Cutting, devit spray, and other questions - WarmGlass.com

Cutting, devit spray, and other questions

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DrRourke
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Joined: Fri Jan 23, 2015 3:15 pm

Cutting, devit spray, and other questions

Postby DrRourke » Wed Jan 28, 2015 5:38 pm

20150110_113212.jpg


1.I make large (12 inch) plates, every time I score with a wheel and try to break it, the break doesn't go cleanly and it ends up ruining the piece or I have to grind for 30 minutes to make it look clean. Could I use a tile saw on a 12 inch plate while keeping the work area from being drenched with water? The reason I'm cutting is because I'll make something like a mosaic with square tiles and sometimes one or two will leak out a bit and make the edge uneven.

2. I had some cloudy issues on the edges on all the pieces I thought were devit when really I think it was the boron nitride I was using... so I tried brushing devit spray on top of my piece. Still, around the edges I got a fog. It's just that now you can see the fog in the lines of the brush strokes. It didn't show up in the middle though. Am I using too much? Too little? Is devit spray useless? The image is below.

3. On the same striped plate, I got wrinkles around the edges. Is there any way to prevent this? Same with the smaller bowls, it kind of "crinkled" I would say.

4. What could I use to make a flatter surface on the bottom of the plates besides a 500 dollar lapidary wheel?

This was my first project.

David Jenkins
Posts: 174
Joined: Wed Apr 29, 2009 10:35 pm
Location: Cypress, Texas

Re: Cutting, devit spray, and other questions

Postby David Jenkins » Wed Jan 28, 2015 9:39 pm

Does the striped piece consist of single layer strips only? From the edges, it looks almost like it's a single layer, in which case the edges will certainly pull in and create something you probably weren't intending to do.
Dave Jenkins
Glass at Harbor Gates
Cypress, TX

Sharol
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Joined: Sun Mar 05, 2006 2:45 pm
Location: Tennessee

Re: Cutting, devit spray, and other questions

Postby Sharol » Wed Jan 28, 2015 11:38 pm

Can you give us a look at your firing schedules (fusing and slumping)? It's difficult to offer help without them. Also, what type of glass and kiln are you using?

Sharol

Sharol
Posts: 111
Joined: Sun Mar 05, 2006 2:45 pm
Location: Tennessee

Re: Cutting, devit spray, and other questions

Postby Sharol » Wed Jan 28, 2015 11:40 pm

Can you give us a look at your firing schedules (fusing and slumping)? It's difficult to offer help without them. Also, what type of glass and kiln are you using?

Sharol

DonMcClennen
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Joined: Sun Mar 09, 2003 9:09 pm
Location: Ontario

Re: Cutting, devit spray, and other questions

Postby DonMcClennen » Thu Jan 29, 2015 6:20 pm

The pieces you show should be an easy cut with NO grinding required. Get some used window glass (free) and practice your scoring and breaking skills (over and over).. Just enough pressure to get a good one pass score will come easy with some time spent learning (that is assuming your cutter is not dull or damaged). The sound of a good score will become evident.
"The Glassman"

DrRourke
Posts: 5
Joined: Fri Jan 23, 2015 3:15 pm

Re: Cutting, devit spray, and other questions

Postby DrRourke » Fri Jan 30, 2015 3:05 pm

Two layers 3mm: one designed, one clear coat on the top. I only grind when I need to take off a slant from the occasional break on a 3mm non fused piece. But I tried cutting a 6mm piece 12 inches wide and it was a holy disaster. I bought a 7 inch tile saw to tackle these issues. On a different note, I usually use thin kiln paper and it's been curling up over projects. Even when it's weighted down, it tears perfectly around the piece then folds over where-ever it wants to. I tried to remedy this situation by cutting the paper almost exactly to the plate... giving it a quarter inch wiggle room on a 12 inch piece. The paper sucked in, and the piece stuck to the shelf on the very edge. Interestingly, it also cracked at that same place. Thank god I had them shelf mostly covered with boron nitride out of paranoia so it only messed up a small portion. But I'll take the tile saw to that tonight to get the edge off. This is the firing schedule I used for the pieces in the picture.

Fuse:

1. Initial heat
Pre-rapid heat soak 300°F 222°C 1250°F 677°C :30
2. Rapid heat
Process soak 600°F 333°C 1480°F 804°C :10
3. Rapid cool
Anneal soak AFAP* 950°F 482°C :60
4. Anneal cool 150°F 83°C 700°F 371°C :00
5. Final cool AFAP 70°F 21°C :00

Slump:
1. Initial heat
Process soak 300°F 166°C 1180°F 638°C :10-20
2. Rapid cool
Anneal soak AFAP* 950°F 482°C 1:00
3. Anneal cool 100°F 55°C 700°F 371°C :00
4. Final cool AFAP 70°F 21°C :00

Valerie Adams
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Re: Cutting, devit spray, and other questions

Postby Valerie Adams » Fri Jan 30, 2015 3:51 pm

I believe the scummy look on your clear cap is due to using kiln paper. When I started using Tekta as my clear cap, I began having the same issue, but only now and then. Realized it was when I used Thinfire. Now, only using shelf wash, the problem is eliminated. I also vent all of my kilns by leaving the peep hole plugs out.

JestersBaubles
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Re: Cutting, devit spray, and other questions

Postby JestersBaubles » Fri Jan 30, 2015 5:14 pm

If you want to continue to use shelf paper, you might want to try Papyrus. I find it less prone to curling (in fact, I've never had it curl, though I only had issues with ThinFire curling on very small pieces). Make sure you are using *real* ThinFire or Papyrus. There is a cheap alternative that will definitely curl.

Dana W.

DrRourke
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Joined: Fri Jan 23, 2015 3:15 pm

Re: Cutting, devit spray, and other questions

Postby DrRourke » Fri Jan 30, 2015 6:32 pm

This is bullseye thinfire paper but I'm not very happy with it. I have 50 sheets of useless 20 inch wide paper then... wonderful. I suppose I'll learn to use kiln wash. This paper also shrinks an incredible amount, I suppose this is normal but for the price I think it's absurd. I'll vent the kiln and use kiln wash from now on.

Valerie Adams
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Re: Cutting, devit spray, and other questions

Postby Valerie Adams » Fri Jan 30, 2015 6:43 pm

Lots of people use Thinfire and love it. You can easily sell it, I'll bet.

I like to kiln-carve with it. It lends itself to paper punches or easily cuts by hand. You can glue a few sheets together to get deeper carving, or layer multiple cut shapes to get more intricate designs.

I don't have any issues with it other than when I clear cap, in which case, I only use kiln wash.

DonMcClennen
Posts: 356
Joined: Sun Mar 09, 2003 9:09 pm
Location: Ontario

Re: Cutting, devit spray, and other questions

Postby DonMcClennen » Fri Jan 30, 2015 7:51 pm

The old original shelf paper ((15yrs ago) used to curl and shrink...but the more recent formula thinfire (last 10yrs or so) does not shrink or curl. I have a 50 yard roll plus a bunch of the 20" sheets that I've been using for years with excellent results, no curl, no shrinkage, no fog. Maybe you were sold some really old stock...You can easily identify it because it had more texture than present product.
"The Glassman"

DrRourke
Posts: 5
Joined: Fri Jan 23, 2015 3:15 pm

Re: Cutting, devit spray, and other questions

Postby DrRourke » Fri Jan 30, 2015 7:54 pm

Yeah I've been capping in clear so it's very evident. I'll try other colors.

Studiodunn
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Re: Cutting, devit spray, and other questions

Postby Studiodunn » Fri Jan 30, 2015 8:55 pm

Just curious if you vent to 1000 degrees when you use the thinfire? Since you have a good amount of it to use up, that is one strategy that helps the binder burn off and escape the kiln. You can also attempt to burn off the binders and prefire your thinfire. Heat to 1000 and hold for 30 minutes. However, as you can imagine, it will easily be disturbed when you are placing a project(s) on the shelf...But it can be done. A respirator would be essential.

I also like Papyros and have found it holds together for multiple firings better than other products I have used in the past. Kiln wash is my first choice...but sometimes, when crunched for time, I am glad to have fiber paper :)
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- Martin Luther King


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