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nrsmdwf

Tile warping in glaze fire

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nrsmdwf    0

New to forum! Thoroughly enjoying the site, gallery and forum. My mind is swirling with wonderful ideas!

 

Wondering if anyone has a suggestion as to why my 4 inch tiles are warping in the glaze fire? (cone 5-6)

 

I have already done the following: use groggy clay (Std 240G), carefully slab-roll (double roller) to 3/8 inch thickness, compress slab with rib, use care to not bend or drape slabs when moving, cut tiles when slab is firmed, dry between two pieces of sheet rock, flip tiles over partway through drying, dry slowly (4-6 weeks in a crawl space South Carolina basement!).

 

Tiles are essentially flat when dry, Bisque fire to 06 and remain flat. Cone 6, various glazes, sprayed. I lose over half of the tiles to significant warping in the glaze fire.

 

Help?

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bciskepottery    925

Might be the clay body . . . 240G has fine grog; might need something with medium to coarse. May not be a good handbuilding body. Also, consider firing on top of cookies or coils to raise the tiles above the kiln shelf.

 

240.jpg

c/6 Ox.

240G WHITE CLAY WITH GROG(Cone 6) A very smooth, plastic throwing body with fine grog.

Shrinkage: 12.5% at C/6.

Absorption: 2.75% at C/6

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Chris Campbell    1,088

No one ever believes this but here goes ....

Moving, touching and manipulating tiles warps them ... Good old clay memory at work.

Factories roll those tiles flat from start to finish and no one touches them! They stay FLAT the whole time.

 

Easy solution ...

Make your slab, cut your tiles, slide them horizontally onto a paper covered board.

Drop that board from waist height to the floor twice then leave them alone til they are dry.

You can put these tiles outside in full sunlight to dry and they will not warp ... Unless you jiggle them to test them, or lift them to see if they are dry or move them to another surface or do some other poking thing,

Honest! You don't need wall board or fancy flipping or weeks of patience ... You just have to stop messing with them. :D

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nrsmdwf    0

No one ever believes this but here goes ....

Moving, touching and manipulating tiles warps them ... Good old clay memory at work.

Factories roll those tiles flat from start to finish and no one touches them! They stay FLAT the whole time.

 

Easy solution ...

Make your slab, cut your tiles, slide them horizontally onto a paper covered board.

Drop that board from waist height to the floor twice then leave them alone til they are dry.

You can put these tiles outside in full sunlight to dry and they will not warp ... Unless you jiggle them to test them, or lift them to see if they are dry or move them to another surface or do some other poking thing,

Honest! You don't need wall board or fancy flipping or weeks of patience ... You just have to stop messing with them. biggrin.gif

 

You're right! Don't believe it! But I'm going to try it anyway! Thanks.

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Chris Campbell    1,088

I was told about this method ten or so years ago by Elizabeth Priddy and could not believe it either ... I have made hundreds and hundreds of them in all shapes and sizes. It really sounds too simple to work doesn't it?

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Marcia Selsor    1,301

I agree that it could be the clay as well since it is a throwing clay body. You don't say how you are firing them. Are you using tile setters? Are you using any type of support to get them off the shelf and heated all around?

 

Marcia.

 

 

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No one ever believes this but here goes ....

Moving, touching and manipulating tiles warps them ... Good old clay memory at work.

Factories roll those tiles flat from start to finish and no one touches them! They stay FLAT the whole time.

 

Easy solution ...

Make your slab, cut your tiles, slide them horizontally onto a paper covered board.

Drop that board from waist height to the floor twice then leave them alone til they are dry.

You can put these tiles outside in full sunlight to dry and they will not warp ... Unless you jiggle them to test them, or lift them to see if they are dry or move them to another surface or do some other poking thing,

Honest! You don't need wall board or fancy flipping or weeks of patience ... You just have to stop messing with them. :D/>/>

 

 

I want to try this, as it makes perfect sense. It sounds like I would need to cut and carve, or whatever I am doing to the tiles, and then drop them. Assuming I am able to drop them so that the board they are on falls flat, will dropping the tiles distort their shape?

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Chris Campbell    1,088

No one ever believes this but here goes ....

Moving, touching and manipulating tiles warps them ... Good old clay memory at work.

Factories roll those tiles flat from start to finish and no one touches them! They stay FLAT the whole time.

 

Easy solution ...

Make your slab, cut your tiles, slide them horizontally onto a paper covered board.

Drop that board from waist height to the floor twice then leave them alone til they are dry.

You can put these tiles outside in full sunlight to dry and they will not warp ... Unless you jiggle them to test them, or lift them to see if they are dry or move them to another surface or do some other poking thing,

Honest! You don't need wall board or fancy flipping or weeks of patience ... You just have to stop messing with them. :D/>/>/>

 

 

I want to try this, as it makes perfect sense. It sounds like I would need to cut and carve, or whatever I am doing to the tiles, and then drop them. Assuming I am able to drop them so that the board they are on falls flat, will dropping the tiles distort their shape?

 

 

Depends on how soft the clay is. Fairly firm clays stay put but I imagine really soft ones would move.

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Idaho Potter    62

I have another question for you Chris. If I made tiles (either 8" or 12") and wanted to make some sculptural additions, do I drop the tiles first then add extra clay? I have a project I want to start, but the additions may extend out as much as 4" and I'm afraid dropping would ruin that aspect. Any help greatly appreciated.

 

Shirley

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nrsmdwf    0

I agree that it could be the clay as well since it is a throwing clay body. You don't say how you are firing them. Are you using tile setters? Are you using any type of support to get them off the shelf and heated all around?

 

Marcia.

 

 

 

No, the only thing I have tried is grog or sand on the kiln shelf to aid in movement during the fire. I'm trying to do a fair volume of tiles - like 30-40 per order (that's 2-3 firings in my small kiln), so would need to look at something that would not take too much space. Not sure what "tile setters" are... will have to investigate ...

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nrsmdwf    0

No one ever believes this but here goes ....

Moving, touching and manipulating tiles warps them ... Good old clay memory at work.

Factories roll those tiles flat from start to finish and no one touches them! They stay FLAT the whole time.

 

Easy solution ...

Make your slab, cut your tiles, slide them horizontally onto a paper covered board.

Drop that board from waist height to the floor twice then leave them alone til they are dry.

You can put these tiles outside in full sunlight to dry and they will not warp ... Unless you jiggle them to test them, or lift them to see if they are dry or move them to another surface or do some other poking thing,

Honest! You don't need wall board or fancy flipping or weeks of patience ... You just have to stop messing with them. biggrin.gif/>/>/>

 

 

I want to try this, as it makes perfect sense. It sounds like I would need to cut and carve, or whatever I am doing to the tiles, and then drop them. Assuming I am able to drop them so that the board they are on falls flat, will dropping the tiles distort their shape?

 

 

Depends on how soft the clay is. Fairly firm clays stay put but I imagine really soft ones would move.

 

 

... and when would you do any cut-outs on the backs of the tiles? I cut out hanger holes or deep scored lines for mounting .....

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nrsmdwf    0

I just looked up a tile setter - really looks like it would SAVE kiln space! Seems the tiles would slump in the middle - but I guess they don't. Any pointers on using these?

post-18444-135320725891_thumb.jpg

post-18444-135320725891_thumb.jpg

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Chris Campbell    1,088

Answers to the drop method ...

 

The key is not to move them, lift them, torque them etc ... if these additions can be made without moving the tile at all you should be ok ... if you need to move the tile you should slide it sideways without lifting. I would put the tile on a piece of paper before so you could move it by pulling the paper not lifting the tile.

 

As to cut outs ... These can be cleanly and easily done when the tile is leather / cheese hard ... When the whole tile is firm and hard not just sort of.

 

I usually fire them standing on end in a line since none of my shelves are level anymore and the tile setter is usually under a ton of other stuff.

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bciskepottery    925

Are your tiles for functional or decorative use? Is a vitrified body needed for their use? Rather than firing to cone 5/6, you might want to consider a lower temperature clay or firing the current clay body to a lower temperature . . . especially if the tiles are for decorative purpose. A lower temperature firing might reduce warping.

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muddylane    0

I make small tiles (5 cm sq). I roll out a sheet of clay, mark out the clay into as many tiles will fit on it, and i do not cut thro' the clay - i cut about 1/3 of the way thro, and let the tiles dry, in a whole sheet. When the clay is quite hard, i just snap them apart (gently). Because all the corners of each tile were joined to each other, during the drying process, they cannot lift up. But, i am going to try Chris's method with larger tiles

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Marcia Selsor    1,301

I agree with Chris about not lifting the tiles but also consider your clay body which is a throwing body. You should consider a handbuilding bod, one with more grog or a raku body in my opinion. I use those type of tile setters and my tiles do not warp at ^6. They are about 3/8" also. If they still warp after the drop method, change clays.

 

 

 

Marciia

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nrsmdwf    0

You guys are great! Thanks for all the good ideas and tips. I am going to try suspending one of my currently drying tiles (240G) on two kiln posts to see if it slumps, so I should know if the tile setter will work for that clay (I really like the idea of that thing!). Then, I'll definitely try a coarser grog clay and the drop method. I'll try to remember to post my results for anyone else who might be looking at this! Thanks again everyone!! :)src="http://ceramicartsdaily.org/community/public/style_emoticons/default/smile.gif">

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nrsmdwf    0

Are your tiles for functional or decorative use? Is a vitrified body needed for their use? Rather than firing to cone 5/6, you might want to consider a lower temperature clay or firing the current clay body to a lower temperature . . . especially if the tiles are for decorative purpose. A lower temperature firing might reduce warping.

 

 

Thanks. I'd thought of that, too, but hadn't found any lower temp clays/glazes I liked. I think I prefer not to go to the earthenware temps ( I just like the stoneware "look"), but may end up there anyway, if these other ideas don't provide the solution.

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Kabe    7

I do tile work and seldom have warpage but I mix my own clay and use a lot of grog. Let me ask this as a question because I might be way off base here. Could it be that the glaze is to tight and instead of crazing you are getting shivering. Seeing that it is a flat tile and not a circular surface maybe the edges are pulled up by the difference in thermal expansion. I know that shivering can tear a pot apart. I have a glaze that will break a porcelain pot everytime I try it. I do not know what glazes you are using or if all your tiles warp or just certain ones. Maybe someone who is better informed could tell if this is possible. Happy firing

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Kabe    7

Kabe, You are correct that glaze tension can cause warping. The coefficient of expansion and contraction is a factor in this.

 

Marcia

 

 

Hi Marcia. A friend of mine said someone in one of his college classes made some tile and when they were fire the tile "cupped" I guess that would be the word. They were like upside down bowls. I thought about this abit last night and maybe that would be more like a situation where if the glaze was on a pot it might of shivered and if thetile warped the oppisite way and the edges all pulled up it would be like crazing. It would be interesting to manipulate a glaze both directions and apply the test glazes to thin tiles and observe the effects. happy firing

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nrsmdwf    0

I do tile work and seldom have warpage but I mix my own clay and use a lot of grog. Let me ask this as a question because I might be way off base here. Could it be that the glaze is to tight and instead of crazing you are getting shivering. Seeing that it is a flat tile and not a circular surface maybe the edges are pulled up by the difference in thermal expansion. I know that shivering can tear a pot apart. I have a glaze that will break a porcelain pot everytime I try it. I do not know what glazes you are using or if all your tiles warp or just certain ones. Maybe someone who is better informed could tell if this is possible. Happy firing

 

 

Thanks for that idea. I'd actually thought of that, but the warping does not seem to be consistent between tiles (some arch up, some get wavy, a few stay flat, etc.) and it seems to happen with several different glazes (I'm using commercial Cone 5-6 glazes: Laguna, Spectrum). Have tested several suggestions regarding handling and "dropping on the floor" =) and that lot of tiles is drying. I will definitely be looking at a groggier clay for the next batch.

 

How thick and what size do you make your tiles, and how do you dry them?

 

Thanks for all this great info!

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nrsmdwf    0

An update on results of several ideas presented here, and others - :

 

1. Changed to a heavily grogged clay, Std 420 and Std 547 (red). The 547 seems pretty good, but have not found a glaze that looks decent on 420. Amazing shades of ugly so far. Don't like the huge sand particles, tricky to smooth edges and backs or cut hanger-hole at just the right time in the drying process when still damp enough to smooth, but firm enough to move. Really would prefer a less coarse grog.

 

2. Made sure when rolling out clay to have minimal movement under the fabric I was using (bedsheet cotton). I believe the surface fibers of clay were adhering to the fabric while the deeper layers were getting rolled unevenly. I'm now beginning with a slab not much thicker (1/4") than the desired thickness (3/8"), roll out, pull fabric away and flip slab/roll a couple of times so there is no 'drag' on the surface from the fabric. Using dowels for thickness guides and kitchen rolling pin. Will consider going to a local studio to use the slab roller again if I have a big order.

 

3. Moving, flipping slab by sliding a piece of luan plywood under the fabric and turning without distorting the slab.

 

4. Drying on an open wire rack with no plastic or covering. Even leaving wet tiles on the damp sheeting on the wire rack influences drying/warping.

 

5. The drop method suggested was not useful, at least not with wet clay. The edges slumped making an uneven thickness between center and edges of tile. Did not try after clay had firmed up a little.

 

6. Changed to a pizza cutter instead of fettling knife. Less distortion and drag on wet clay when cutting out tiles.

 

7. Tried the 'score and break apart later' method, which worked very nicely, but with the heavy grog in the clay it was too difficult to smooth the edges once dry.

 

8. Firing on tile racks (large size to accommodate larger thickness), and found a sale on them!

 

As a result of these changes (and I believe primarily #1, 2 and 4), I have only 10-15% warping, vs >60%. Better, but I still do not like the clay bodies (too gritty), and have not found a good glaze for 420. Hopefully someone can benefit from my results, and suggestions are always welcome! Thanks so much to this most generous community of artists!

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