Vince Pitelka on tue 15 jun 04
This is a technique that I have periodically pushed on Clayart as long as I
have been a member. It is an Early American technique, and I learned it at
Humboldt State in the late 1960s. It is thoroughly explained in my book,
but here's a short course.
Use heavy canvas, and if you can get it, use oilcloth canvas. Cut it into
squares with a diagonal measurement at least twice the diameter of the wares
you are going to make. If you are going to use the canvas squares for a
variety of sizes of wares, make different squares for the different sizes.
The idea is to be able to place as many pieces on a wareboard as you could
if there were no squares beneath them. Rigid bats suck when it comes to
space utilization, unless you are throwing things that are almost the
diameter of the bat.
I tried using a standard fabric seam-sealer along the edges, and it
dissappeared after a few uses and didn't really do any good at all. You can
have someone sew a zig-zag stich around the edge (someone else reported
doing that in another post on this subject), and that should retard fraying.
I never did that. I just pulled off the loose threads when the edge frayed,
and it wasn't much of a problem. I should point that most of my squares are
made from oilcloth canvas, and it doesn't tend to fray much.
I have found that a fine, gritless slurry works best for coating the canvas
and for attaching the squares to the wheelhead. I use Goldart slurry for
buff stoneware bodies, Redart slurry for terracotta bodies, and kaolin
slurry for white stoneware and porcelain bodies.
With a wide brush, completely coat both sides of the fresh canvas squares,
and let them dry completely. You only need to do this the first time. The
residual slurry on the canvas from each use will be enough for the next
time, but always let them dry completely before using them again.
When you are ready to use them, smear a thin spiral of the gritless slurry
out from the center fo the wheelhead. Place your canvas square over the
center, and immediately smear out from the center with a stiff rubber rib,
and start the wheel and smear out from the center in a spiral fashion a few
more times. The excess slurry that comes out from under the bat will seal
the surface of the canvas, and this is important. Use a little more slurry
for this if necessary. If there are any dry areas on the surface of the
canvas, they will absorb water very quickly, and can cause the canvas to
come loose. You will quickly get used to the amount of slurry needed.
The dry slurry on the canvas surface (from coating new squares ahead of
time, or the residual slurry from previous use) absorb the water from the
attachment slurry, and that really makes it cinch down to the wheelhead.
Properly applied, the canvas square will NEVER come loose until you peel it
off or cut it off with a cutoff wire.
Center your clay, throw your pot, and pay special attention to the finish of
the lower edge if you are not planning to wheel-trim. This is an especially
great technique for all those shapes that do not need wheel trimming. When
the pot is done, carefully run the cutoff wire UNDER the canvas, making sure
that it does not snag on the canvas. This is just a matter of care and
practice.
The best device for transfering most shapes from the wheelhead to the
wareboard is a standard diamond-shaped concrete trowel. Go to a flea
market, Big Lots, Walmart, or some place like that, and get the cheapest
diamond-shaped concrete trowel you can find. Get several sizes if they have
them. Don't get any other kind of trowel for this. A wide spatula will not
work as well, because you are balancing the entire weight of the pot above
the level of your hand. The handle on the concrete trowel rises from the
level of the blade, and that lowers the center of gravity, giving you much
more control when transferring pots.
Set the blade of the trowel flat on the wheelhead. Grasp the corner of the
canvas, and drag the pot onto the trowel. Lift it and transfer it to the
wareboard, and drag the pot off onto the board.
If you have finished the lower edge of the pot adequately, then when
soft-leather-hard, all you have to do is peel the canvas off the bottom of
the pot, run your finger around the edge to get rid of the small burr, and
sign your name or stamp your initials or logo.
This is a wonderful system for all small pots, mugs, cups, bowls, pitchers,
covered jars, vases, similar shapes. It is rare that I ever take issue with
anything that Dannon says, but my own opinion is that this system doesn't
work as well for large bowls or plates because the clay shrinks considerably
before you remove the canvas, and this can result in clay memory producing
odd drying/firing warpage in your bowls or plates. However, this probably
depends on the claybody and other variables, and it seems that Dannon has
had good success using the canvas squares for large plates.
I guess that was more than a short course after all.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
Jo Smith on wed 16 jun 04
Thanks for describing this process.. Where do you get oilcloth canvas. Is
it the smelly stuff you used to buy at the 5 and dime for table cloths?
Didn't think it still existed.
Jo
----- Original Message -----
From: "Vince Pitelka"
To:
Sent: Tuesday, June 15, 2004 10:47 PM
Subject: Re: canvas squares as bats
> This is a technique that I have periodically pushed on Clayart as long as
I
> have been a member. It is an Early American technique, and I learned it
at
> Humboldt State in the late 1960s. It is thoroughly explained in my book,
> but here's a short course.
>
> Use heavy canvas, and if you can get it, use oilcloth canvas. Cut it into
> squares with a diagonal measurement at least twice the diameter of the
wares
> you are going to make. If you are going to use the canvas squares for a
> variety of sizes of wares, make different squares for the different sizes.
> The idea is to be able to place as many pieces on a wareboard as you could
> if there were no squares beneath them. Rigid bats suck when it comes to
> space utilization, unless you are throwing things that are almost the
> diameter of the bat.
>
> I tried using a standard fabric seam-sealer along the edges, and it
> dissappeared after a few uses and didn't really do any good at all. You
can
> have someone sew a zig-zag stich around the edge (someone else reported
> doing that in another post on this subject), and that should retard
fraying.
> I never did that. I just pulled off the loose threads when the edge
frayed,
> and it wasn't much of a problem. I should point that most of my squares
are
> made from oilcloth canvas, and it doesn't tend to fray much.
>
> I have found that a fine, gritless slurry works best for coating the
canvas
> and for attaching the squares to the wheelhead. I use Goldart slurry for
> buff stoneware bodies, Redart slurry for terracotta bodies, and kaolin
> slurry for white stoneware and porcelain bodies.
>
> With a wide brush, completely coat both sides of the fresh canvas squares,
> and let them dry completely. You only need to do this the first time.
The
> residual slurry on the canvas from each use will be enough for the next
> time, but always let them dry completely before using them again.
>
> When you are ready to use them, smear a thin spiral of the gritless slurry
> out from the center fo the wheelhead. Place your canvas square over the
> center, and immediately smear out from the center with a stiff rubber rib,
> and start the wheel and smear out from the center in a spiral fashion a
few
> more times. The excess slurry that comes out from under the bat will seal
> the surface of the canvas, and this is important. Use a little more
slurry
> for this if necessary. If there are any dry areas on the surface of the
> canvas, they will absorb water very quickly, and can cause the canvas to
> come loose. You will quickly get used to the amount of slurry needed.
>
> The dry slurry on the canvas surface (from coating new squares ahead of
> time, or the residual slurry from previous use) absorb the water from the
> attachment slurry, and that really makes it cinch down to the wheelhead.
> Properly applied, the canvas square will NEVER come loose until you peel
it
> off or cut it off with a cutoff wire.
>
> Center your clay, throw your pot, and pay special attention to the finish
of
> the lower edge if you are not planning to wheel-trim. This is an
especially
> great technique for all those shapes that do not need wheel trimming.
When
> the pot is done, carefully run the cutoff wire UNDER the canvas, making
sure
> that it does not snag on the canvas. This is just a matter of care and
> practice.
>
> The best device for transfering most shapes from the wheelhead to the
> wareboard is a standard diamond-shaped concrete trowel. Go to a flea
> market, Big Lots, Walmart, or some place like that, and get the cheapest
> diamond-shaped concrete trowel you can find. Get several sizes if they
have
> them. Don't get any other kind of trowel for this. A wide spatula will
not
> work as well, because you are balancing the entire weight of the pot above
> the level of your hand. The handle on the concrete trowel rises from the
> level of the blade, and that lowers the center of gravity, giving you much
> more control when transferring pots.
>
> Set the blade of the trowel flat on the wheelhead. Grasp the corner of
the
> canvas, and drag the pot onto the trowel. Lift it and transfer it to the
> wareboard, and drag the pot off onto the board.
>
> If you have finished the lower edge of the pot adequately, then when
> soft-leather-hard, all you have to do is peel the canvas off the bottom of
> the pot, run your finger around the edge to get rid of the small burr, and
> sign your name or stamp your initials or logo.
>
> This is a wonderful system for all small pots, mugs, cups, bowls,
pitchers,
> covered jars, vases, similar shapes. It is rare that I ever take issue
with
> anything that Dannon says, but my own opinion is that this system doesn't
> work as well for large bowls or plates because the clay shrinks
considerably
> before you remove the canvas, and this can result in clay memory producing
> odd drying/firing warpage in your bowls or plates. However, this probably
> depends on the claybody and other variables, and it seems that Dannon has
> had good success using the canvas squares for large plates.
>
> I guess that was more than a short course after all.
> Best wishes -
> - Vince
>
> Vince Pitelka
> Appalachian Center for Craft, Tennessee Technological University
> Smithville TN 37166, 615/597-6801 x111
> vpitelka@dtccom.net, wpitelka@tntech.edu
> http://iweb.tntech.edu/wpitelka/
> http://www.tntech.edu/craftcenter/
>
>
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melpots@pclink.com.
Vince Pitelka on thu 17 jun 04
> Thanks for describing this process.. Where do you get oilcloth canvas. Is
> it the smelly stuff you used to buy at the 5 and dime for table cloths?
> Didn't think it still existed.
Jo -
If you search "canvas" on the internet, you will find suppliers that still
have oilcloth. We recently purchased a roll of regular canvas duck from
Allen Canvas, and I think they carry oilcloth.
If you use regular canvas duck, then I would use 10 ounce or 12 ounce
weight. If you use oilcloth, you should be able to get by with a lighter
weight than 10 ounce.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
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