Kim Overall on thu 12 oct 06
When throwing sections to make pots taller,
I've encountered humps I can't seem to smooth out.
If I look inside to shape, they pooch outwards.
If I look outside to shape, they pooch inside.
I've opted for the inner pooch and will trim once leatherhard.
Are there air bubbles in these joints?
Is there something I'm doing wrong here or could do better?
Kim in Houston
http://www.houstonpotters.com
Marcia Selsor on thu 12 oct 06
Hmmm, maybe you are joining the pieces a little too wet. Is your slip
lumpy?
Make sure everything is even I usually make a flat cut w/ my pin tool
and then set the pieces aside. When I come back, I score and slip
really well. The pieces are usually dry enough to pick up without
being tacky..even getting close to leather hard.
Marcia Selsor
http://marciaselsor.com
On Oct 12, 2006, at 6:06 AM, Kim Overall wrote:
> When throwing sections to make pots taller,
> I've encountered humps I can't seem to smooth out.
> If I look inside to shape, they pooch outwards.
> If I look outside to shape, they pooch inside.
> I've opted for the inner pooch and will trim once leatherhard.
>
> Are there air bubbles in these joints?
>
> Is there something I'm doing wrong here or could do better?
>
> Kim in Houston
> http://www.houstonpotters.com
Carole Fox on thu 12 oct 06
Kim-
I am assuming you are working with completed sections and then joining them.
I prefer the following method:
Throw a fat cylinder with a bottom. Keep it really thick-about an inch and
3/4 or so. Bevel the top of the cylinder down towards the inside of the
cylinder. Lightly score the beveled edge and measure the outside
circumference at the outside top edge with your calipers.
Now throw another fat cylinder with no bottom. Bevel the top of the cylinder
down to the outside this time. Make sure the circumference at the top
outside edge is the same as the measurement already taken with your
calipers. Score and slip.
Put your original cylinder back on the wheel. Turn the other open bottomed
one upside down and onto the cylinder on your wheel. Run your finger up and
down over the seam on the outside to seal. Then, run a wire between the clay
and bat of the top piece. Seal the inside seam. Throw up and down over the
seam area.
You now have a large open cylinder that you can thin and shape and it will
not look like a sectioned piece. Some clay may need a rest before attaching
the cylinders. If so, set them aside for about an hour first, My clay can
take this treatment without waiting. I have even stacked a third piece on
top with success. The sky's the limit! Or no- I guess the height of your
kiln is the limit!
Carole Fox
Silver Fox Pottery
Elkton, MD
silverfoxpottery@comcast.net
----- Original Message -----
From: "Kim Overall"
To:
Sent: Thursday, October 12, 2006 07:06 AM
Subject: sectional throwing
> When throwing sections to make pots taller,
> I've encountered humps I can't seem to smooth out.
> If I look inside to shape, they pooch outwards.
> If I look outside to shape, they pooch inside.
> I've opted for the inner pooch and will trim once leatherhard.
Richard Aerni on thu 12 oct 06
Hello Kim,
It's hard to give advice based from a distance without seeing technique, as
you could be doing something critical that you're not even aware of. You
don't say when you are joining the pieces, but for this I'm going to assume
that it's while fresh, instead of leatherhard.
Things you might wish to be aware of:
Making the thickness of the pieces to be joined equal, especially around the
joint;
Working to shape the tops of the pieces to be joined so as to facilitate the
joint...ie. Using the French technique where the upper section has a chisel
point and the lower section a "V" profile, so the pieces interlock and the
outer edges of the lower section will be pulled up and over the chisel point
of the top section when you are rethrowing the piece;
Making sure that the moisture content of both sections is as equal as you
can possibly get it...that may mean covering both areas to be joined with
plastic in order to equalize the moisture content;
Making sure that the joint area is compressed firmly after joining, so that
the joint area will closely mimic the compression given the rest of the pot
during throwing, allowing it to shrink proportionately with the rest of the
piece, and minimizing the pooching effect that you mention;
Making the joint area as close in wall thickness as possible to the areas
immediately above and below it, so that it will shrink evenly with the rest
of the pot, and eliminate as much as possible the "sucking effect" (more
shrinkage) that happens when the joint area is thicker than the rest of the
pot walls;
Working the joint more than you think necessary, especially in the
leatherhard stage, to ensure all of these things. If you feel an air bubble
(if the walls are the proper thickness, believe me, you will feel the air
bubbles), popping it, and backfilling with wet clay which you rib into the
pot. Cliff Lee told me once that to insure a good, sound joint, that he
takes each pot at the leatherhard stage and applies slip made from the clay
body to the area around each joint and ribs the pot to make sure that the
joint area is not showing;
If you are joining the pieces while still wet and throwable, these inner and
outer "pooches" that you mention are certainly able to be taken out in the
normal rethrowing that I think you would do. If you are letting the pieces
go without further shaping, and then dealing with the joints while
leatherhard, then I think the trimming and backfilling with slip would be a
good way to go.
Remember, when throwing sectionally, the old maxim of "the pot is shaped
from the inside, not the outside" is especially relevant.
Good luck with all this...I hope these tips may help you a bit, and feel
free to contact me if you are still having problems.
Richard Aerni
Rochester, NY
On Thu, 12 Oct 2006 07:06:52 -0400, Kim Overall wrote:
>When throwing sections to make pots taller,
>I've encountered humps I can't seem to smooth out.
>If I look inside to shape, they pooch outwards.
>If I look outside to shape, they pooch inside.
>I've opted for the inner pooch and will trim once leatherhard.
>
>Are there air bubbles in these joints?
>
>Is there something I'm doing wrong here or could do better?
Patrick Cross on thu 12 oct 06
I'm thinking there must be subtle differences in the diameter of the pieces
(at the joint) which you're joining....and as you work the seam the slightly
larger diameter is having to buckle to conform to the smaller. One
no-brainer way to address this is to have bats cut to the desired diameter
of the pieces you want to make...then throw all the way to the edge of the
bat. Voila' exact diameter sections.
I learned that from watching Don Reitz work (...and I think he's done enough
of that to have figured out the best way to go about it..)
Patrick Cross (cone10soda)
On 10/12/06, Kim Overall wrote:
>
> When throwing sections to make pots taller,
> I've encountered humps I can't seem to smooth out.
> If I look inside to shape, they pooch outwards.
> If I look outside to shape, they pooch inside.
> I've opted for the inner pooch and will trim once leatherhard.
>
> Are there air bubbles in these joints?
>
> Is there something I'm doing wrong here or could do better?
>
> Kim in Houston
> http://www.houstonpotters.com
>
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
Craig Clark on thu 12 oct 06
Kim, if you think there are air pockets at the seam (is this where
the pooching is occurring) then just take your pin tool and make a few
small holes where you think the air pocket is. When you make the hole(s)
have the tool angled slightly so that the direction of the hole into the
air pocket is in the direction that the wheel spins. This way, the air
is forced out of the pocket as you then throw and compress the wall
before the hole is sealed.
The problem may also be from having more clay at the seam, due to
the compressive force of joining the sections together, causing them to
swell out from the point of the union. This would be dependent upon how
soft the sections you are joining are. There are several other
possibililities for the problem. Just give me a call.
Hope this helps
Craig Dunn Clark
619 East 11 1/2 St
Houston, Texas 77008
(713)861-2083
mudman@hal-pc.org
Kim Overall wrote:
> When throwing sections to make pots taller,
> I've encountered humps I can't seem to smooth out.
> If I look inside to shape, they pooch outwards.
> If I look outside to shape, they pooch inside.
> I've opted for the inner pooch and will trim once leatherhard.
>
> Are there air bubbles in these joints?
>
> Is there something I'm doing wrong here or could do better?
>
> Kim in Houston
> http://www.houstonpotters.com
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
>
>
Kim Overall on fri 13 oct 06
Thank you so much everyone with your advice and help.
I am throwing with very little water and clay is soft.
After the first section is done, I do exactly as Carole does.
I really like Richard's "V" groove solution and will do that on the next one.
The sections are joined freshly thrown same diameters (or within 1/16"),
scored and thick slip of same clay applied to bottom piece only. After
centering and pulling height a couple times, the ribs are used in and out.
Even pressure.
Here's a link to see the inside and outside before I trimmed shaped the
inside. I also ribbed over the horizontal incised lines.
http://www.houstonpotters.com/Kim_Overall_p2.htm
Craig, I'll be over Tuesday for a lesson!
Kim in Houston
http://www.houstonpotters.com
THREE MORE WEEKS BEFORE THE TEXAS TEAPOT TOURNAMENT ENTRY MATERIALS ARE DUE!
Representational images of work are acceptable giving artists almost two
more months to finish before teapots are due (last week of December).
http://www.houstonpotters.com/TTT%202007%20online%20information%20&%20entry%20forms.pdf
Marek & Pauline Drzazga-Donaldson on sat 14 oct 06
Dear Kim,
why do you need to score when joining freshly thrown clay together, just =
slip and join. I never score when leather hard either, cuts out a =
process ( I believe it is unnecessary, even though I used it for years =
as I was tought) that is not required and does the job as well (if not =
better) as scoring.
Happy potting Marek
Hand made Architectural Ceramics from No9 Studio UK www.no9uk.com
Fully Residential Pottery Courses and more at Mole Cottage =
www.moleys.com
"Tips and Time Travel from a Vernacular Potter" reviews on =
www.keramix.com
an irreverent point of view after 35 years in the game Marek =
Drzazga-Donaldson =20
Assemble a dragon finial at www.dragonfinials.co.uk
Free Works and Mole Cottage DVD's and Video content on all the sites
Ivor and Olive Lewis on sun 15 oct 06
Dear Marek ,
Pleased to learn that you have come to trust the power of the Electron =
and the Hydrogen Bond as being the most powerful binding forces that =
operate within plastic clay.
I agree, scoring, though taught in many schools and colleges and =
supported in many books as the way to go is rarely necessary, unless =
"Keying" is required for leather hard clay.
I have found over many years that thickened deflocculated slip works =
like ant instant adhesive. It sets up so rapidly that if placement is =
not precise there is no chance to make an adjustment.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Maurice Weitman on sun 15 oct 06
At 12:29 -0400 on 10/15/06, John Britt wrote:
>He shoots =96he scores!!
Tom Coleman told me (and probably hundreds of=20
others) that he hasn't scored in years.
Who knew?
Regards,
Maurice, in chilly Fairfax, California, where our=20
street has finally been paved after three months=20
of digging, pounding, beeping, blowing clouds of=20
dirt onto our trees, plants, windows, and cars.=20
Next week we may even get hooked up to the=20
brand-new sewer line! Now if only I can get out=20
of the basement where I'm trying to finish=20
refurbing the french drains before the rains=20
start, I'll be a happy boy. Well, I'm already=20
happy. But you knew that.
Go Mets! Go Cards!! Go Tigers!!! May the best team win.
Richard Aerni on sun 15 oct 06
On Sun, 15 Oct 2006 16:34:13 +0930, Ivor and Olive Lewis
wrote:
Hello Ivor,
I'm going to speak up for scoring...
A number of years back, I thought that I'd learned enough about joining
pieces together that I could skip the scoring part. I was just slipping the
joints of pieces before putting them together. A while later I noticed I
was getting an abnormal amount of splitting at the joints after the glaze
firing, and it took me a while to put it together with my lack of scoring.
So I went back to it, and the problems disappeared.
Last year, I read with interest a comment in Ceramics Monthly by Nils Lou,
who was talking in it about the fact that scoring and slipping wasn't
necessary. He gave out a recipe for Gorilla Slip, which his students at
Linfield College were using, and which was supposed to act like a super
joiner for sectional pieces. Knowing Nils to be a man of curiosity and
thoroughness, I decided to make up a batch and use it in my work. Wow!
Talk about strange things happening! I'd unload a glaze kiln and pick up a
big piece, to have it come apart in my arms at the joints. Necks were
sliding off of the bodies of pieces that had been scored and joined with the
gorilla slip. I through that bucket out! ...and the problems stopped when
I went back to the traditional joining process.
I'm not trying to say that Nils' solution doesn't work for he and his
students, in their workspace, with their claybodies, etc. I'm not trying to
buck scientific theory about the affinity between your electrons and the
Hydrogen atom, I'm just saying that it didn't work for me. I appreciate
theory a whole bunch...I'm a kind of science oriented guy myself, but what I
appreciate most are successful results.
Just my .02...
Richard Aerni
Bloomfield, NY
>Dear Marek ,
>
>Pleased to learn that you have come to trust the power of the Electron and
the Hydrogen Bond as being the most powerful binding forces that operate
within plastic clay.
>
>I agree, scoring, though taught in many schools and colleges and supported
in many books as the way to go is rarely necessary, unless "Keying" is
required for leather hard clay.
>
>I have found over many years that thickened deflocculated slip works like
ant instant adhesive. It sets up so rapidly that if placement is not precise
there is no chance to make an adjustment.
>
>Best regards,
>
>Ivor Lewis.
>
John Britt on sun 15 oct 06
Richard,
I'm with you on the scoring. It is like in the 60=92s when a bunch of LSD
deaths occurred because the people thought that gravity was a stupid man-
made idea that did not apply to them so they tried to fly out of a 10
story window. Well, turns out that they were not so special and gravity
actually did apply. Thinking something =93profound=94 and having it actually=
work are two different things.
That article was up there with other illusions like Santa Clause, the
venturi chimney, the flat top as the best thing since sliced bread and ITC
as a cure all. Anyone with some time can search the archives for these
topics and see who and how they were pushed as brilliant ideas/solutions.
(If you search for ITC I think there are about 1300 entries.) The test of
time shows that they don=92t work any better than my mom, the regular
chimney, the arch and other refractory coatings respectively. It is not
crime believing it the first time but the trick is remembering who fed you
the line of BS and not being sucked in the next time.
Sure, slip casters use deflocculated slip for attaching small handles but
that doesn't mean that it works for teapot handles, or for 6 foot pot. No
matter how you dress it up with electron language, the "k" shell, the
indestructible forces of the universe, etc. You can even throw in the 1
law of thermodynamics, whatever; it doesn't make the handle stay on the
pot.
People can score or not as they see fit. But that will give them a chance
to learn the laws of cause and effect. Clay is very good for that. If you
don=92t wedge there is an effect, if you don=92t fire bisque slowly there is=
an effect, if you don=92t wear a dust mask there is an effect.
Unfortunately, some of the effects take years to manifest with devastating
results, others only a couple of days. Either way, brilliant or not, no
one is immune to cause and effect no matter how much they protest.
He shoots =96he scores!!
John Britt
www.johnbrittpottery.com
John Britt on mon 16 oct 06
Maurice,
Do you know if he still uses a cone six joining slip on his cone 10 work?
Thanks,
John Britt
www.johnbrittpottery.com
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