Them wobbles - wheel throwing

Yeah - here I am again! Nag nag nag! LOL!

So - I have been doing some pretty good work on the wheel lately. When I
finally realized that I was using too firm clay, the centering go a lot
easier!

But - even if I have wedged the clay thoroughly just before slapping it on
the wheel, I sometimes get this wobble in the middle. I feel it as I am
opening out, that the middle just does not want to be the middle, if you get
what I mean. I am thinking (gee! WOW!) that I might not have coned the clay
up well enough in the beginning? Or are some bits of clay just not willing
to conform? I have seen a lot of potters throwing pretty uncentered pieces,
but I wonder if the middle is uncentered or just the outside?

Once again, thanks to you guys for being around. You have the experience
that I can't find from anyone else around these parts!

Marianne

PS - asked my dealer about cones, and he doesn't carry them and doesn't find
them useful at all. Will try to remember to talk with my teacher about it on
Friday.

"Bubbles_"

I have seen a lot of potters throwing pretty uncentered pieces,
but I wonder if the middle is uncentered or just the outside?

Remember that the clay on the spinning wheel will want to travel outward, so
you need to keep squeezing inward as you raise the walls. Wobbles can
be worked around, but it's always better to spend some additional time to
minimize them -- they're becomes especially painful when you're trimming :-)

PS - asked my dealer about cones, and he doesn't carry them and doesn't
find
them useful at all. Will try to remember to talk with my teacher about it on
Friday.

I don't like being blunt but your dealer's an idiot. There's no way to
measure
heat-work except through the use of cones. I use a pyrometer and cones, but
the pyrometer's just to give me an estimate of heat, it cannot tell me the
amount
of heat-work being done on the clay -- that's what cones are for. They're
invaluable in repeating firings, especially when the kiln load is
significantly
different between firings; the cones will allow you to consistently repeat
your
firings (plus alot of other things). I can easily fire wihout the
pyrometer, but
certainly not without cones.

Best -
Peter
NM

"Peter" wrote in message
. ..

"Bubbles_"

I have seen a lot of potters throwing pretty uncentered pieces,
but I wonder if the middle is uncentered or just the outside?

Remember that the clay on the spinning wheel will want to travel outward,
so
you need to keep squeezing inward as you raise the walls. Wobbles can
be worked around, but it's always better to spend some additional time to
minimize them -- they're becomes especially painful when you're trimming
:-)

PS - asked my dealer about cones, and he doesn't carry them and doesn't
find
them useful at all. Will try to remember to talk with my teacher about it
on
Friday.

I don't like being blunt but your dealer's an idiot. There's no way to
measure
heat-work except through the use of cones. I use a pyrometer and cones,
but
the pyrometer's just to give me an estimate of heat, it cannot tell me the
amount
of heat-work being done on the clay -- that's what cones are for. They're
invaluable in repeating firings, especially when the kiln load is
significantly
different between firings; the cones will allow you to consistently repeat
your
firings (plus alot of other things). I can easily fire wihout the
pyrometer, but
certainly not without cones.

Best -
Peter
NM


I agree with Peter 100% on this. Sure you can fire without cones but it is
not wise. For example you stated that you soaked for 40 minutes. There is
no way you can know what the heat work was that you reached without cones.
As I said, I dropped my temperture by 10 degrees F to get the heat work I
needed with a 30 minute soak. You said that you suspected that you were
firing 20 degrees C less than what your kiln said it was doing. That is a
huge amount. This is something you should know and cones will tell you.

About centering - I can't imagine someone throwing an acceptable pot if it
is not centered. First off, take as much work out of the process as you can
by patting to center.

I love this UTube - his clay before he even begins throwing is a work of
art.

http://www.youtube.com/watch?v=PxyZ6... 684E1&index=1

Always remember to remove your hands slowly from the clay when you have it
centered or else you risk knocking if off center as you move away.

When you think that the piece is centered check it with a needling tool -
both sides and top. If it is centered, do your initial opening. Now check
to see if the opening is centered with your needling tool (you are using
your needling tool the same way you do when you are checking if your are
centered for trimming. If both the outer an inner walls are centered and
you are getting wobbles you have two things left. When you opened up the
floor you did not maintain the level of your fingers as you pulled out and
you opened slowly enough that your floor is not level (really hard to do but
possible). The other is that you have air bubbles in the clay. Large
enough ones will make your walls uneven.

http://www.youtube.com/results?searc...centering+clay

But what it all comes down to is doing it over and over and over. 5000
hours you will be a professional (that is the time estimate from
Psychologist Don Norman)!

P.S. a vent is a good thing to have on your kiln - firing it with the peep
holes open is not.

"DKat" wrote in message
...
P.S. a vent is a good thing to have on your kiln - firing it with the
peep holes open is not.


I have three venting holes - one high, one low, and one in the middle of the
lid. Not good to use for peeping.

:-)

Marianne

Does you kiln instructions call these venting holes? Usually venting is
done with really small holes in the bottom of the kiln with a fan pulling
the air out. You typically get more than enough air for this venting from
the crack opening in the lid. You don't need air for firing since you are
not using a flame, you just need to get rid of the nasty chemicals that
pottery puts off. The venting pulls out these chemicals and circulates the
heat so you get more even heating. Leaving peep holes open is going to give
you cold spots where are bad and could be giving you your blisters. The 3
holes in the side of the kiln are typically called peep holes (you should
use glasses to look in them) and this is where you check your cones to make
sure you haven't over or under fired. I kiln should ALWAYS be monitored in
some fashion especially at critical temperatures (like when you expect it to
stop heating).

Just something you might want to examine a little closer.

Donna

"Bubbles_" wrote in message
...

"DKat" wrote in message
...
P.S. a vent is a good thing to have on your kiln - firing it with the
peep holes open is not.


I have three venting holes - one high, one low, and one in the middle of
the lid. Not good to use for peeping.

:-)

Marianne

"DKat" wrote in message
news
I agree with Peter 100% on this. Sure you can fire without cones but it
is not wise. For example you stated that you soaked for 40 minutes.
There is no way you can know what the heat work was that you reached
without cones. As I said, I dropped my temperture by 10 degrees F to get
the heat work I needed with a 30 minute soak. You said that you suspected
that you were firing 20 degrees C less than what your kiln said it was
doing. That is a huge amount. This is something you should know and
cones will tell you.

I think Europeans use more advanced thermal computers than Americans do. The
next one I get will also let me control the cooling process.

I have seen so many lovely pieces made without using cones in firing, that I
can't quite agree with you guys. Also when it comes to reproducing a firing
to bring about the same colors/effects with the glaze.

About centering - I can't imagine someone throwing an acceptable pot if it
is not centered. First off, take as much work out of the process as you
can by patting to center.

I love this UTube - his clay before he even begins throwing is a work of
art.

http://www.youtube.com/watch?v=PxyZ6... 684E1&index=1

Like wow - this guy has done this a couple of times before! Thanks for
sharing.

_snip great advice_

Okay - I'm about 400 hours in now, maybe! Only 4600 more to go! LOL!

Have a great day.

Marianne

----- Original Message -----
From: "Bubbles_"
I think Europeans use more advanced thermal computers than Americans do.
The next one I get will also let me control the cooling process.


No Europeans do not have more advanced thermal computers than Americans do.
Again you are talking Temperature vs Heat work. They are critically
different. I don't know how else to say it other than they are correlated
but not the same.
http://www.hotkilns.com/What%20Cone%...ers%20Mean.pdf
I have seen so many lovely pieces made without using cones in firing, that
I can't quite agree with you guys. Also when it comes to reproducing a
firing to bring about the same colors/effects with the glaze.


And yes I believe Europeans can do beautiful work without the aid of cones -
I have fired simply based on the color of the kiln with a gas or raku kiln.
But we are not talking about people who are not having problems and trying
to solve what is wrong with their firing. If they are getting perfectly
beautiful pots then they are not having issues. What we are talking about
here is a kiln where you don't know what the temperature is let alone the
heat work AND you are having problems with your glazes. To me it seems
critical that the first thing you find out is what heat work you are getting
at various places in your kiln. JMO of course but it is difficult to give
advice without the proper information.



About centering - I can't imagine someone throwing an acceptable pot if
it is not centered. First off, take as much work out of the process as
you can by patting to center.

I love this UTube - his clay before he even begins throwing is a work of
art.

http://www.youtube.com/watch?v=PxyZ6... 684E1&index=1

Like wow - this guy has done this a couple of times before! Thanks for
sharing.

_snip great advice_

Okay - I'm about 400 hours in now, maybe! Only 4600 more to go! LOL!

Have a great day.

Marianne


Are we having fun yet? Hope you get a good firing soon. We need the
variable reinforcement to keep us addicted...

Donna

I do know about what temperature I am firing at. It is NOT out by 20
degrees, that has been established.

I have done only 40 firings (including bisque) with this kiln, so it still
is taking some getting used to.

Even in that last kiln, I had a couple of pieces turn out really great. The
clue is to figure out where I can fire so ALL (or almost all) the pieces
turn out lovely. I don't use just one glaze, so my milage varies
accordingly. The piece that bubbled the most was a combination I was trying
for the first time.

I'm sorry, Donna, but the people I know here who have electric kilns of
varying sizes never use cones and they produce beautiful sculptures and
crockery and you name it. If they can manage without cones, I am not going
to stand on my head and run around Europe to try to find some - I will try
their suggestions about temperature increases first. Even if my thermostat
is slightly off, it will always be off by the same amount or percent, so
that I will refire at 5 degrees more, then 10 degrees more.

Keep smiling.

Marianne

In article , DKat
says...

Again you are talking Temperature vs Heat work. They are critically
different. I don't know how else to say it other than they are correlated
but not the same.

In simple terms: imagine a plot of temperature against time for the
firing cycle. Now draw a line across at the minimum temperature that
the glaze will flow. The relevant heat work is the /area/ under the
curve but above that line, and is dependent on both temperature and
time.
Cones reflect this because they sag faster at higher temperatures, and
sag more with time at any particular temperature above their
characteristic minimum temperature.