mel jacobson on sun 15 jan 12
i like to have folks think about `structure`.
if i make a tall bottles, very thin walls.....why
do they not warp?
tall thin pots do not warp, the hold their structure.
steph is a tile expert, and i do believe she
is telling us to consider `structure` of the tile.
how it is made, what clay, compression etc?
that is all structure.
when they make dry pressed tiles, they are pressed
with tons of pressure. no water, just pressure.
that is extreme `structure`. they do not warp.
i make huge platters that i fire on their sides.
they are made with fine `structure`.
they do not warp.
but, as i said the other day....how are they dried.
are they always on a flat surface?
often tiles start their warping the first day they are made.
the bigger the tile, the more they warp. are they
pressed down with weight?
if you need good advice, listen to stephanie stephenson.
she is one smart cookie, and has the right answers, or
will get them.
mel
from: minnetonka, mn
website: http://www.visi.com/~melpots/
clayart link: http://www.visi.com/~melpots/clayart.html
William & Susan Schran User on sun 15 jan 12
On 1/15/12 10:12 AM, "mel jacobson" wrote:
Mel, I'm going to agree and disagree with you on the comparisons:
> i like to have folks think about `structure`.
>
> if i make a tall bottles, very thin walls.....why
> do they not warp?
> tall thin pots do not warp, the hold their structure.
I believe tall thin walls in a pot are structurally strong because they are
in a curve, a much stronger shape than a straight, flat surface.
> steph is a tile expert, and i do believe she
> is telling us to consider `structure` of the tile.
> how it is made, what clay, compression etc?
> that is all structure.
> when they make dry pressed tiles, they are pressed
> with tons of pressure. no water, just pressure.
> that is extreme `structure`. they do not warp.
There is a small percentage of water, granted not much, but some.
They don't warp because there is not much shrinkage due to having very
little water.
> i make huge platters that i fire on their sides.
> they are made with fine `structure`.
> they do not warp.
With the platter, the clay is oriented in a curve, again a stronger form
than flat.
> but, as i said the other day....how are they dried.
> are they always on a flat surface?
> often tiles start their warping the first day they are made.
> the bigger the tile, the more they warp. are they
> pressed down with weight?
Yes, sandwich the tiles, prevent curling movement.
Why do any tiles warp - because the clay is sitting on a surface and while
drying they are shrinking. The path of least resistance is up in the air.
The edges dry first, shrink, can't go into the center because the center ha=
s
not dried, so it goes up.
So my take on drying tiles - cover the outside edges, open the center and
allow to dry. Better - cover the edges, leave center open, sandwich between
pieces of plaster drywall.
> if you need good advice, listen to stephanie stephenson.
> she is one smart cookie, and has the right answers, or
> will get them.
Yes, Stephanie is a smart and lovely cookie.
As you said before, I'm a wise ass cookie, though I think you left out the
cookie part, other times it's simply smarty pants. ;^)
All the above is IMHO and I have discovered in teaching, the absolutely bes=
t
way to learn.
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
stephani stephenson on sun 15 jan 12
I guess one easy way to observe the difference clay body can make is to=3D2=
0
to compare two very different ones.
Find the very slickest,smoothest fine particled claybody=3D20
and the coarsest claybody, (maybe a raku clay).
make similar tiles using similar methods out of both.=3D20
you can even compare pressing,rolling, cutting and extruding if you want.=
=3D
=3D20
make tiles that are 1/4 inch thick, 1/2 inch thick and 3/4 inch thick.
make tiles that are 3X3, 4X4 and 6X6. or whatever size you want.=3D20
Lay them on a board, or piece of hardibacker or drywall board
With one batch don't cover them or weight or turn them at all, just let the=
=3D
m lay=3D20
on the board and dry as fast as possible.
you'll be able to see where the EZ limits are, which clay warps at what =
=3D
size and
what thickness.
Once you understand where the EZ limits are, you can make other decisions.=
=3D
=3D20
based on what matters to you.
What mel says about structure and drying is true. What is also true is wate=
=3D
r cannot evaporate as evenly or quickly out of finegrained
clay as it can out of coarser clay, so the you'll have to help it
along more using tricks like covering the edges with thin plastic wrap to l=
=3D
et the middle dry out, or placing the=3D20
your tile boards in a damp cabinet or damp cart. if you are using a coarser=
=3D
clay, you likely wont have to do that.=3D20
there are other reasons drying on end works for me anyway. These are just =
=3D
things I have observed, I'm not laying them=3D20
out as law.
The reason I started doing it in the first place was for shelf space. large=
=3D
tiles, especially take up a lot of board and shelf space,=3D20
When I was in a very small studio, I built up horizontal drying shelves, bu=
=3D
t my shelves still got full fast, and the large
tiles just took up space for a long time. so I started pulling them off the=
=3D
boards
as soon as they stiffened , put them on their sides on a ware cart, and put=
=3D
them back to back, face to face, like slices of bread in a loaf,=3D20
and put supporting boards or bricks on each end of the loaf.
Of course you have to let the tile dry a bit before you place it on end, ju=
=3D
st enough to stiffen up enough to hold it's shape under it's own
weight .=3D20
putting them on end and especially on end in a 'loaf' or 'clamp' did 2 thi=
=3D
ngs. It naturally slowed the rate of drying , and it allowed water to evapo=
=3D
rate primarily through the end, rather than the face of the=3D20
tile. Whatever the science, once they were on the shelf I could forget them=
=3D
, though I still occasionally check them and will even turn the stack so th=
=3D
at what was the bottom edge=3D20
is now the top edge. even so, this was much less time consuming and shelf =
=3D
consuming
than the way I had worked before and i had zero problems with warping.
If you are working with smooth clay and file tile, or relief tile where th=
=3D
e relief doesn't protrude
you can let the tiles stiffen , then stack them in stacks maybe 6-12 high a=
=3D
nd weight the stacks. the tiles shouldn't be wet but they still=3D20
need to be flexible so they won't crack when the weigh is put on.=3D20
I halve a lot of half bricks around , and a 4X4 ia about the size of a hal=
=3D
f brick, so I just set a piece of cardboard or drywall board
and a halfbrick on the top of each stack. This way also works if there are
slight variations in thickness in each tile. If you are doing a 'puzzle p=
=3D
iece' mural where tiles are
odd sizes and have curves that need to line up with each other
then it is better to sandwich them laying in formation on a larger piece of=
=3D
hardibacker or drywall board.
but again, with some claybodies, you won't need to sandwich or weight the=
=3D
m.
Bisque firing them on end is no problem at all. They are very strong struct=
=3D
urally that way,as mel points out, and as they shrink, they don't have to =
=3D
drag their
=3DA0surfaces and get hung up on a shelf, which is the other reason they do=
n'=3D
t
crack so much.=3D20
I know there are aesthetic reasons for choosing clays. Some coarse clays m=
=3D
ay not give you the detail you want in carving or modelling, yet many coar=
=3D
ser bodies=3D20
will press beautifully and will, in fact give you the detail you want in pr=
=3D
essing . A lot depends on how much tile you want to make. stick with your =
=3D
own clay if it works for you, or if you are just making an=3D20
occasional tile or tile project. if you get into making a lot of tile, thes=
=3D
e issues become more important.
sorry I've gone on and on here. but if you are in a studio where you have a=
=3D
ccess to different clay bodies, from fine to coarse, including
paper clay, do a little testing to see for yourself where the=3D20
limits are for different clays.
ooof, time to get out of the chair!
Stephani Stephenson=3D20
http://www.revivaltileworks.com
Snail Scott on mon 16 jan 12
On Jan 15, 2012, at 9:57 AM, William & Susan Schran User wrote:
> I believe tall thin walls in a pot are structurally strong because they a=
re
> in a curve, a much stronger shape than a straight, flat surface...
When I teach, I cover this early in the first semester.
I call it the 'toilet paper tube theory of structural
engineering', after the prop I used to use for the demo.
I take half a manila folder and stand it on edge, showing
how it bends and curls with the least pressure. Then I
crease one and show how it stands on its own. I tape a
flat one into a tube and let it stand, then balance a brick
on it. Then I remove the brick, lay it sideways, and crush
it with my little finger.
Paper doesn't deform exactly like clay, but the lesson
really improves the way student think about the load-
bearing and deformation issues in clay. They realize
it's not just their inexperience with clay that's the
problem when their curved-under forms flatten out and
their flat walls want to fall over. It's a more fundamental
issue, and one that they can think their way through.
-Snail
John Post on mon 16 jan 12
Snail,
I do the same thing with elementary school age kids. We try to balance =3D
pencils on a sheet of paper without folds, then we count how many the =3D
kids can balance on a folded fan shape piece of paper. Instant =3D
understanding. ...and it's a contest/game.
We look at how fireman's helmets, construction worker's helmets, =3D
soldier's helmets and sports helmets incorporate bends and folds =3D
especially around rims and edges to make them stronger.
John Post
Sterling Heights, Michigan
http://www.johnpost.us
Follow me on Twitter
https://twitter.com/UCSArtTeacher =3D20
On Jan 16, 2012, at 12:43 PM, Snail Scott wrote:
>=3D20
> When I teach, I cover this early in the first semester.
> I call it the 'toilet paper tube theory of structural
> engineering', after the prop I used to use for the demo.
>=3D20
> I take half a manila folder and stand it on edge, showing
> how it bends and curls with the least pressure. Then I
> crease one and show how it stands on its own. =3D20
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