phil?

Tony[/quote]

I didn't go as far as Tony, But I found something that I thought was strange.

I measured the system 96 clear glass in my studio and found this.
4 pieces were measured at the corners like tony.
The average was taken, but I didn't do the std dev.

1= 0.124
2. 0.118
3. 0.118
4. 0.124.

NOW the interesting thing.

I did the same with 6 pieces of "Uroboros" clear glass and came up with these numbers.

1. 0.109
2. 0.114
3. 0.105
4. 0.110
5. 0.109
6. 0.109.

Can anyone explain the difference? I sure can't

Jim

Brock · Post by **Brock** » Wed Jun 18, 2003 12:54 am

Am I missing something here?

Oroboros is thinner than Spectrum which is thinner than Bullseye.

Next?

Brock

Lani McGregor · Post by **Lani McGregor** » Wed Jun 18, 2003 1:17 am

Tony Smith wrote: While there were some sheets that were surprisingly thin, the bulk of the numbers are very close to the target of 0.1181"

Tony

Tony, why do you say the "target" is 0.1181" ?

The testing published by System 96 to prove their longer working range is based on the premise that a single layer of their glass is 1/8" or 0.125"

-Lani

David Williams · Post by **David Williams** » Wed Jun 18, 2003 1:41 am

Trying not to slam the competition, but there IS some valuable information that someone with a good understanding of kilnforming could deduce from this difference in sheet thickness.

Bullseye is sold by the pound?

David Williams · Post by **David Williams** » Wed Jun 18, 2003 1:43 am

[quote="Brock"]Am I missing something here?

Oroboros

Yep, missing a capital 'U'.

Brock · Post by **Brock** » Wed Jun 18, 2003 1:48 am

David Williams wrote:Trying not to slam the competition, but there IS some valuable information that someone with a good understanding of kilnforming could deduce from this difference in sheet thickness.

Bullseye is sold by the pound?

Spectrum is more expensive than it seems?

Brock

Brock · Post by **Brock** » Wed Jun 18, 2003 1:49 am

David Williams wrote:
Brock wrote:Am I missing something here?

Oroboros

Yep, missing a capital 'U'.

Good one David. Where's the hana you'ved owed me for 2 years? Brock

Tony Smith · Post by **Tony Smith** » Wed Jun 18, 2003 7:29 am

Lani McGregor wrote:
Tony Smith wrote: While there were some sheets that were surprisingly thin, the bulk of the numbers are very close to the target of 0.1181"

Tony
Tony, why do you say the "target" is 0.1181" ?

The testing published by System 96 to prove their longer working range is based on the premise that a single layer of their glass is 1/8" or 0.125"

-Lani

It's not the first time that I've missed something like that... none of their regular literature mentions the thickness. I had only seen references to 3mm, but maybe that was for some special thinner sheets.

I stand corrected. That makes their mean off target by 8.5%. I suppose if you were trying to pinch pennies over the long haul, using 8.5% less glass in your manufacturing process would be one way to do it.

Tony

Lani McGregor · Post by **Lani McGregor** » Wed Jun 18, 2003 9:09 am

Tony Smith wrote:
Lani McGregor wrote:
Tony Smith wrote: While there were some sheets that were surprisingly thin, the bulk of the numbers are very close to the target of 0.1181"

Tony
Tony, why do you say the "target" is 0.1181" ?

The testing published by System 96 to prove their longer working range is based on the premise that a single layer of their glass is 1/8" or 0.125"

-Lani
It's not the first time that I've missed something like that... none of their regular literature mentions the thickness. I had only seen references to 3mm, but maybe that was for some special thinner sheets.

I stand corrected. That makes their mean off target by 8.5%. I suppose if you were trying to pinch pennies over the long haul, using 8.5% less glass in your manufacturing process would be one way to do it.

Tony

Tony,

Now, what if you did a comparative test, fusing three of those "1/8 inch" layers of Spectrum and three 1/8 inch layers of BE, slumped them into a trough and measured the width of the resulting puddle in order to prove something about the "working range" of Spectrum?

(http://www.system96.com/Pages/WorkingRange.html)

What conclusion might you reach?

-Lani

Tony Smith · Post by **Tony Smith** » Wed Jun 18, 2003 10:09 am

Lani McGregor wrote:
Tony,

Now, what if you did a comparative test, fusing three of those "1/8 inch" layers of Spectrum and three 1/8 inch layers of BE, slumped them into a trough and measured the width of the resulting puddle in order to prove something about the "working range" of Spectrum?

(http://www.system96.com/Pages/WorkingRange.html)

What conclusion might you reach?

-Lani

Gee Lani, couldn't you have made this a multiple choice quiz?

Well, I guess that would depend on how you define "use similar glasses and thicknesses from each family". http://www.system96.com/Pages/WorkingRange.html

That says to me that Gil used "similar glasses and thicknesses from each family". Since I prefer a more quantitative approach, it tells me very little... had he measured the glass thicknesses with more precision than referring to 1/8" or 3/8" thicknesses the test would have been more meaningful, but it still would not have made a strong case for one glass over another. People learn to work with their glass regardless of what the numbers say. If BE glass puddled to the bottom of everyone's molds at slumping temperatures, they would have stopped using it long before now. .. but that's not what the test shows... it shows that at fusing temperature, the glass flows downhill... so what?

As with any of the glasses, you learn that varying your temperature by 25Â° or changing your soak by 10 minutes can make a big difference in the texture and look of your fused glass. Most of the fusers that I've met pick a family of fusible glass and work with it until they get the results that they like. The reasons that they choose one family over another vary from what their local retailer carries, to what their first teacher taught them with, to what they read about in magazines or on this board. It takes working with the glass for awhile before they even understand what Gil was talking about (if ever), and by that time, they have so much invested in one glass family that it doesn't make sense to change. I had never read that article until this morning. I'm not sure how many people have been influenced by it, but I would suspect that the numbers are very small.

As far as the original point regarding needling, since I use almost all System 96 glass, I haven't noticed it as a problem... in fact other than when I'm doing casting with a fiberpaper border along the sides, I haven't seen it at all.

Tony

David Williams · Post by **David Williams** » Wed Jun 18, 2003 12:20 pm

Now, what if you did a comparative test, fusing three of those "1/8 inch" layers of Spectrum and three 1/8 inch layers of BE, slumped them into a trough and measured the width of the resulting puddle in order to prove something about the "working range" of Spectrum?

(http://www.system96.com/Pages/WorkingRange.html)

What conclusion might you reach?

-Lani[/quote]

I suggested that same test to Spectrum years ago. It might even be in the archives here. But I sugested it as a viscosity test when their new 100fs first came out, as proof the viscosity was way too low. Not between manufacturers. I would think anyone doing that test would be smart enough to measure the thicknesses of the sheets cold, and compare the relative width and height of the finished tests as a percentage of their original sizes. For viscosity. But as a test for "working range" I'm not sure. The truth is I don't even know what working range means in a kiln. I know what it means in off-hand work; recently i've compared my normal Spectrum cullet to Seattle batch cullet. I can say that Spectrum did have a shorter working range, but paradoxically a lower viscosity given the same relative heating. The spectrum would tend to soften up and freeze up more quickly while the SBC would stay steady longer.