Devit, cracked mold & slip-slidin' away

[daffodildeb]

I've got three questions for you learned folks:

1. When you do a fusing of stained glass scraps (same COE, of course), using a wire grid, do you use something to prevent devit? If so, what's the best way to do this? Can you just dunk all the pieces into Borax and water or Spray A? Or do you have a better way?

2. I opened the kiln the other day to find a small crack in a slumping mold. It's a shallow bowl/salad plate, and the crack extends from the edge to the center. Is it a lost cause, or can the bisque be repaired? If not, is it likely to split totally the next time used, or can it be used indefinitely? The widest part of the crack is about .5mm.

3. What can I do to prevent pieces from shifting in the heat??? I use white glue to get it into position until it's on the kiln shelf, but of course that burns off fairly quickly. I'm trying to make some dichro pendants that look great except that one edge where the top layer of clear shifted during the fuse

Okay, that's more than 3. Start charging me...

[Brian and Jenny Blanthorn]

I've got three questions for you learned folks:

1. When you do a fusing of stained glass scraps (same COE, of course), using a wire grid, do you use something to prevent devit? If so, what's the best way to do this? Can you just dunk all the pieces into Borax and water or Spray A? Or do you have a better way?

Well I still learning

Devit if U realy wanna know about it have a look in the archives I occasionaly put up a bit as do my golobal research labs

If U get flux on the shelf it will eat it

Whats the wire grid ??

Is that a dam ?

Brian

[Barbara Muth]

I'll say something about #1 and #3.

I would assume that after you get the glass that went through the grid, you will cut it up and use the elements in other work. Sandblast it clean and worry about the devit in the final firing. That's what I would do, anyway.

any adhesive I know of will burn off long before the glass is hot enough to stick. Two things you can try are to:
1. think about how gravity may pull pieces once the glue is burnt off, and lay up accordingly.
2. go slow.

going slow is hard for those of us (ahem) who are impatient types. But I am learning that it is worth it in the long run.

Barbara

[Leslie Ihde]

you may be able to repair your bisqued mold with paper clay. Obtain some from Axner (axner.com)- a small sample amount and ask that he send the information sheet with it. dampen your bisqued mold, apply paper clay, dry, and repeat, until you have well filled your crack. sand and refire mold. it sometimes works.

Leslie

[jerry flanary]

What about filling the crack w/ kilnwash? Several applications over a day or two?
j.

[daffodildeb]

Okay, here goes:

Brian, here's the reference to what I was talking about:

http://www.ramoreydesign.com/shelfmelt.html

Barbara, I don't have sandblasting equipment, so I still have a problem. What happens to the devit in the final firing if it starts with devit??
Can I just put a devit spray on the pieces and do the frame melt?

How slow is slow? I don't have a controller, so I'm finding it hard to be very precise. I am planning to get another kiln, so when I do have the controller, how many degrees per minute would you recommend?

I'm hoping Tom in Texas will chime in here about using kilnwash or anything else to repair bisque molds. Wouldn't it serve to drive a wedge in the crack to make it worse? Tom, are you online?

[Brian and Jenny Blanthorn]

Okay, here goes:

Brian, here's the reference to what I was talking about:

http://www.ramoreydesign.com/shelfmelt.html

Barbara, I don't have sandblasting equipment, so I still have a problem. What happens to the devit in the final firing if it starts with devit??
Can I just put a devit spray on the pieces and do the frame melt?

How slow is slow? I don't have a controller, so I'm finding it hard to be very precise. I am planning to get another kiln, so when I do have the controller, how many degrees per minute would you recommend?

I'm hoping Tom in Texas will chime in here about using kilnwash or anything else to repair bisque molds. Wouldn't it serve to drive a wedge in the crack to make it worse? Tom, are you online?

In this case anti devit stuff will poss stick 2 kiln shelf

So if U do use it then use a lot of wash n B prepaired 2 remove it from the back

As 2 ur mould U might just try china clay

Wet mould first then get some in the joint wet

Or could try morter 4 the kiln

Brian

[Tom White]

Sorry I'm a bit late tonight but the shop is open 'til 9 pm Tuesday and Thursday. Cracks are among the most difficult to mend in ceramic items. About the best method I have seen is to drill a small hole at the end of the crack nearest the center of the item to reduce or spread the stress that caused the crack. Then use a ceramic mender material to fill the hole and the crack. Apply, work into hole and crack, allow to dry, sand smooth, repeat if necessary, fire to mature mender. Some like to widen the crack with a small carbide cutter before applying mender to provide a larger surface for the mender. My favorite mender is "Marx Magic Mender" available at many ceramic studios.

Best wishes,
Tom in Texas