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Help! Issue with cut / ground edges!

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Help! Issue with cut / ground edges!

Postby hewoo2 » Sun Jul 08, 2018 12:04 pm

Hoping someone can help me with my issue; I'm at the end of ideas to try!

I have been trying utilize a tile saw to create more regularly-sized pieces for my jewelry designs. The process:

- Bullseye 90CoE glass strips fused for 10 min @ 1425 in Skutt kiln. No devit issues.
- These strips are then cut on an MK101 tile saw using a Husqvarna Superlok Glass blade.
- After scrubbing with toothbrush and clean towel they are fused again for 15 min @ 1425 for desired roundness and gloss.

Unfortunately, the cut edges have a grey hazy 'scar' that seems be sealed into/under the fire gloss.

Cut edge scarring
GrindEdge01.jpg (186.67 KiB) Viewed 8448 times

Cut edge scarring
GrindEdge02.jpg (121.33 KiB) Viewed 8448 times

Cut edge scarring
GrindEdge03.jpg (112.73 KiB) Viewed 8448 times

I thought this might be devit, but no other surfaces show any issues / contamination, and the 'scar' is glassed over, not on the surface. Glass pieces that are snap-cut rather than ground/saw-cut and fired in the same batch are absolutely perfect with no devit, so I have ruled out kiln contamination.

I have tried a number of different things to get rid of this:

- Grind all cut edges with a wet grinder, clean with ISO. No difference.
- Wet-sand all cut edges with Covington wet sander / silicon paper, clean with ISO. No difference.
- Wet-sand with progressively finer sand paper up to 600 grit, clean with ISO. No difference.
- Difference firing schedules, including a hold at fire-gloss temp, then raise to 1425 for final. No difference.

I'm at wit's end!
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Joined: Sun Jul 08, 2018 10:52 am

Re: Help! Issue with cut / ground edges!

Postby Kevin Midgley » Sun Jul 08, 2018 3:54 pm

dirty saw cuts!
keep wet.
Once dried impossible to clean.
Kevin Midgley
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Re: Help! Issue with cut / ground edges!

Postby jslowsky » Mon Jul 09, 2018 7:40 am

Tried that... cut, dropped into a bowl of water before cleaning with brush. Nope... that isn't the answer. I am suspicious if it is the Tecca glass (clear) from Bullseye. It only effects those edges that have been cut with a diamond blade or trimmed with a grinder wheel.
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Re: Help! Issue with cut / ground edges!

Postby hewoo2 » Tue Jul 10, 2018 6:09 am

I had read that cleaning was a serious issue, so my current workflow is to cut on the saw and drop into a bowl of water. From there I scrub with a toothbrush and dry with a clean cloth. Maybe that's not enough? Seems so strange to me that the glass won't melt/merge properly in these areas.

We thought some residual debris was getting left by the saw blade, so we tried doing a grind / sand pass before final clean/dry with no improvement.

My thinking now is that there is something wrong with the glass. We'll be doing a test with 96CoE to see if that yields any improvement.
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Joined: Sun Jul 08, 2018 10:52 am

Re: Help! Issue with cut / ground edges!

Postby marykaynitchie » Tue Jul 17, 2018 2:04 pm

Let us know what you find out. The advice to keep the edges wet and then thoroughly cleaning them sounds right.

Mary Kay
Mary Kay Nitchie
Bullseye Glass Co.

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Re: Help! Issue with cut / ground edges!

Postby jestersbaubles » Thu Jul 19, 2018 7:21 pm

Are you firing on ThinFire or firing on a kiln-washed shelf? If firing on ThinFire, I would experiment with kiln wash.

I am a System 96 user, but I have seen many comments from people firing BE glass (and particularly Tekta) on ThinFire and getting devit. You could also use a devit agent on the edges, or on all sides but the back.

Dana W.
Dana Worley Fused Glass Designs
dba Jester's Baubles
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Re: Help! Issue with cut / ground edges!

Postby nkimmanley » Sat Jul 21, 2018 3:29 am

Put a drop of detergent in the water you are dropping your cut slices into, it helps by reducing surface tension, and the ground glass is less likely to stick to the surface.
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Joined: Sun Dec 18, 2011 5:38 pm

Re: Help! Issue with cut / ground edges!

Postby ejgiebel » Thu Aug 09, 2018 9:20 am

I have a lot of toys in my studio, but I almost always put the edges of my cut pieces on an old 220 grit disk on my flat lap grinder (so it's effectively about a 400) to get rid of any of the saw blade ridges I can see in some of your photos before I refire. Or I use hand pads to smooth them and remove the ridges from the saw blade. The saw blades just leave too many ridges for gunk to get trapped.

Of course, then you need to clean any pinholes of accumulated gunk from the grinding. I use a garden hose sprayer on the "flat" setting that gives a thin fan like spray of water to clean the pinholes. But I live in Arizona, where I can do this outside 11 months out of the year.
Ed Giebel
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