Cant Pull Beyond 12 Inches

[preeta]

i am totally flummoxed!!!

 

I cant pull a cylinder beyond 12 inches. 

 

meaning i try to pull up but everything happens except gain height. instead i get groove lines, wonky uncentered cylinder - anything but height. i tried using a sponge but the clay wont move. i tried standing and using a rib. 

 

what am i doing wrong? does this happen? is this normal?

 

HELP?!

[Mark C.]

Use more clay or better clay with legs(stoneware)-work the cylinder up into a cone shape.Use less water

all general ideas here.

[Rex Johnson]

...what kind of clay? Is there grog or sand in it?

 

>>> http://community.ceramicartsdaily.org/topic/15275-pulling-walls/

[MatthewV]

Yeah, it is normal. 12" is pretty hard to get.

[Marcia Selsor]

Pull straight up for a few pulls and then neck it in a bit. Do some more straight pulls and neck it in again. Use a rib to get rid of any wonkiness. Don't use much water and sponge in off after putting it on. Pull up with your index finger knuckle on the outside. get the clay off the bottom when you open by curling your fingers along the bottom to creat a ridge in the inside giving you something to pull up.

.

.

Marcia

[glazenerd]

Preeta:

 

One of my practice exercises, is pouring one cup of water in a bowl to throw 12" cylinders with. I plan on doing mostly porcelain once I get some reasonable set of skills down. This forces me to use way less water: find myself just dipping my fingers into the bowl instead of sloshing on the water.

 

Nerd

[Marcia Selsor]

I always apply water with a sponge rather than fingers.

Marcia

[Mark C.]

Nerd

Yes use a sponge not fingers for wetting

[Pres]

Getting higher than 10-12" usually is a difficult barrier to break for inexperienced throwers. Most of the suggestions here will help with your problem, but I may add a few.

 

• Think about pulls as an amount of drag on the clay. Also understand that more water means more weakness in the vertical that you can get out of the clay. So part of your problem when throwing taller is two fold, lower the water to keep the form stronger to support the upper form, and lower the drag so that the pot does not get twisted in your pulling higher. I approach this by working with smaller contact points of my pulls. Inside hand only uses one finger against the side of the pot, outside hand much the same. I use the thumb and second finger to support and strengthen the pointer as my contact point outside, and the second and third finger supporting the pointer finger on the inside. Smaller contact, less drag. At the same time, slurry will help with drag without weakening the clay as much. However, I have found that I can throw pretty much dry without adding water after the form gets up to 10".
• Also of importance when throwing taller is how the base side walls are in relation to the rest of the cylinder. Cut one of your tallest cylinders in half, and look at how much weight is in the bottom inch of the form. If you end up trimming an immense amount off the bottom then you are leaving that area to thick. When throwing your prime directive at the first part of the pull is to get a substantial amount of clay out of the base into the wall of the pot-evenly. Then as you pull higher you thin the walls evenly going upward. All too often I have watched successful throwers leave much clay in the base that could add a few inches of height to the form. Many will internalize defensively, saying they don't worry about it as they will just trim it. I postulate, that if you learn to throw minimizing the amount in the base you will end up saving much more time over your time on the wheel.

 

 

I hope that my rants have given you pause to think about your throwing, and can help you break into 14" and beyond.

 

 

 

best,

Pres

[Magnolia Mud Research]

my first go rounds on throwing tall pots, ~12 inches, were disasters because I did not have enough clay.  a cylinder 10 cm inside diameter, 1 cm  bottom and 1 cm  walls takes a lot more clay than I had imagined when I had been using about half kilo to throw bowls 15 cm diameter by 8 cm tall and quarter cm thick walls and bottoms.  Taller takes thicker walls and the volume of clay is not linear with dimensions of a smaller pot.    Try using more clay, a lot more, get confident in making it to your height target with thick walls, then aim to make wall thinner with practice. 

 

to not make a non-grooved wall, either speedup the wheel, or slow down how fast you lift your hands.  reuse the water that runs off the pot and into the splash pan instead of water from your water bucket - and use only enough to keep your hands from sticking. 

 

 

LT

[What?]

Just to add in on the water application topic. I was at a recent Tom Coleman workshop and he was using a spray bottle to mist water on the cylinder for the final few pulls(for porcelain). I gave this a shot and it works well.

[preeta]

thanks Matthew that's good to know.

 

my stoneware definitely has legs. i would not be able to throw otherwise. i use several clays and they have different size of grog.

 

since i throw with very soft clay i do NOT use a lot of water. maybe i need to use slightly firmer clay.

 

marcia i do pull and collar because quite often i offcente the piece. 

 

the one thing i still am too afraid to do is create that bead of clay pushed out when pulling up.

 

glazenerd that is a great idea about measuring the water. usually i do measure my water by choosing the vessel i use for my water bucket which is good for 4 or 5 pieces. i like the one cup measurement..

 

marcia i just learnt using the sponge and i find i pull better with it. i am forced to collar as i tend to go out more. i know i have issues with pressure. i always have this point of weakness half way or 1/3 of way from bottom (some of my bowls look like post pregnancy bowls). now i've learnt how to move clay to fix that problem. before i was losing cylinders at that point and they'd look like shirt sleeve on my arm. i have not tried the 2 lbs 10 inches btw. i will have to wait till next semester to do that. 

 

Pres i welcome your rants happily and from others too. I really do appreciate the details. the explanations is what truly helps me. the inside hand. are you using the whole side of the pointer finger or just the tips? is it the whole finger tip or just the corner of the finger tip? do you pull this way when you've got about 9 inches?

 

a whole bunch of clay at the bottom used to be my problem last semester. so this semester i specifically paid a lot of attention to it. so i dont keep a significant amount of clay at the bottom. until another teacher actually put her hand on my hand and helped pull from the bottom i didnt realise the significant amount of pressure you need at the bottom of the bowl and cylinder.

 

Magnolia I remember a discussion here about throwing 12 inches with 3 pounds of clay. so i use 5 to 7 pounds.  I keep my walls a little thicker for shaping. I am just understanding the thickness of clay - by feel and how thick a pot should be. when i am throwing a bowl for instance little ones i like thin, but bigger ones i like a little thicker (personally i dont like thin big bowls). at leather hard stage i realize what i thought was thin was not that thin. 

 

i know i have pressure issues. because when i use the rib a lot of clay comes off on it. i have to stop midway and clean the rib and then move up. 

 

really i should just stick to 12 inches right now and get more confident and be able to do it more effortlessly. and really just concentrate on throwing just a cylinder and not the basis for a vase. and achieve 10 inches with 2 lbs of clay or 3lbs for 12 inches of clay. i am always getting the cylinder out of whack and fixing that. 

 

but through all of this i dont know how my cylinders are even walled with a little amount of clay at the bottom. i know because i've had more failures than successes and i've cut into all of them including a few successful ones.

[Pres]

the inside hand. are you using the whole side of the pointer finger or just the tips? is it the whole finger tip or just the corner of the finger tip? do you pull this way when you've got about 9 inches?

 

I use the tips of the fingers in both places, putting a little bit of a crook on the inside to keep from using the side of the finger. On the outside, the thumb tip rests in the the first joint of the pointer-supporting. The longer second finger is bent and either rests below the pointer shorter than the pointer, or is pushing against the pointer opposite the thumb on the outside of the first joint. When starting the pull, the side of the pointer is used to get to the very bottom of the cylinder at the wheel head-starting the pull, then as the pull moves upward the hand/pointer move to a position that is parallel to the whee head thus perpendicular to the cylinder with maybe a slight downward angle of 5-10 degrees.

 

 

best,

Pres

[preeta]

thanks Pres. one thing i am working on or at least trying to be mindful of is not releasing suddenly. i do that a lot. 

[SydneyGee]

I have been avoiding pulling my 8" cylinder recently because I have only been using recycled clay. At this point in the semester, it is very inconsistent and has no legs. I don't know who mixed this last batch, but it is like throwing putty! I tried with 3.5lbs last night and got a 9" cylinder after fighting it for nearly 20 minutes. I just kept pressing the bottom until it gave me the height I needed. It really does take a lot of pressure near the base to get it to go up.

 

I know that for me, if I used a different, stiffer clay I would have had a lot less of a problem, but hindsight is 20/20

[Dave K]

What do you mean by " legs"? How much clay should be necessary for a 12" cylinder with 4 1/2" to 5" base and pretty much straight up and down? I use stoneware and for the first time achieved 12" with 7 pounds of clay. I was pleased but suspect that is too heavy.

[Marcia Selsor]

"legs" you'll know it when you feel it. It is a body strength the doesn't clause...unlike porcelain.

Marcia

[SydneyGee]

What do you mean by " legs"? How much clay should be necessary for a 12" cylinder with 4 1/2" to 5" base and pretty much straight up and down? I use stoneware and for the first time achieved 12" with 7 pounds of clay. I was pleased but suspect that is too heavy.

 

Legs is a term I grafted from Mark C. I just describe it as how much you can screw around with it before it gives up and warps/collapses beyond repair. I pulled my 9" tall x 3" diameter with very soft, poor clay at about 4lbs. I am a beginner, so I would not know if that is still too much as I ended up trimming it a bunch while still wet. After all was said and done off the wheel it was about 2.5lbs, which was still quite heavy for what it looked like.

[Mark C.]

Legs is a term I learned in clay and glaze calculation class in collage taught by a couple of Alfred professors who taught at my collage.

It describes clay that can stand up tall when throwing-porcelain for example does not have much leg -but many stone wares do thats why its used to track throwing. It just throws better.

[preeta]

in a thread here a while ago i know it was a challenge to throw 12 inches with 3 lbs. and marcia sets 10 inches with 2 pounds with her students.  the reality is 2 lbs and 10 inches is a great way to understand and therefore have great control of your clay body. but as a student i would not try to make a functional 10 inch mug made with 2 lbs clay you need that extra give to help with centering and trimming. in our school (a community college) one professor says 1 1/4 to 1 1/2 lbs and whatever size you can make, another 2 pounds and 6 inches which is reasonable for a two year college i feel.

 

also the thin and heavy issue is something you have to work out yourself. i prefer vase forms a little heavier. i now find i prefer my bigger bowls to be a little thicker but my smaller bowls a little thinner. 

 

one of the hardest tasks i was given in my first ceramic class is to figure out the weight myself instead of being told what to do. i hated it at first. thought it was the most ridiculous thing i had been asked to do when i had no experience. but i learnt a lot from that. plus i have been lucky enough to hold professional potter ware. and have been shocked by what i expected. they were either heavier or lighter.

 

i have not been able to throw 12 inches with 3 pounds. i have tried a while back, but found it extremely difficult to keep the clay in control for height when it got so thin. my hands are still not steady enough to not whack it out. but i have discovered if i throw big amounts of clay (like 10 pounds) then it makes it much more easier for me to throw with 7 pounds of clay. i have more control. 

 

since cylinders have been so tough for me i've been focusing on the bowl form and getting a feel for stretching clay. so i've been able to pull 12 inches with 5 pounds of clay and make a giant bowl with very little trimming (it still havent come out of the bisque for me to assess if i like the thinness of the bowl or not). at first the only way i could reach 12 inches was with 7 lbs of clay. 

 

i am hoping my trials with the bowl will give me enough information to be able to start back on cylinders next spring more successfully. 

[Magnolia Mud Research]

I often use the 'recycle clay' at the school studio.  It is short, usually too wet, and sometimes a bit 'sticky', but it is a good 'warm up' clay and for exploring new forms and ideas.  The wetness of the clay limits how tall you can create an object without increasing the cross section of the clay.

N.B. All clays have a deformation strength; a cube of clay will hold it shape until the compression forces exceeds some value, then it deforms.

Recycle clay has a low deformation strength. That is why it is easy to center, move around, etc.

I make it work for me by throwing a a basic skeleton of a form that is thicker, shorter, narrower than what I am aiming for. I then remove all the outside and inside slip and take the bat off the wheel, set it aside, and work on something else for an hour. When I come back, a lot of the water has evaporated and the clay has more strength.  I then begin to increase the size by making it taller, wider, ... etc. by thinning the walls until I feel I am getting close to the limit - then I take it off and let it dry some more.   Large pieces may take several passes, small ones such as cups, and bowl, usually take only two passes through the wheel. 

Another warm up is to take a 'hunk' of recycle clay, throw it down on the bat and start to work it without water and without centering the clay.  Just use your hands, a rib, and the wheel speed to shape the 'hunk' into something interesting - make sculpture not a pot.  find the limits of the clay as it is and practice on recognizing when to stop just before the limit.  When you have become 'bored', put the recycle clay back in the recycle bucket, and make a pot with regular clay.  You will be surprised at how much you will learn by what Nils Lou called 'playing' with clay (The Play Book, ISBN-13: 9781426910678).

LT