I have noticed in firing 8 and 12 in blanks that bubbles seem to appear only where the glass is two layers thick and hardly at all where it is three layers thick. If I use 2 layers Spectrum and then a pattern on top, the bubbles only appear where the pattern is not. (for example if the third layer is a lizard on top of two layers of clear, the bubbles are only where the lizard is not) They are between the glass and do not break the surface, but distort the top surface quite badly.
In pieces where I have used two layers of glass with just a few stringers on top as decoration there are tons of bubbles everywhere. In pieces where the design on top (third layer) almost totally covers the piece they are hardly visible.
It's amost like the the extra weight or extra temp in this area squeezes them out. Does anyone have any thoughts on this???
My fusing sched is 350 - 1000- 0/ 300 - 1452 - 8/ AFAP - 1000 - 8/ 300 - 955 - 20/ 200 - 800 - 0 / 400 - off.
I tried a higher fire to 1465, but the results were similar.
Thanks for any thoughts or suggestions.
Janine
Is three layers hotter than two?
Moderators: Brad Walker, Tony Smith
Re: Is three layers hotter than two?
You've figured it out. The bubbles are going to come up in areas of least resistance, unless you have trapped air in specific places due to design elements between the top and bottom layer.
The trick, is to not have bubbles at all. In the size pieces you are describing you should be able to avoid bubbles by tweaking your firing schedule. A hold at 1150-1200 should allow most trapped air to escape between layers, and if that isn't effective, you'll have to try beads around the perimeter of your piece. Brock
The trick, is to not have bubbles at all. In the size pieces you are describing you should be able to avoid bubbles by tweaking your firing schedule. A hold at 1150-1200 should allow most trapped air to escape between layers, and if that isn't effective, you'll have to try beads around the perimeter of your piece. Brock
My memory is so good, I can't remember the last time I forgot something . . .
Thanks Brock, I will try that. I have tried many of the suggestions regarding bubbles on this board including beads. I think my problem may also be linked to my ceramics kiln. I used to be a professional potter, and my favorite glaze was a "crater glaze", looked cool on pots but..... While a lot of the knowledge is transferable some habits die hard.
Thanks again.
Janine
Thanks again.
Janine
Hey Brock this is the Robert from the studio in Burnaby days , NZ and
other places now in Portland . We can catch up later but for the sake of
the forum heres a glass problem I am trying to solve . First tried a test
ala BULLseye tipsheet 3 working deep . For some reason that always
makes me think of deep throat . test was single firing 1 inch thick with
some color chips and in spite of what is said on the tipsheet a single
firing can`t be done without bubble city . I need to make 3 shelves
1 inch thick 60 inches long 14 inches wide rolled or beveled edges and
I hope to avoid cold work . Some bubbles are acceptable as long as they
don`t break the surface . I will do two firings for each piece , one to
fuse the color on the surface of two sheets , second firing to fuse the
stack of clear and color together . Besides the bubble question which
may be solved what options are there to eliminate the cut seams . If
I soak too long am I not asking for more bubbles to travel to the surface ? All pearls of wisdom gratefully acceptable .
Robert
other places now in Portland . We can catch up later but for the sake of
the forum heres a glass problem I am trying to solve . First tried a test
ala BULLseye tipsheet 3 working deep . For some reason that always
makes me think of deep throat . test was single firing 1 inch thick with
some color chips and in spite of what is said on the tipsheet a single
firing can`t be done without bubble city . I need to make 3 shelves
1 inch thick 60 inches long 14 inches wide rolled or beveled edges and
I hope to avoid cold work . Some bubbles are acceptable as long as they
don`t break the surface . I will do two firings for each piece , one to
fuse the color on the surface of two sheets , second firing to fuse the
stack of clear and color together . Besides the bubble question which
may be solved what options are there to eliminate the cut seams . If
I soak too long am I not asking for more bubbles to travel to the surface ? All pearls of wisdom gratefully acceptable .
Robert
Hey Robert, nice to see you here. I'm kinda brain dead right now but . . .
My working deep tile, about 8" suare and 1 1/8" deep is absolutely full of bubbles, and I think they're absolutely gonna be there in your pieces also.
You could try flipping the piece for the second firing? Fire it face down, then flip and fire polish?
Seams . . . I don't know, they're pretty visible in clear glass.
Not much help, but I'm sure someone will have an idea. Brock
My working deep tile, about 8" suare and 1 1/8" deep is absolutely full of bubbles, and I think they're absolutely gonna be there in your pieces also.
You could try flipping the piece for the second firing? Fire it face down, then flip and fire polish?
Seams . . . I don't know, they're pretty visible in clear glass.
Not much help, but I'm sure someone will have an idea. Brock
My memory is so good, I can't remember the last time I forgot something . . .
-
Catharine Newell
- Posts: 83
- Joined: Thu Mar 13, 2003 12:33 am
- Location: Portland, OR
Hello Robert,
I do a fair number of pretty thick (BE glass) pieces - 3/4 to 1" thick panels - and have found the following steps to be helpful in preventing surface bubbling (which occurs sometimes anyway, for whatever reason): I pre-fuse 1/4 layers prior to stacking; for the (second) stack firing, I would probably ramp up 6 hrs to 1100, soak 1 hr/ 50 dph to 1240, soak 1 hr/ AFAP to 1480, soak 20 mins...
I'm assuming you're talking about the end seams on the sides of the stack? BE's recommendation of sidewalls sounds like a good idea to solve your question, there...
Catharine
I do a fair number of pretty thick (BE glass) pieces - 3/4 to 1" thick panels - and have found the following steps to be helpful in preventing surface bubbling (which occurs sometimes anyway, for whatever reason): I pre-fuse 1/4 layers prior to stacking; for the (second) stack firing, I would probably ramp up 6 hrs to 1100, soak 1 hr/ 50 dph to 1240, soak 1 hr/ AFAP to 1480, soak 20 mins...
I'm assuming you're talking about the end seams on the sides of the stack? BE's recommendation of sidewalls sounds like a good idea to solve your question, there...
Catharine
Hi Catherine
Thanks for the info . Because these pieces are 60 inches long and no COE 90 is available in that length [ I also have to do one 87 inches }
I am cutting sheets , laying them out to get the length . Its those edge
to edge seams I would like to go away . Have you tried flip firing one
1/4 inch stack on top of the whole stack for the last firing ? Maybe that
would be as good as it gets . Its all clear glass for the most part .
Another thought is using billets in the right volume , weight for the
last firing on top of the prefired 1/4 inch layer . Anyone had experience
with this ? Maybe the temp required would suck bubbles up . I plan to
use clear irid on the edges .
Robert
Thanks for the info . Because these pieces are 60 inches long and no COE 90 is available in that length [ I also have to do one 87 inches }
I am cutting sheets , laying them out to get the length . Its those edge
to edge seams I would like to go away . Have you tried flip firing one
1/4 inch stack on top of the whole stack for the last firing ? Maybe that
would be as good as it gets . Its all clear glass for the most part .
Another thought is using billets in the right volume , weight for the
last firing on top of the prefired 1/4 inch layer . Anyone had experience
with this ? Maybe the temp required would suck bubbles up . I plan to
use clear irid on the edges .
Robert
-
Catharine Newell
- Posts: 83
- Joined: Thu Mar 13, 2003 12:33 am
- Location: Portland, OR
Robert,Robert Middlestead wrote:Hi Catherine
Thanks for the info . Because these pieces are 60 inches long and no COE 90 is available in that length [ I also have to do one 87 inches }
I am cutting sheets , laying them out to get the length . Its those edge
to edge seams I would like to go away . Have you tried flip firing one
1/4 inch stack on top of the whole stack for the last firing ? Maybe that
would be as good as it gets . Its all clear glass for the most part .
Another thought is using billets in the right volume , weight for the
last firing on top of the prefired 1/4 inch layer . Anyone had experience
with this ? Maybe the temp required would suck bubbles up . I plan to
use clear irid on the edges .
Robert
I don't see why flip firing the last 1/4 inch layer wouldn't work, as long as it's prefired to eliminate any bubble entrapment. I've added one last layer to a fired stack numerous times, with good results - but never flip fired. I'm wondering, tho, how that would solve your seam problem? You still have that 5' length to deal with. Even though you're using clear glass for the most part, couldn't you arrange the clear in some sort of design to hide the fact that you're adding length?
Regarding bubbling, I think flip firing the entire stack would be a good thing to investigate - let the bubbles rise to the back of the piece.
Would you post what you decide to do about your length quandary? It's something that I come up against in my panels... I have tended to avoid the question by just sticking to the 35" length of the BE sheets. Rather limiting...
Catharine
-
Doug Randall
- Posts: 102
- Joined: Sun Aug 17, 2003 10:11 pm
- Location: Portland, OR
- Contact:
Catharine Newell wrote:Robert,Robert Middlestead wrote:Hi Catherine
Thanks for the info . Because these pieces are 60 inches long and no COE 90 is available in that length [ I also have to do one 87 inches }
I am cutting sheets , laying them out to get the length . Its those edge
to edge seams I would like to go away . Have you tried flip firing one
1/4 inch stack on top of the whole stack for the last firing ? Maybe that
would be as good as it gets . Its all clear glass for the most part .
Another thought is using billets in the right volume , weight for the
last firing on top of the prefired 1/4 inch layer . Anyone had experience
with this ? Maybe the temp required would suck bubbles up . I plan to
use clear irid on the edges .
Robert
I don't see why flip firing the last 1/4 inch layer wouldn't work, as long as it's prefired to eliminate any bubble entrapment. I've added one last layer to a fired stack numerous times, with good results - but never flip fired. I'm wondering, tho, how that would solve your seam problem? You still have that 5' length to deal with. Even though you're using clear glass for the most part, couldn't you arrange the clear in some sort of design to hide the fact that you're adding length?
Regarding bubbling, I think flip firing the entire stack would be a good thing to investigate - let the bubbles rise to the back of the piece.
Would you post what you decide to do about your length quandary? It's something that I come up against in my panels... I have tended to avoid the question by just sticking to the 35" length of the BE sheets. Rather limiting...
Catharine
Picking up glass at the factory the other day I saw what looked like stacks of 3' x 6 or 7' CLEAR. (not certain of the exact size but I know it was big) Its being made but I'm not sure of its availability at present. Contact a rep at BE for any details.
Catherine
I am seriously thinking of moving over to Spectrum as they are open
to running longer sheets in case lots . If you want some longer sheets
lets talk maybe we can share a case .I am taking out two prefired 1/4
layers today and let you know what direction I go next . It seems bigger
is not always better .
I am seriously thinking of moving over to Spectrum as they are open
to running longer sheets in case lots . If you want some longer sheets
lets talk maybe we can share a case .I am taking out two prefired 1/4
layers today and let you know what direction I go next . It seems bigger
is not always better .
Catherine
I am seriously thinking of moving over to Spectrum as they are open
to running longer sheets in case lots . If you want some longer sheets
lets talk maybe we can share a case .I am taking out two prefired 1/4
layers today and let you know what direction I go next . It seems bigger
is not always better .
Robert
I am seriously thinking of moving over to Spectrum as they are open
to running longer sheets in case lots . If you want some longer sheets
lets talk maybe we can share a case .I am taking out two prefired 1/4
layers today and let you know what direction I go next . It seems bigger
is not always better .
Robert
-
Catharine Newell
- Posts: 83
- Joined: Thu Mar 13, 2003 12:33 am
- Location: Portland, OR
Doug, that's Dan's new GIANT annealer! Very exciting to think of those big sheets rolling out of the factory...Doug Randall wrote:Catharine Newell wrote:Robert,Robert Middlestead wrote:Hi Catherine
Thanks for the info . Because these pieces are 60 inches long and no COE 90 is available in that length [ I also have to do one 87 inches }
I am cutting sheets , laying them out to get the length . Its those edge
to edge seams I would like to go away . Have you tried flip firing one
1/4 inch stack on top of the whole stack for the last firing ? Maybe that
would be as good as it gets . Its all clear glass for the most part .
Another thought is using billets in the right volume , weight for the
last firing on top of the prefired 1/4 inch layer . Anyone had experience
with this ? Maybe the temp required would suck bubbles up . I plan to
use clear irid on the edges .
Robert
I don't see why flip firing the last 1/4 inch layer wouldn't work, as long as it's prefired to eliminate any bubble entrapment. I've added one last layer to a fired stack numerous times, with good results - but never flip fired. I'm wondering, tho, how that would solve your seam problem? You still have that 5' length to deal with. Even though you're using clear glass for the most part, couldn't you arrange the clear in some sort of design to hide the fact that you're adding length?
Regarding bubbling, I think flip firing the entire stack would be a good thing to investigate - let the bubbles rise to the back of the piece.
Would you post what you decide to do about your length quandary? It's something that I come up against in my panels... I have tended to avoid the question by just sticking to the 35" length of the BE sheets. Rather limiting...
Catharine
Picking up glass at the factory the other day I saw what looked like stacks of 3' x 6 or 7' CLEAR. (not certain of the exact size but I know it was big) Its being made but I'm not sure of its availability at present. Contact a rep at BE for any details.
C.
BE has 40 inch sheets and is working on making longer sizes . UB only
has their standard size sheets in stock . I am across the road from
them in Portland . So far I am making longer sheets pre - fusing 1/4
layers then stacking two of those with four more sheets of clear . One
of these is cooking now so will post the results after Thur .
Robert
has their standard size sheets in stock . I am across the road from
them in Portland . So far I am making longer sheets pre - fusing 1/4
layers then stacking two of those with four more sheets of clear . One
of these is cooking now so will post the results after Thur .
Robert