graybeard Posted March 7, 2016 Report Share Posted March 7, 2016 I want to bisk fire some thin, flat sheets of green ware. (Think VERY thin tiles) Can I stack the sheets 5 or 6 high, or am I asking for trouble? Thanks fer yer time! Graybeard Link to comment Share on other sites More sharing options...
LeeU Posted March 8, 2016 Report Share Posted March 8, 2016 I have better success using tile holders that set them upright (vertical) rather than lying flat. I do some very thin sheets this way. Link to comment Share on other sites More sharing options...
glazenerd Posted March 8, 2016 Report Share Posted March 8, 2016 Graybeard: The big issue in firing tile, or large flat sheets of greenware is a mechanical issue: drag/friction. When firing pots, only a small portion of the foot is making contact with the shelf. When firing tiles, the entire surface is in contact with the shelf. The additional weight of stacking them also means additional drag on the shelf. This is particularly important when going through the quartz inversion phase of the firing. The clay is beginning to shrink a little, and going through a phase of permanent change. I do not recommend you stack them, can almost guarantee you will split them. Also, program an inversion ramp at 1000F to 1100F at 100F an hour. This will prevent any micro-fissures from forming; which make themselves known when you glaze fire. I took tile setters and sawed them in half with a wet saw: this allows me to place them in rows and stack tile on edge instead of flat. If you do this type of firing alot then it is worth doing, if not- not worth it. Nerd Link to comment Share on other sites More sharing options...
Chris Campbell Posted March 8, 2016 Report Share Posted March 8, 2016 An important bit of info is missing ... What kind of clay? Some people fire thin tiles vertically for bisque ... I have fired porcelain tiles to Cone 9 on edges with few problems. I rest them against shorter kiln posts so they are straight as they fire. Link to comment Share on other sites More sharing options...
graybeard Posted March 8, 2016 Author Report Share Posted March 8, 2016 I should have added the type of clay! It's a low fire ^04 buff clay--ART clay 105 I believe thanks fer your thoughts Graybeard Link to comment Share on other sites More sharing options...
Benzine Posted March 8, 2016 Report Share Posted March 8, 2016 I've stacked flatter relief sculptures three to four high. But I wouldn't go any higher than that. But in that case, it's because I'm worried about the weight damaging the lower sculptures, as they aren't perfectly flat and could be putting pressure on the bottom ones, in unknown ways. As others have said, you don't want to stack them too high because of the friction they'll generate as each expands and contracts. Since you are firing low, warping isn't really an issue. So you could put stilts in between ever couple. This would allow air flow and reduce the issue with expansion and contraction, that stacking them directly would create. Link to comment Share on other sites More sharing options...
graybeard Posted March 9, 2016 Author Report Share Posted March 9, 2016 Thank's to all fer the replys. I'll let you know how it works out. Graybeard Link to comment Share on other sites More sharing options...
hollyscarlo Posted March 20, 2016 Report Share Posted March 20, 2016 We currently have the hand prints of a young girl that is dying of brain cancer, I want to do everything I can to assure her prints are done and no explosions!!! So please help us out here. We have been firing plaques made from the clay lady clay. I know very little and we are learning trial and error I read on a forum here (which I can't find now) that you should not stilt greenware. We have, but we have also had things explode in there and don't know why. Any help at all would be great. Holly Link to comment Share on other sites More sharing options...
Benzine Posted March 21, 2016 Report Share Posted March 21, 2016 Holly, The only problem, that I can see with stiltting greenware, is that it puts pressure in a small area, as stilts generally come to a point. As long as you are careful, this shouldn't be an issue. Another solution, would be to use kiln posts, on their sides, and set the plaques with one on each end, or even a third in the middle. Lastly, you could use clay coils, made from the same clay as your plaques. Set the plaques on the coils, which allows air flow around the plaque, while still allowing for the expansion and contraction of the clay/ ceramic. Not matter what you do, just make sure the wares are completely air dried. To further insure success, do a slow firing schedule, preferably with a "Candling" at the beginning. Candling is where you have the kiln hold at a low temperature (200 F or so, but a bit under 212 F, so the water doesn't turn to steam causing explosions). If the clay feels cold to the touch, it probably isn't fully dry. Best of luck! Link to comment Share on other sites More sharing options...
Pres Posted March 21, 2016 Report Share Posted March 21, 2016 When I fired anything in the way of tiles, large thin slabs, or bar relief sculptures, I would put a little grog or sand down, and dust it around even with a very course brush so that it was evenly dispersed on the kiln shelf. Then lay the slabs down and then sprinkle some more grog on and stack a second layer, go up about 5 layers this way, put on another shelf set up and continue up. best, Pres Link to comment Share on other sites More sharing options...
graybeard Posted March 23, 2016 Author Report Share Posted March 23, 2016 Thanks Pres, I really like that idea! tom Link to comment Share on other sites More sharing options...
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