mrcasey
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Posts posted by mrcasey
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I appreciate your reply and agree with you, but do the manufacturers state anywhere that this is ok?
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Can rectangular kiln posts be laid on their sides? They don't really come with instructions and I don't know if the manufacturers specify.
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Is there any evidence that raku pieces need to be thicker than normal cone 6 functional ware? Several folks in our studio suggested that raku pieces should be a bit thicker to withstand the thermally violent process of the firing and quick cooling. I guess I'm thinking of normal functional ware as being 3/16" to 5/16".
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2 hours ago, Mark C. said:
I have a few ideas
clay has memory so if you bend those slabs during any part of the making ,drying assembly process you will get bending layer-maybe you are keeping them flat100% and this is a non issue
Are these glazed at all or left bare as glaze on one side will warp the walls
If the bottom is unglazed, place for supports under the Bottom exactly same thickness as feet -they can be loose (not attached )for support as they will shrink the same as the feet while supporting that 14 inch bottom.
Use waster slab as the feet feet/and pot will shrink the the same as slab and not grab the shelve.
14 inch bottom with 4 corner feet is asking for trouble unless you take at least some of the above tips
Some are unglazed. Traditionally, glazed bonsai pots are not glazed on the insides.
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2 hours ago, Pres said:
How many feet do you add to the bottom of this 14" long bonsai pot? Does it have enough support for the length?
best,
Pres
It has the traditional 4 feet. Unless I'm mistaken, the warping seems to be mostly side-to-side.
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2 hours ago, dhPotter said:
How do you flip the slabs while they are drying on the drywall? Do you pick them up with your hands, or use another board of drywall on top to flip them - like a sandwich of drywall with slab in the middle?
sandwich
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18 minutes ago, neilestrick said:
On solution is to put a slight curve in the sides, which makes them less likely to bow inward.
I've considered this and may try it out. Never tried waster slabs.
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I use a slab roller. Clay is rolled out at roughly the softness at which one would throw on the wheel. Slabs are about 1/4" thick. The clay is then placed on sheets of dry wall for about an hour and left to firm up a bit to about leather hard. These slabs get flipped a couple of times so that they dry evenly on top and bottom.
The walls are anywhere from 6" to 14" long. The wall corners are beveled and cut in a trapezoid shape so that the walls angle out slightly from vertical at about 10 degrees. Corners are scored, slipped, and assembled. I use a t square to try to get all corners at 90 degrees with walls straight. There is usually a little bit of a gap (1/16") where the corners meet, and I fill them with a bit of coil.
I score and slip the bottom of the rectangle, score the slab for the pot floor. I use the t square again
before pushing the walls onto the floor. Sometimes, the pot will have a rim; sometimes not. The rims are made in one piece and look like picture frames before being attached. They are scored, slipped, etc. A coil of clay is then placed around the outside join. The clay for
the coil is necessarily softer than the leather hard walls. I use an apple corer to make drainage holes. The pot is flipped
over and feet are attached.The pot is put under plastic and left upside down on drywall for a day to help keep the rim flat and level. The pot is flipped back on its feet so that the feet remain relatively level. After a couple of days, I'll take the plastic off. Sometimes, I will start seeing a bit of rim bowing as the pot dries. Often, one side will remain relatively straight but the other side will suck in a bit. Once the pots is bone dry, I will spray water on a mirror and move the pot back and forth on the mirror to even up the feet.
I don't have any particular place I set these pots in the kiln. I use flat kiln shelves. We fire electric
to cone 6.I have noticed that the thinner the walls and longer the pot, the more warping I see. 14" long rectangles with 1/4" walls have quite a bit of "life" to them. I've noticed that a lot of the expensive Chinese and Japanese antique bonsai pots have some warping. Maybe unless I want to use modern mold methods, I just have to live with it?
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I've been making slab built bonsai pots for a while. One of my biggest issues is dealing
with warping. I now use Laguna #75. I chose it because of its low water absorption and color.1. Can anyone suggest a cone 6 clay body with very low warping and less than 2% water absorption?
2. Are there any articles that explain how to formulate clay bodies to get the properties that I want? I'm happy to buy the raw materials and mix them myself.
3. Could I just add some grog to the #75? If I do, will it increase water absorption?
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This pot was made with white mid-range stone ware: Laguna #65. It was fired once, but some of the glaze crawled, so it was reglazed and fired
again. There was a clean horizontal break all the way around. The pot was slab constructed and the walls are convex.
Does anyone know what might cause this?
Setting Kiln Posts On Sides
in Equipment Use and Repair
Posted
No offense intended - I agree with you. Some folks in our community studio thought it was an issue (which I thought sounded off base), and I just wanted to make sure.