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Pattern Bar: Flow Slab

For discussion and commentary regarding the Lesson and Project videos of the Bullseye Kiln-Glass Education Online program.

Re: Pattern Bar: Flow Slab

Postby hunclecharlie » Tue Sep 24, 2013 10:57 am

lsuder@calhospital.org wrote:
More likely, I think, your thoughts about the size of my piece relative to the size of the kiln are the key. There was a lot of thermal mass at the edges of the piece with not a lot of room for air circulation around the edges. Despite what I thought was a conservative annealing schedule, I expect the center of the piece cooled faster.


It looks like a top fired kiln. I think you are right about the size of the piece and the lack of air circulation. The upshot is that the center of the bottom of your kiln is ice cold and the center of the shelf is cooling your glass too fast from bellow. You may be able to make it work by raising the shelf but the best thing would be to get another kiln if you want to do pieces this big. You need an element in the walls below the level of the shelf or an element in the floor.

I once fired a three inch thick piece three times before I finally moved it to my big kiln that has floor elements. Made all the difference.
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Re: Pattern Bar: Flow Slab

Postby amvanbrunt » Sat Jul 26, 2014 6:34 am

Hello
I recreated your pattern bar flow slab and had wonderful results.
You didn't say how thick you cut the pieces after you had removed the edges.
It looks to me like they are about 1/2 inch thick....but I was planning on cutting my pieces into 1/4 inch slices...would that re-fire the same as your heating schedule of 1490 for 20 minutes?

I soooo enjoy having this resource .....I am learning so much from your video's and am so inspired now!

Thanks
Anne-Marie
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Re: Pattern Bar: Flow Slab

Postby marykaynitchie » Wed Jul 30, 2014 10:26 am

Hi Anne-Marie,

Bullseye instructor Louise is on the road, but she got in touch with me via email:

We cut the bars 1cm thick on the saw, then design plates/panels out of 3 layers of sheet glass (9mm/10mm is the desired thickness of our final piece). You may want to cut thicker slices, if you intend to make a thicker panel in the end.


Does that help at all? I think you can start with the same cycle that is shown for the projects in the video lesson.

Mary Kay
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Re: Pattern Bar: Flow Slab

Postby amvanbrunt » Fri Aug 01, 2014 7:41 am

Thanks Louise and Mary Kay!
That information will help as I take the next step.
Will let you know how it turns out!

Anne-Marie
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Re: Pattern Bar: Flow Slab

Postby bgswenson13 » Fri Aug 15, 2014 2:43 pm

Is a transcript of the video lesson available?
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Re: Pattern Bar: Flow Slab

Postby marykaynitchie » Fri Aug 15, 2014 3:30 pm

Hi,

We don't usually provide transcripts--however, I would like to learn more about your request. I will contact you via email.

Mary Kay
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Re: Pattern Bar: Flow Slab

Postby russf » Sun Aug 24, 2014 9:03 am

In your post here http://www.bullseyeglass.com/forum/index/viewtopic.php?f=22&t=3474&start=40#p7039 I notice there is striped yellow/white coloration on the shelf.

Is is possible this was caused by an interaction between the shelf and the work? I find that white opal tends to stick aggressively to my kilnwash, especially above 800C, often lifting it off the shelf. If instead of the wash lifting, the glass movement is impeded, this might cause cracking. I've seen that on one piece where chips of glass had to be ground from the shelf after cooling.

Did you reach any conclusion other than moving to smaller work size, or top & bottom heating?
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Re: Pattern Bar: Flow Slab

Postby marykaynitchie » Fri Aug 29, 2014 11:01 am

A cautionary tale:

We recently saw a pattern bar piece with little bits of gray and white contamination all throughout the surface in the Research and Education department. After looking at the piece under a magnifier, the gray was identified as silicon carbide and the white as glass dust. The maker had coldworked the entire surface of the piece, opening up the many tiny champagne bubbles just below the skin, which filled with grit and glass dust.

Please note that if you are using loose carbide grits to coldwork your piece, cleaning is important. In addition to wiping the surface with cleaner, we recommend using some sort of pressure washer or compressed air to clean the holes before firing.

I will post this in the discussion re the loose grits video lesson, too.

Mary Kay
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Re: Pattern Bar: Flow Slab

Postby Twin Vision Glass » Fri Aug 29, 2014 4:00 pm

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I have been following this thread with great interest and perhaps this might be a thought for Anne-Marie asking how thick should you cut the slices from the bar. I cut thick, thin, long , short, sideways, up and down, always thinking of how or what I want to say in the finished piece I am creating . I have a hard time making perfect colour bars , and love layering and slicing through and controlling bubbles that will draw the glass upward as it melts. When I go to put them together if I want a thicker piece BUT want to get as many slices out of the bar, I will saw as thin as I can go, CLEAN right away by scrubbing with a scrubby and lay out to dry getting all the sludge off them, then if I want thicker cast piece, I will layer clear glass or 1401 frit on top. Add frit in between or underneath or just about any way your creative spirit takes you. Have fun. These pieces turned out to be 2 inchs thick. Lots of fun. Almost looks like a tree trunk.
Leslie
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Re: Pattern Bar: Flow Slab

Postby rstarlightcreations » Mon Dec 29, 2014 5:30 pm

I viewed the lesson over and over. Just one concern does the flow slab always have to be 2 cm thick or can it be calculated to be 6 mm. :?:
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