throwing some pots

Jessf

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I plan on throwing my own pots on the wheel, looking for some suggestions and/or things to look out for. I'm using a cone 6 clay, is that appropriate for winter climates?

secondly, I was thinking about the technique one might use to make an oval pot on the wheel and the only thing I can think of it to throw a round pot, then cut out a small section in the middle and squash the pot on two sides, making an oval.

Is there any other method to throwing an oval pot?

I can do slab construction for the square pots and perhaps ovals as well.

how thick should the bottom and sides be?

I'm going to be throwing some large pots, 16"+ on the minor dimension and probably closer to 22" on the major dimension.

Is there a golden rule with regards to pot length vs depth?

thanks
 

rock

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I plan on throwing my own pots on the wheel, looking for some suggestions and/or things to look out for. I'm using a cone 6 clay, is that appropriate for winter climates?
UH HUH, IF YOU FIRE TO CONE 6

secondly, I was thinking about the technique one might use to make an oval pot on the wheel and the only thing I can think of it to throw a round pot, then cut out a small section in the middle and squash the pot on two sides, making an oval.
COOL, THATS A GOOD ONE, SEAL AND CONSOLIDATE THE CUTOUT WELL OR CRACKS WILL EXTEND FROM THE ENDS. AFTER A GOOD BURNISHING ..THEN CUT HOLES FOR DRAINAGE

Is there any other method to throwing an oval pot?
YES,SEVERAL... UTUBEIT


I can do slab construction for the square pots and perhaps ovals as well.
GREAT

how thick should the bottom and sides be?
TRY FOR 5/16-3/8"... BIGGER POT SLIGHTLY THICKER

I'm going to be throwing some large pots, 16"+ on the minor dimension and probably closer to 22" on the major dimension.
NICE

Is there a golden rule with regards to pot length vs depth?
YES ITS CALLED THE GOLDEN RULE, BUT I LIKE TO GO SLIGHTLY LARGER ON THE SMALLER DIMENSION

GOOD LUCK
 

rockm

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I'm not a potter, but have picked up a few things about bonsai pots over the years. Sorry if I sound like a curmudgeon...

Cone 6 ain't gonna cut it if you're living in USDA growing Zone 7 or lower that get temperatures below freezing for months on end. Cone 8 and 9 produce entirely frost proof containers...

Also, the larger the pot, the more problems it will most likely have with drainage when it's finished. Most beginners never put adequate drainage holes in larger pots. Bigger holes work best, not a lot of little holes. Large pots wrack and warp as they're made. An irregular, sloped or slumped pot bottom can kill a tree by screwing up the drainage...

FWIW, if you're selling larger pots, round is NOT a great, versatile shape (for any bonsai pot, really). The A 22" round pot is a lot of pot that probably would spend a long time finding the right bonsai... Oval is good, rectangles too. Squares not so much.

If you're selling "serious" bonsai pots, stay away from "arty" shapes and flashy glazes at first.

Bonsai pots can't "shout" if they're to actually be used.

Oh, and applying strict mathematical formulae to bonsai can result in really bad bonsai with no natural "spark." It's nice to think you can apply such equations and produce a masterpiece. Won't happen...
 
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Jessf

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thanks for the help guys. I'll see if I can get over to the community centre this weekend and rustle up some pot(s).

By round I meant the minor and major axes. The pot will be an oval with a large dimension of 22 and a small dimension of 16.
 
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Jessf

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just did some quick calculations. If I want a pot that's 12" by 20" when fired, I need to make a round pot with the same circumference as my desired oval, 50". I need to account for 10% shrinkage, so the pre-fired size of the oval needs to be 13.2" x 22", or a circumference of 55". So if C=(3.14)d then the diameter of the pre-fired round pot needs to be 17.5".

we'll see if any of this has any validity when I'm done.
 

biglou13

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unless your well experienced with specific clay, and same batch, and conditions i wouldn't count on exact dimensions.

your community center may have limitations on max size of pieces.

it sounds like your new to pottery? if so id concentrate on wedging then pulling cylinder and bowl techniques.

im also with rockm. best pieces are hand/head to clay. no rule(rs) involved.
 

Jessf

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I've filled the top two shelves in my kitchen with bowls of various sizes and one water jug. By no means a seasoned veteran, but I'm beyond wedging and centering.
 

rockm

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Everyone has to start somewhere, but forgive me, but this will sound bad, but bonsai pots aren't kitchen bowls or serving containers. They are a lot more. I've seen a few potters that consider them nothing more than a casserole dish with holes in the bottom--and their work looks like a casserole dish with holes in the bottom...

Really good bonsai potters have acquired not only an understanding of how to work clay, but also an intricate understanding of the aesthetics a pot requires coupled with some knowledge of horticulture (even a beautifully made pot can wind up killing the tree that's in it if it's not constructed and fired properly).

BTW, one very famous American bonsai potter gave up and went back to making dinnerware because he became frustrated with the constraints of bonsai pot making. It can demand discipline that some potters find too constrictive.
 

Jessf

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"even a beautifully made pot can wind up killing the tree that's in it if it's not constructed and fired properly"

this is the bonsai specific information I'm looking for. How can an improperly made pot kill a tree? So far I've read poor drainage can be an issue. What about soil depth? Does soil depth depend on the tree type, root system, volume of soil in general, climate?

What about glazes and washes? Would a complete iron wash potentially leach iron into the soil?
 

rockm

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"How can an improperly made pot kill a tree?"

Warped bottoms, improper drain holes (too small, wrongly placed), pot bottoms that sag allowing water to collect in constant puddle underneath the soil can all kill a tree. This is an issue for larger pots in particular.

Shallow pots, even sideless slabs can be used for bonsai. That's not really your concern, though. It's up to the bonsaist to know what tree can handle shallow pots and slabs. Shallow pots are usually used to convey a panoramic setting.

Climate can make a difference for pots. Unglazed, low fired pots can be used successfully, but only in tropical areas that don't get frost.

Frost resistance can be a big deal for bonsai pots. Even "quality" imported bonsai pots can break, delaminate and crack in winter conditions. Incurved pot rims can contribute to even cone 8 or 9 pots breaking in freezing weather, as the freezing root mass expands but is blocked by an overhanging rim.

Glazes shouldn't go inside the pot. This was thought years ago to contribute to root problems because it prevented pots from "breathing." That's not really true. Horticulturally, tree roots needs something to "grip" on the pot interior. Glazes cover up the roughness of the fired clay that allows roots to get a purchase on the interior walls of the pot.

Iron washes are used all the time for bonsai pots. Not using anything on the interior also avoids glazes leaching into the roots, but I really don't think that's much of an issue.
 

Jessf

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I was able to throw a low pot that was the diameter of the wheel it self, which is 13" if I recall. The problem was making it an oval at that size. Removing a pot of this size directly from the wheel would not work, so I through it on a batton with the intent of just lifting the batton off the wheel. Well, once I had my 13 inch dish I cut out the "leaf" from the middle so I could bring the two halves together, so far so good. I wanted to release the piece from the batton so it would slide together but as I pulled the wire beneath the clay the middle portion of the wire tracked up and through the middle of a piece. I guess for something this large I need to really hold the wire tight, like two people pulling from both ends tight. With more practice I'm sure this method is possible, but I'm only able to make a dish 13" in diameter, which when turned into an oval won't get me my final dimensions, if you recall I need a 17.5 dish to start with.

I think for this first large pot I'll do slab construction. But anything from 1" to 9" in diameter I think is within my ability to throw and remove.
 

Jessf

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that is so cool. I would have never thought to do it that way. I'll see if i can get my hands on a larger bat. But for now I think I'll focus on slab forming my first pot. The technical info on Lang's website is great.
 
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Yeah, Ron is not only a great potter, but a great guy as well. His wife(whose name escapes me for the moment) makes marvelous small pots as well. Mark, while I agree with your words about shape and drainage in theory, Ive never heard of such a thing in practice. I have several planted Kurama stones that I tip for drainage, and a Couple of Hobby potters pots with dips and uneven bases that I tip for drainage...an experienced bonsaist should easily identify these flaws and compensate, if the pots worth it! So don't be too discouraged by base dips and beginners flaws Jess, pottery is a fluid art transmuted by fire, sometimes the flaws, crafted by flame, are the very things that raise them to the level of fine art.
Ryan
http://japanesepots.wordpress.com/
 

rockm

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"Mark, while I agree with your words about shape and drainage in theory, Ive never heard of such a thing in practice."

I have run across several pots in the last 15 years that have repeatedly caused problems for the trees in them. They have had inadadequate drainage holes, or places that collect water where a drainage hole should be. The exact cause of some problems are a mystery, since the trees in them have been healthy going in and unhealthy after remaining in them for a year or so. Has happened repeatedly for the same container. Once the trees were removed and placed in another container, they have done fine. Can't say exactly that it's the container's construction, but there is certainly something going on with it.
 
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Interesting to note Mark. I know that many older pots are NOT conducive to the long term health of trees, some have downright poison compounds in the clay that leaches out over time. Overly porous bodies can also harbor fungus. I think for me I've never seen such issues maybe due to poor construction because I tip constantly after watering to see how drainage is going(and because I use well made, mostly Japanese pots!)
Ryan
http://japanesepots.wordpress.com/
 

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