Slab thickness based on pot size?

darrellw

A question for the more experienced potters. What slab thickness do you generally use for various pots sizes?

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Boondock

(I'm not an expert), but I have noticed something since I started making pots using slabs.

Visual proportion, where there is a harmonious relation between the various parts, when viewed as a whole can be an important aspect. I've found that the thickness of the walls of the pot carries alot more "visual weight" on very simple designs. In other words, the more simple the design, the thicker the walls.

The addition of a lip or rim plays a trick on the eye, and makes the pot walls look heavier (or shorter in height). Also the "shadow line" that a rim (either on the top, middle or bottom) adds to this phenomena.

Here are pictures of two pots I've recently made, they are both about 10 inches. The dark brown pot with the rim is made of slabs 3/8 inch thick. The applied rim (and the shadow it produces) makes it appear heavier. The other pot (lighter color and not yet fired, next in line for my on-going slip-glaze experiments) is the same size, simpler in design, but the walls of the pot are 1/2 inch thick.

I know you are probably looking for something like this...

7 inches or less = 1/4 inch
7-12 inches = 3/8 inch
12-20 inches = 1/2 inch

But the way I would answer this is to use the thickest walls you can get away with and still maintain visual proportions and functionality.

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darrellw

Hi Boondock,

I agree with everything you say regarding the "artistic" aspects. What I was wondering was more around functional/practical aspects. I recently made my first slab pot, a 17" round monster which I intended to then modify on the wheel (that is another story). Anyway, the slabs were 1/4" thick, and so far that seems to be OK, but the pot is certainly lighter that one would expect for something of this size (I had intended to add some extrusions that would have added a lot more visual and some structural weight). So I'm more concerned about the minimum durable thickness.

-Darrell

muddslinger

Hi Darrell,

That would depend on the type of clay you're using. For a pot that size, I would go a little thicker, maybe 3/8".
Best,
Kevin

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morea

Dear Darrell

Looking at the pics , i wondered why you made it so thick ?

For wheelthrowing the clay is more poor with grog
so easier to deform , the clay tension keeps it steady
and the dry-ing should be smooth .

For slab building , the clay has the bigger grog , the little stones.
This clay has normaly a good 'stand' , keeps the form excelent
with smooth dry-ing !!

Kind regards
Morea

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Boondock

The lighter colored pot (that I used as an example above) is now fired using my slip glaze. It is constructed with 1/2 inch walls

Yes it does look chunky for a pot this size.

Attached Images

Boondock_pot_32.jpg (46.5 KB, 39 views)

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Boondock

here's another pot i made with 1/2 inch walls

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pot35.jpg (42.9 KB, 41 views)

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stonemonkey

Boondock

For the pot you have shown in the last reply 1/2" seems a little excessive, IMHO. I only use 1/2" thick slabs for pots that are over 12" in length, using 1/2" slabs on pots under this size seems too heavy on the eye.
When I make shohin pots I use 3/8" or 2/8" slabs this, for me, is a nice proportion.
Don't get me wrong there is no right way, I look at what the tree demands. If the Bonsai is delicate and feminine then a thin delicate pot is appropriate. If the Bonsai is powerful and masculine then the pot should reflect this. I find dsing this approach achieves a union between the tree and the pot.

Hope this helps

Regards

Andy

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darrellw

Hi Andy,

Thanks for this, so my 1/4" thick, 18" pot is definately on the thin side....

-Darrell