mel jacobson on fri 13 jan 12
both glazing and firing platters
can be tricky. those big spans can cover
several heat ranges.
then crack.
i have found that having a stout foot ring will
help in many ways. (i want a ring i can get my fingers around.)
firing: there is no reason you cannot use wadding on
your big platters. even if you fire electric. there are
hundreds of recipes for wood and salt firing wads. any
of them will work. i would use about eight wads on a big
platter. and, they can be small. just get the pot off the shelf.
i have seen potters fire big platters on a roll of clay..sort of
a donut. it works too. you can use white glue to stick
the wads to the bisque plate. they stay on then.
drying: when drying a big platter it is wise to get it off
a surface...like flat and stuck. in this case you can make
a big damp clay donut just the size of the inside of the ring...place
a newspaper on it...then set the pot on the donut...lifting
the piece into the air. make sure it is level. (the newspaper
keeps the piece from sticking to the donut.)
flipping: it is a good idea to flip bigger pots as they dry.
you can use a two batt system...place a batt on the rim
of the pot and flip it over. then reverse the process about
12 hours later. (this timing depends on the weather in your studio.)
you can make a rough circle with a piece of scrap plywood for
your top flipper.
flat drying: this is key. if you place any pot that is not
totally dry on a warped surface the pot will take that shape.
you may not see it, but it will warp in the kiln to the exact
shape it dried on. (the top of your electric kiln is a great
place to dry big platters for the first 24 hours.)
hole in the ring: in making all big plates i take a small drill
and put a hole in the foot ring. and then i put my signature
stamp in that spot. two reasons. 1. it lets air into the inner
ring. and it lets any gases that may come out of the pot
a place to escape during bisque firing. 2. i add a piece of pix hanging wi=
re into
the hole, secure it with a small/tiny stainless washer.
leave a long tail. the customer can then make a loop and
hang the platter like a painting. (remember, big platters do
not fit in most american cupboards...so a nail on the wall
makes a great storage place.) the hole and the sig will also
give you a reference to top/bottom for decoration purposes.
(you all know the story...that perfect poured vertical pattern
is not suppose to be horizontal, it is suppose to be vertical.
opps. but it in the wrong place.)
glazing:
when glazing, hold the pot almost vertical in your off
hand by the ring. i spin the pot as i pour glaze...flick
the fingers on the ring. of course i use a large volume
dipper made from a two cup measuring cup taped to a
stout stick. so, i hold the pot just off vertical with my
right fingers...flip the pot as i pour the glaze over the
surface, pouring with my left hand...as i am left handed.
i use wide shallow pans to hold the glaze. i get
them at fleet farm, horse/cow feeding stuff...big plastic
bushel baskets. (oil changing pans are nice too, but
not as large.) i grasp the plate with two hands on
the foot ring and plunge into the glaze. always insert
at a slight angle. (don't want that big bubble of air in
there.)
your clay: no question about it, a body with sand and
grog will always dry better and give you almost
100 percent firing success with big pots. as i have said
many times...you can compress the bottoms of big platters
until your hands bleed, but if the clay body is prone to
s cracks...it will s crack. those high talc bodies crack.
just a fact. one size does not fit all. i make a totally
different clay for platters than i do for mugs. just makes
sense. ( a pug mill is not a frivolous toy. it is the heart
of most potteries.)
there are hundreds of more tips and tricks that potters
use for big stuff. it does make for creative thinking when
your scale increases.
mel
from: minnetonka, mn
website: http://www.visi.com/~melpots/
clayart link: http://www.visi.com/~melpots/clayart.html
Soj on sat 14 jan 12
On Fri, 13 Jan 2012 07:56:13 -0600, mel jacobson wrot=
=3D
e:
> both glazing and firing platters
>can be tricky. those big spans can cover
>several heat ranges.
>
>then crack.
>
>i have found that having a stout foot ring will
>help in many ways. (i want a ring i can get my fingers around.)
I've been working on a large platter, textured inside, which I would like=
=3D
to
be able to repeat and stack. I've been told that one cannot put a foot o=
=3D
n
such a platter. I've been wracking my brains trying to come up with a
method to get a foot (or feet) on this thing and thus far I find myself
stymied at every turn. I would also like the curve of the platter to be
repeatable/consistent between platters so as to make stacking (for storag=
=3D
e)
easier. So far I'm on iteration 3 of my first attempt. I typically do
wheel work and not slab building so there are a lot of firsts in this
project for me.
I'd like to use a hump mold to get the curve consistency but because of t=
=3D
he
interior texture I've been told this isn't feasible. I thought of making=
=3D
a
version of the platter with the interior texturing exaggerated, bisqueing=
=3D
that, then pressing a slab into the bisqued "mold" with a roller, bisquei=
=3D
ng
THAT and then using that as a textured hump mold (using a roller to press=
=3D
the slab over the mold should hopefully transfer a fair copy of the inter=
=3D
ior
texture, I hope).
If I can get that to work, then I could still apply a foot ring or feet, =
=3D
I
could reliably repeat the curvature between platters, and I wouldn't have=
=3D
to
add the texture to each and every platter by hand (think veining on a lea=
=3D
f).
Does that sound like something that could work? The problem I can forese=
=3D
e
with this is getting the interior texture to transfer reliably (veins in =
=3D
a
leaf, can't be too coarse and can't be too deeply incised or it'll look w=
=3D
rong).
The studio director hasn't been very encouraging - the idea of making mor=
=3D
e
than one of a piece seems to bother her. However this is a large plate
intended for meal time use and even if I never made it for anyone else, I=
=3D
'd
like to have at least 4 for myself. I don't WANT them all to be differen=
=3D
t,
I could never store them! I tried a sling mold, the platter dried crooke=
=3D
d -
apparently I didn't get it quite centered in the sling. This doesn't bod=
=3D
e
well for repeatability (and that was the end of iteration 2).
The other alternative I could think of is to get a large piece of dense
foam, cut an outline of the platter into it with sloped sides (it's rough=
=3D
ly
ovoid in shape) and use that as a slump mold. If that makes sense. I wo=
=3D
uld
still have to do the texturing by hand before moving the slab to the slum=
=3D
p
mold, but at least I'd end up with a common curvature and (hopefully)
stackable platters. The thing I'm not sure about is that there is a desi=
=3D
gn
cut into the edges of the platters which I would have to do after placing=
=3D
the slab in the hump mold, which could cut the mold up if I do it IN the
mold. The only other way to get this done that I can think of would be t=
=3D
o
do the texturing, cut the rim design, flip the entire slab so it's upside=
=3D
down, then flip it BACK onto a piece of Tevlek, then manipulate the TEVLE=
=3D
K
(like sort of a hammock) to get the whole thing into the slump mold and l=
=3D
et
it dry that way. This would be the cloth kind of Tevlek like they make
kites out of and not the paper kind of Tevlek like they make envelopes an=
=3D
d
house wrap out of. But the problem with a slump mold is - no foot ring o=
=3D
r feet!
I'm concerned about the raw, unglazed bottom scratching up the surface of=
=3D
a
dining table if there are no feet or a foot ring - again, I'm being told
there is no way to make sure you have a smooth surface on that bottom tha=
=3D
t
won't mar a table surface. The only idea she had for this was to coat th=
=3D
e
bottom with terra sig after it's dried enough to flip the platter. The
first time I tried this my platter cracked at the edges where there is a
design cut into the edges. That was the end of iteration 1, LOL!=3D20=3D20
Any ideas about how to overcome some of these problems would be most
appreciated. I'm using an earthenware clay body with a small amount of
grog. I'm painting the top surface with a thin yellow mason stain slip,
then will overglaze with a semi-transparent green after bisqueing. A tes=
=3D
t
tile shows this combination to be a semi-natural looking green leaf color=
=3D
.
I'd really like to work this out some way.
Vince Pitelka on sun 15 jan 12
Soj wrote:
"I'd like to use a hump mold to get the curve consistency but because of th=
e
interior texture I've been told this isn't feasible. I thought of making a
version of the platter with the interior texturing exaggerated, bisqueing
that, then pressing a slab into the bisqued "mold" with a roller, bisqueing
THAT and then using that as a textured hump mold (using a roller to press
the slab over the mold should hopefully transfer a fair copy of the interio=
r
texture, I hope).
Hi Soj -
I am not sure who told you that it was not feasible to slump a textured
platter face-down over a slump mold, but that's an odd generalized
statement. I suppose it depends on the type of texture. If the texture
involves a lot of high points scattered over a recessed background, then
certainly the texture would be damaged. On the other hand, if most of the
texture or pattern is impressed and there is still a reasonable amount of
the original surface, then it can be slumped face-down with no damage to th=
e
pattern. I teach a slab-built tableware workshop where we often texture th=
e
slabs with bisque-stamps and rollers and then slump them face-down on molds
to make bowls, plates, and platters. The texture is not damaged at all as
long as you do not press down too hard against the slab while slumping it,
and there is no reason to press down much at all.
I always add foot-rings to my slumped bowls, plates, and platters, and in
fact this is one of the primary advantages of slumping such forms face-down
rather than slumping the into a mold face-up. When slumping face-down you
can add the foot ring immediately, when it has the greatest chances of
survival without any warping or cracking problems. You can make the foot
ring from a rolled coil, or from a strip cut off the long edge of a slab,
thoroughly scoring and applying slurry to attach it, and then dressing it
down with fingers and sponge to form its final shape. In grad school I mad=
e
a lot of 22"-diameter slumped-slab platters with intricate inlaid colored
clay imagery (you can see some of them at
http://iweb.tntech.edu/wpitelka/gallery/early%20work/early_work.htm) and
slumped them face-down on large domed plaster bats. I immediately put the
bat on a potter's wheel, scored and slurried two concentric rings on the
back-side of the platter, added thick coils of clay, worked them into the
surface, and then threw them to form the foot rings. As long as I did this
right away to the freshly-slumped platter, I did not have problems with the
foot ring cracking or separating.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net
http://iweb.tntech.edu/wpitelka/
Eleanora Eden on sun 15 jan 12
Hi Soj,
While your platter, whatever its size or shape, is upside-down over a
slump mold, a foot can be thrown onto it, using the same clay body.
I've used this strategy extensively over the years and it works fine.
You can throw the ring in advance and apply it, wet, with spooze or
whatever you use. Using your chamois you can smooth the foot
surface by forcing down the stuff in the clay that makes a rough surface.
Then enclose the whole thing in plastic and let the moisture in the two
get balanced, like applying a handle etc.
Perhaps to try this you would center the slump mold on the wheel in
advance and do the whole process on the wheel.
Just my 2c. Hope this helps.
Eleanora
>
>
>I've been working on a large platter, textured inside, which I would like =
to
>be able to repeat and stack. I've been told that one cannot put a foot on
>such a platter. I've been wracking my brains trying to come up with a
>method to get a foot (or feet) on this thing and thus far I find myself
>stymied at every turn. I would also like the curve of the platter to be
>repeatable/consistent between platters so as to make stacking (for storage=
)
>easier. So far I'm on iteration 3 of my first attempt. I typically do
>wheel work and not slab building so there are a lot of firsts in this
>project for me.
>
>I'd like to use a hump mold to get the curve consistency but because of th=
e
>interior texture I've been told this isn't feasible. I thought of making =
a
>version of the platter with the interior texturing exaggerated, bisqueing
>that, then pressing a slab into the bisqued "mold" with a roller, bisquein=
g
>THAT and then using that as a textured hump mold (using a roller to press
>the slab over the mold should hopefully transfer a fair copy of the interi=
or
>texture, I hope).
>
>If I can get that to work, then I could still apply a foot ring or feet, I
>could reliably repeat the curvature between platters, and I wouldn't have =
to
>add the texture to each and every platter by hand (think veining on a leaf=
).
>
>Does that sound like something that could work? The problem I can foresee
>with this is getting the interior texture to transfer reliably (veins in a
>leaf, can't be too coarse and can't be too deeply incised or it'll look wr=
ong).
>
>The studio director hasn't been very encouraging - the idea of making more
>than one of a piece seems to bother her. However this is a large plate
>intended for meal time use and even if I never made it for anyone else, I'=
d
>like to have at least 4 for myself. I don't WANT them all to be different=
,
>I could never store them! I tried a sling mold, the platter dried crooked=
-
>apparently I didn't get it quite centered in the sling. This doesn't bode
>well for repeatability (and that was the end of iteration 2).
>
>The other alternative I could think of is to get a large piece of dense
>foam, cut an outline of the platter into it with sloped sides (it's roughl=
y
>ovoid in shape) and use that as a slump mold. If that makes sense. I wou=
ld
>still have to do the texturing by hand before moving the slab to the slump
>mold, but at least I'd end up with a common curvature and (hopefully)
>stackable platters. The thing I'm not sure about is that there is a desig=
n
>cut into the edges of the platters which I would have to do after placing
>the slab in the hump mold, which could cut the mold up if I do it IN the
>mold. The only other way to get this done that I can think of would be to
>do the texturing, cut the rim design, flip the entire slab so it's upside
>down, then flip it BACK onto a piece of Tevlek, then manipulate the TEVLEK
>(like sort of a hammock) to get the whole thing into the slump mold and le=
t
>it dry that way. This would be the cloth kind of Tevlek like they make
>kites out of and not the paper kind of Tevlek like they make envelopes and
>house wrap out of. But the problem with a slump mold is - no foot ring or=
feet!
>
>I'm concerned about the raw, unglazed bottom scratching up the surface of =
a
>dining table if there are no feet or a foot ring - again, I'm being told
>there is no way to make sure you have a smooth surface on that bottom that
>won't mar a table surface. The only idea she had for this was to coat the
>bottom with terra sig after it's dried enough to flip the platter. The
>first time I tried this my platter cracked at the edges where there is a
>design cut into the edges. That was the end of iteration 1, LOL!
>
>Any ideas about how to overcome some of these problems would be most
>appreciated. I'm using an earthenware clay body with a small amount of
>grog. I'm painting the top surface with a thin yellow mason stain slip,
>then will overglaze with a semi-transparent green after bisqueing. A test
>tile shows this combination to be a semi-natural looking green leaf color.
>
>I'd really like to work this out some way.
--
Bellows Falls Vermont
www.eleanoraeden.com
Ellen and Tom on sun 15 jan 12
Dear Soj,
I agree with Vince. I work with textured slabs all
the time and the patterns stay just fine whether I
put them face down onto a form or face up. I use
fairly stiff clay (we make our own) with 10 percent
fine grog for slab work. It is stiff enough that when
you pick up the slab it doesn't stretch out at the
corners, but soft enough to lightly press down into or
onto the form with a dry yellow sponge. After the
initial pressing into the form I usually place a very
thin piece of plastic over the form and press more
firmly, again with a yellow sponge in my fingers.
Try it. You will be surprised that you do not
disturb the pattern doing this, as long as you do not
press too hard in one place.
I'm 79 and have changed from throwing everything to
making about 60 percent of my work with slabs.
It helps to use different parts of your body rather than
working all the time at the wheel, and I found that
slab work greatly increased the variety of forms I can
offer my customers.
For forms I have collected a great number of thrift
store trays, bowls etc. Wood, glass, metal, plastic.
They are much lighter than plaster forms and take a
lot less time than making them of wood or foam board.
If I wanted to make stackable, same size plates with
a texture. I would choose the appropriate form, brush on
a very fine coat of WD-40 (works best, but you can use
Pam if you are afraid of WD-40), roll out the appropriate
sized slab, texture it, lay it onto or into the form, and
lightly press with a sponge, and then with a sponge on
top of plastic. If you have the texture face down, you
can also use a wet yellow sponge to lightly sponge all
over the back for a very smooth surface, and you can
put your piece onto the wheel and throw a foot ring on it.
Right away if you wish, but I often wait until the next
day when the clay is a bit firmer but still damp enough
to attach a foot ring. (You will need to do a bit of clean-up
on the rim at some point. I like to do it before I put
on the foot ring.) I try to do these in series so that
I do a number of foot rings at the same time. I throw
a cylinder on one wheel, cut off rings of about the
right size as I need them for each foot ring, score and
attach, and then (with the pot centered on my second
wheel) throw the foot ring to the appropriate
size. I sometimes support the form with layers of
firm foam, but I've learned to use a pretty light hand
in throwing the footring.
I usually dry these under plastic for a day or so, and then
put them into a damp closet until the surface has turned
color. Then onto shelves lined with sheetrock. Some
forms do best dried on their rims, and some do not. You
have to figure that out for your own clay. And if you use
found forms you will need to learn which work best.
If your pattern extends to the edge of the piece you have to
be a bit more careful when you clean up that edge. I mostly
leave a untextured border on plates and shallow trays, making
it easier to have a nice smooth edge.
Ellen Currans
First snow of the winter here in Oregon this morning.
Probably won't last long.
-----Original Message-----
From: Soj
To: Clayart
Sent: Sat, Jan 14, 2012 11:59 pm
Subject: Re: platters/ the story
On Fri, 13 Jan 2012 07:56:13 -0600, mel jacobson =3D20
wrote:> both glazing and firing platters>can be tricky. those=3D20
big spans can cover>several heat ranges.>>then crack.>>i have found=3D20
that having a stout foot ring will>help in many ways. (i want a ring i=3D2=
0
can get my fingers around.)I've been working on a large platter,=3D20
textured inside, which I would like tobe able to repeat and stack. =3D20
I've been told that one cannot put a foot onsuch a platter. I've been=3D20
wracking my brains trying to come up with amethod to get a foot (or=3D20
feet) on this thing and thus far I find myselfstymied at every turn. =3D20
I would also like the curve of the platter to berepeatable/consistent=3D20
between platters so as to make stacking (for storage)easier. So far=3D20
I'm on iteration 3 of my first attempt. I typically dowheel work and=3D20
not slab building so there are a lot of firsts in thisproject for=3D20
me.I'd like to use a hump mold to get the curve consistency but because=3D2=
0
of theinterior texture I've been told this isn't feasible. I thought=3D20
of making aversion of the platter with the interior texturing=3D20
exaggerated, bisqueingthat, then pressing a slab into the bisqued=3D20
"mold" with a roller, bisqueingTHAT and then using that as a textured=3D20
hump mold (using a roller to pressthe slab over the mold should=3D20
hopefully transfer a fair copy of the interiortexture, I hope).If I can=3D2=
0
get that to work, then I could still apply a foot ring or feet, Icould=3D20
reliably repeat the curvature between platters, and I wouldn't have=3D20
toadd the texture to each and every platter by hand (think veining on a=3D2=
0
leaf).Does that sound like something that could work? The problem I=3D20
can foreseewith this is getting the interior texture to transfer=3D20
reliably (veins in aleaf, can't be too coarse and can't be too deeply=3D20
incised or it'll look wrong).The studio director hasn't been very=3D20
encouraging - the idea of making morethan one of a piece seems to=3D20
bother her. However this is a large plateintended for meal time use=3D20
and even if I never made it for anyone else, I'dlike to have at least 4=3D2=
0
for myself. I don't WANT them all to be different,I could never store=3D20
them! I tried a sling mold, the platter dried crooked -apparently I=3D20
didn't get it quite centered in the sling. This doesn't bodewell for=3D20
repeatability (and that was the end of iteration 2).The other=3D20
alternative I could think of is to get a large piece of densefoam, cut=3D20
an outline of the platter into it with sloped sides (it's roughlyovoid=3D20
in shape) and use that as a slump mold. If that makes sense. I=3D20
wouldstill have to do the texturing by hand before moving the slab to=3D20
the slumpmold, but at least I'd end up with a common curvature and=3D20
(hopefully)stackable platters. The thing I'm not sure about is that=3D20
there is a designcut into the edges of the platters which I would have=3D20
to do after placingthe slab in the hump mold, which could cut the mold=3D20
up if I do it IN themold. The only other way to get this done that I=3D20
can think of would be todo the texturing, cut the rim design, flip the=3D20
entire slab so it's upsidedown, then flip it BACK onto a piece of=3D20
Tevlek, then manipulate the TEVLEK(like sort of a hammock) to get the=3D20
whole thing into the slump mold and letit dry that way. This would be=3D20
the cloth kind of Tevlek like they makekites out of and not the paper=3D20
kind of Tevlek like they make envelopes andhouse wrap out of. But the=3D20
problem with a slump mold is - no foot ring or feet!I'm concerned about=3D2=
0
the raw, unglazed bottom scratching up the surface of adining table if=3D20
there are no feet or a foot ring - again, I'm being toldthere is no way=3D2=
0
to make sure you have a smooth surface on that bottom thatwon't mar a=3D20
table surface. The only idea she had for this was to coat thebottom=3D20
with terra sig after it's dried enough to flip the platter. Thefirst=3D20
time I tried this my platter cracked at the edges where there is=3D20
adesign cut into the edges. That was the end of iteration 1, LOL! Any=3D2=
0
ideas about how to overcome some of these problems would be=3D20
mostappreciated. I'm using an earthenware clay body with a small=3D20
amount ofgrog. I'm painting the top surface with a thin yellow mason=3D20
stain slip,then will overglaze with a semi-transparent green after=3D20
bisqueing. A testtile shows this combination to be a semi-natural=3D20
looking green leaf color.I'd really like to work this out some way.
=3D20
stephani stephenson on sun 15 jan 12
Soj,=3D20
I know some folks who make dinnerware and banquetware, including various st=
=3D
yle large platters and=3DA0 what i would call large platter/bowls , for res=
ta=3D
urants. Some of the serving platters and bowls have no footrings, but a cou=
=3D
ple of=3DA0 styles do.
Platters are formed=3DA0 by slumping slabs in slump molds.Footrings=3DA0 ar=
e ma=3D
de separately. I can't remember if they throw the footrings , but possibly =
=3D
they do. The foot rings are pretty high, as the idea is to elevate the plat=
=3D
ter/bowl above the table.=3DA0 They have=3DA0 figured out just the right si=
ze a=3D
nd angle for the footring ,and they are made=3DA0 to fit well.=3D20
Platter/bowls=3DA0 and=3DA0 foot rings=3DA0 are stacked=3DA0 separately in =
the bisq=3D
ue firing. The nice thing is, just about any footring will fit with any pla=
=3D
tter/bowl. After bisque, they=3DA0 might dry fit each platter to each foot=
ri=3D
ng first, to make sure the two individual pieces fit well, I'm not sure.=3D=
20
The entire platter/bowl=3DA0 is glazed top and bottom, inside and out,=3DA0=
and=3D
set=3DA0 atop the foot ring on the kiln shelf in preparation for glaze fir=
in=3D
g. They use a car kiln so it is easy to=3DA0 eyeball if it is set=3DA0 on s=
trai=3D
ght. Maybe they have a way of keying it on straight, or maybe they are just=
=3D
good at it. I can't remember if they=3DA0 glaze the foot ring. The melted =
gl=3D
aze is=3DA0 what holds the two together . They come out in one piece from t=
he=3D
glaze fire. every once and awhile one would have been set on a little croo=
=3D
ked and fired that way, but it was pretty rare.
personally ,I was skeptical about how good of a bond this would make. I had=
=3D
tried this=3DA0 on a few things, of my own , but=3DA0 I was never sure I c=
ould=3D
trust the glaze bond. Yet=3DA0 they have=3DA0 it figured it out for their =
shap=3D
es and glazes. They=3DA0 make it work consistently and=3DA0 they make a lot=
of =3D
these. These platters are given a workout in the restaurant and banquet wor=
=3D
ld, so they must be good enough to take the abuse without falling apart. th=
=3D
ey are fired to cone 6.
just another approach.
Stephani Stephenson
Lee on sun 15 jan 12
A problem with grog is that it weakens the fired body.
I was always amazed at my teacher's studio. After the large platters
were trimmed, they were dried sitting on the newly trimmed feet.
They never cracked.
It may be the reason natural clays are stronger in the drying
compared to commercially formulated clays from industrial materials,
is the mixed particle size. Traditional clays are not screened to
200 mesh etc. like industrial clays are. Mixed particle size
provides a similar drying strength as grog does, without weaking the
fired body.
--
=3DA0Lee Love in Minneapolis
http://mingeisota.blogspot.com/
=3DA0"Ta tIr na n-=3DF3g ar chul an tI=3D97tIr dlainn trina ch=3DE9ile"=3D9=
7that is, =3D
"The
land of eternal youth is behind the house, a beautiful land fluent
within itself." -- John O'Donohue
Vince Pitelka on sun 15 jan 12
Lee Love wrote:
"It may be the reason natural clays are stronger in the drying compared to
commercially formulated clays from industrial materials, is the mixed
particle size. Traditional clays are not screened to 200 mesh etc. like
industrial clays are. Mixed particle size provides a similar drying
strength as grog does, without weakening the fired body.
Lee -
I am not picking on you, but I'd be curious to hear your justification for
the above. Grog does not weaken the fired claybody if it is not used in
excessive amounts. The mixed particle size is the whole point, and can be
easily orchestrated in claybody formulation. Dry strength has to do with
reducing the amount of porosity and increasing the number of contact points
between particles, and that depends on green-packing density, as Dave
Finkelnburg has explained. Designing a claybody for maximum green-packing
density results in greater plasticity and standing structure, lower drying
shrinkage, greater dry and bisque strength, and lower firing shrinkage. It
is win-win in every sense. Except for some rare natural blends, pure
natural clays rarely match the dry strength of well-formulated claybodies.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net
http://iweb.tntech.edu/wpitelka/
Alice DeLisle on mon 16 jan 12
"I'd like to use a hump mold to get the curve consistency but because of =
=3D
the
interior texture I've been told this isn't feasible."
You can stretch quilt batting over the mold and it will help protect the =
=3D
texture. It is like a very thin layer of foam. You can usually apply =3D
quite a bit of pressure to the clay after putting it on the mold with =3D
batting without too much damage to the texture.
Alice DeLisle
wanderland@att.net
http://www.etsy.com/shop/IslandTextures
http://www.flickr.com/photos/alice_delisle/
Lis Allison on mon 16 jan 12
On January 15, 2012, stephani stephenson wrote:
>
> Platter/bowls and foot rings are stacked separately in the bisque
> firing.
Hmmm. I dunno about that. Maybe this works in industrial applications, but
for a studio potter it is pretty hard to do. I've tried it a number of
times and the foot ring never properly fits after the glaze firing. I
think the angle between the foot and the main piece has to be totally
matched, and they can't be displaced even a tiny bit in the glaze firing
because if they are they will move relative to each other.
After a dozen or so attempts, none of which had the foot totally attached
to the top, I gave up and now throw the foot ring on to the top like other
people have suggested. This works fine. I found it helped to extrude a
coil for the foot ring, but if you do, make sure you work the clay well
before pulling up the foot ring to eliminate the corkscrew stresses in the
coil.
Lis
--
Elisabeth Allison
Pine Ridge Studio
website: www.pine-ridge.ca
Pottery blog: www.studio-on-the-ridge.blogspot.com
Garden blog: www.garden-on-the-ridge.blogspot.com
Lis Allison on mon 16 jan 12
On January 16, 2012, Alice DeLisle wrote:
> "I'd like to use a hump mold to get the curve consistency but because
> of the interior texture I've been told this isn't feasible."
>
> You can stretch quilt batting over the mold and it will help protect
> the texture. It is like a very thin layer of foam. You can usually
> apply quite a bit of pressure to the clay after putting it on the mold
> with batting without too much damage to the texture.
Good point. Old nylons - ie pantyhose - work well too.
Lis
--
Elisabeth Allison
Pine Ridge Studio
website: www.pine-ridge.ca
Pottery blog: www.studio-on-the-ridge.blogspot.com
Garden blog: www.garden-on-the-ridge.blogspot.com
Soj on fri 20 jan 12
First I want to thank everyone for their responses. I'm slow, but I do g=
=3D
et
around to things eventually!
The encouragement and the ideas have been most welcome. Especially, gett=
=3D
ing
confirmation that I should indeed be able to do this on a hump mold and g=
=3D
et
a foot ring on there without squishing the interior texture into oblivion=
=3D
!=3D20
Here's my latest scheme:
My preference would be to make a plaster mold but for several reasons tha=
=3D
t's
not the most feasible idea at the moment (mostly having to do with
transportation and storage issues)
What I think could work instead is to throw a large ring. Let that set u=
=3D
p a
bit so it can be removed but is still malleable enough to deform into an
oval. Well, ovoid, as the platter is narrower at the top than the bottom=
=3D
.=3D20
Anyway. Once I've got it cut 'n pasted into the correct shape, bisque fi=
=3D
re
that. If I wanted just the slump mold I could quit here.
Now take that and use it to make a hump mold from a slab, no decorations
just a slab of clay cut into the proper shape. Taller than the ultimate
platter will be deep so there's room for it to fit without dragging at th=
=3D
e
edges. Bisque THAT. Now I have my hump mold in bisque.
Now I can texture and cut my platter, then flip it onto a piece of
Kite-Tyvek, as a sling. Lifting the tyvek-sling I can move the platter (=
=3D
now
face down) to the bisqued hump mold and get it centered on there without
stretching the platter or messing up the texture should I have to reposit=
=3D
ion
it on the hump mold a little.
Am I getting it?
I really appreciate the help I've gotten from you folks. It's like havin=
=3D
g
50 mentors, LOL!
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