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#1 Kohaku

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Posted 17 October 2012 - 04:51 PM

OK- first off, I feel like I've been posting a lot in the last few days. I hope you'll all forgive me! I'm new to the forum, and realizing that there are tons of technical questions I'd like to pitch... but I'll try to restrain myself.

Anyhow, the one form that continues to challenge me on the wheel is the elongated cylinder.

As an example- I'm currently working on a project involving a range of percussion instruments. One of my goals is to make a Engalabi-style drum. These things should ideally be about 3-4 feet high, with a narrow diameter. Here's one of my recent efforts- see the photo at the base of the post (pardon the elongation). Three feet in height- barely fits my raku kiln

So- I've been finding these forms to be brutally finicky to throw in one shot. No matter how well I wedge/prepare my clay, and no matter how meticulously I center, there always seems to be some irregularity walls as I open. These (miniscule) irregularities tend to lead to vicious wobbles near the top- especially as I try to thin the walls at the base.

I've shifted to building these tall, slender forms from sections... but this seems to increase my rates of failure during raku firing (note- I join the sections with a scored, beveled lip, using magic water). The drum in the picture shattered into scraps upon removal from the kiln- you could hear me swearing for miles.

So- a couple questions...

1) is there a height-diameter combo beyond which most people won't push their work (thrown in one piece)?

2) Alternately, is it just a matter of gaining practice and experience with these larger, tall forms? (Note- I'm pretty fluid with most other forms).

3) If #2, are there any technical suggestions for maintaining evenness as you lift the sides into the wobble zone?

Much obliged.

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#2 voceramics

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Posted 17 October 2012 - 05:15 PM

I've seen photographs of tall cylinder forms being thrown in Korea. Instead of pulling the wall up to create their form, they center and work a very tall mound of clay and then they throw the walls, hollowing it out while working downward. They get their whole arm in there and some of the forms are so tall they use a stick with a nob at the end to finish the bottom.

I don't throw, so am probably using the wrong terminology. But the photographs were from a very old Ceramics Monthly article.

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#3 OffCenter

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Posted 17 October 2012 - 05:33 PM

1) There's no reason to set any limits. The clay and your throwing skill will set the limit. Just keep throwing. Many people use clay that is too wet. Usually the stuff that comes out of the bag (if you buy commercial clay) is way too wet. It should be as hard as you can work with without defeating the purpose of using hard clay by using too much water to center and pull it. Avoid building a pot in sections. Sometimes you may have to make something like a gigantic jar in two or even three sections but for what you're doing you should throw it in one section. It's hard to get a strong, gestural form when you build it in sections. For example, the bottom two-thirds of the pot pictured is a nice, strong shape that is completely ruined by the lumpy, ugly top part.

2) Yes. The slightly concave cylinder is the easiest form to pull tall. I can't tell how tall it is or high thick the walls, but the bottom section of the pot pictured looks like you know what you're doing and you're "pretty fluid" with that form.

3) Throw hard but not too hard clay and maybe add a little grog if there isn't any and keep the sides of the cylinder slightly concave. If you don't want the finished cylinder concave wait to straighten the sides until after you've got the height you want. All you need is a little more practice.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#4 Kohaku

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Posted 17 October 2012 - 05:50 PM

1) There's no reason to set any limits. The clay and your throwing skill will set the limit. Just keep throwing. Many people use clay that is too wet. Usually the stuff that comes out of the bag (if you buy commercial clay) is way too wet. It should be as hard as you can work with without defeating the purpose of using hard clay by using too much water to center and pull it. Avoid building a pot in sections. Sometimes you may have to make something like a gigantic jar in two or even three sections but for what you're doing you should throw it in one section. It's hard to get a strong, gestural form when you build it in sections. For example, the bottom two-thirds of the pot pictured is a nice, strong shape that is completely ruined by the lumpy, ugly top part.

2) Yes. The slightly concave cylinder is the easiest form to pull tall. I can't tell how tall it is or high thick the walls, but the bottom section of the pot pictured looks like you know what you're doing and you're "pretty fluid" with that form.

3) Throw hard but not too hard clay and maybe add a little grog if there isn't any and keep the sides of the cylinder slightly concave. If you don't want the finished cylinder concave wait to straighten the sides until after you've got the height you want. All you need is a little more practice.

Jim


Cheers!

BTW (and in my defense) the lumpy ugly top part is a replication of the tops of a couple carved Engalabis that I checked out in a museum. I may have been too literal though... just because it's trad doesn't mean it's aesthetically pleasing...
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#5 OffCenter

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Posted 17 October 2012 - 07:01 PM


1) There's no reason to set any limits. The clay and your throwing skill will set the limit. Just keep throwing. Many people use clay that is too wet. Usually the stuff that comes out of the bag (if you buy commercial clay) is way too wet. It should be as hard as you can work with without defeating the purpose of using hard clay by using too much water to center and pull it. Avoid building a pot in sections. Sometimes you may have to make something like a gigantic jar in two or even three sections but for what you're doing you should throw it in one section. It's hard to get a strong, gestural form when you build it in sections. For example, the bottom two-thirds of the pot pictured is a nice, strong shape that is completely ruined by the lumpy, ugly top part.

2) Yes. The slightly concave cylinder is the easiest form to pull tall. I can't tell how tall it is or high thick the walls, but the bottom section of the pot pictured looks like you know what you're doing and you're "pretty fluid" with that form.

3) Throw hard but not too hard clay and maybe add a little grog if there isn't any and keep the sides of the cylinder slightly concave. If you don't want the finished cylinder concave wait to straighten the sides until after you've got the height you want. All you need is a little more practice.

Jim


Cheers!

BTW (and in my defense) the lumpy ugly top part is a replication of the tops of a couple carved Engalabis that I checked out in a museum. I may have been too literal though... just because it's trad doesn't mean it's aesthetically pleasing...


I looked up Engalabis drums and now see what you're trying to do. A wide bowl shape on top of the concave cylinder is a lot harder to throw than just the cylinder alone so maybe two pieces is necessary. But what you have isn't as much of a bowl as the examples I saw and I think it would look much better in one piece. BTW, the decoration on the bottom part is nice. I'm looking forward to seeing a finished drum.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#6 OffCenter

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Posted 17 October 2012 - 07:04 PM

I've seen photographs of tall cylinder forms being thrown in Korea. Instead of pulling the wall up to create their form, they center and work a very tall mound of clay and then they throw the walls, hollowing it out while working downward. They get their whole arm in there and some of the forms are so tall they use a stick with a nob at the end to finish the bottom.


Strange way to "pull" a cylinder but interesting. I'd like see that being done or even just the finished pot.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#7 Kohaku

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Posted 17 October 2012 - 07:42 PM

I looked up Engalabis drums and now see what you're trying to do. A wide bowl shape on top of the concave cylinder is a lot harder to throw than just the cylinder alone so maybe two pieces is necessary. But what you have isn't as much of a bowl as the examples I saw and I think it would look much better in one piece. BTW, the decoration on the bottom part is nice. I'm looking forward to seeing a finished drum.

Jim


I agree- and will probably go that route on the next one.

Realistically thought- isn't the practical limit on height (without joining) close to the length of ones arm? The piece in the photo above was a bit over three feet, and I had my arm in the cylinder up to my armpit while throwing the bottom section. Maybe there are ways to extend this through pulling up a volume of clay early, or through using throwing sticks as mentioned above.

Here's a drum that worked- part of the same series. A modest half meter in height.

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#8 yedrow

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Posted 17 October 2012 - 11:12 PM

A few years ago I saw a guy throw a tall cylinder by lifting it to a respectable height, then drying it a little with a torch (while the wheel turned) then lifting the thinner dryer clay to completion. Also, some clay is poorly formulated and some is well formulated. Standard clay out of Pennsylvania makes a body that almost seems to throw itself. I throw a lot of clay and in my opinion most bodies I've used are like garage recipes. There is nothing nicer than a good performing clay, especially if it keeps you from ruining your body to make a living.

Joel.

#9 Lucille Oka

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Posted 18 October 2012 - 01:28 AM

I wonder how the drum would sound if the clay was vitrified. Why do you raku this vessel? For the sound? Completion speed?
But this is beside the point take a look at Scott Semple-
http://www.skutt.com...emple/index.php maybe his work can give you ideas. I hope it helps.



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#10 OffCenter

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Posted 18 October 2012 - 09:18 AM

I agree- and will probably go that route on the next one.

Realistically thought- isn't the practical limit on height (without joining) close to the length of ones arm? The piece in the photo above was a bit over three feet, and I had my arm in the cylinder up to my armpit while throwing the bottom section. Maybe there are ways to extend this through pulling up a volume of clay early, or through using throwing sticks as mentioned above.


When I throw tall, narrow bottles (there are pics on my profile page) and I'm up to my armpit in clay I know that this pull will be the last time I'll be able to pull the bottom 6 inches or so, so I pull that part accordingly. The next pull will start about 6 or so inches above the bottom. Also, I usually use a heat gun to dry that bottom part that I can't reach anymore enough so that I don't have to worry about it collapsing.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#11 Marc McMillan

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Posted 18 October 2012 - 09:31 AM

Throwing that tall is beyond my skillset, but I haven't had a need to do it.

However, one small thing to check is how level your wheel is. I read that on here and found I had placed the wheel on ground that wasn't level. A bit of shimming helped it out and made taller forms easier.

Good luck.
Marc

#12 Cass

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Posted 18 October 2012 - 09:37 AM

the basis for my tall throwing technique is an article ten years ago or so, in either CM or pottery making illustrated, callled "Going Tall" you migh tbe able to find it

basically you leave a ring of greater thickness at the middle height of the wall on the inside, and are regulary collaring the piece inward and upward....last step is to pull that ring up to an even thickness with the rest of the wall

the simple drawings in that article make it so clear, but that is the concept, you'll be arm deep before you know it

#13 Kohaku

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Posted 18 October 2012 - 10:31 AM

I wonder how the drum would sound if the clay was vitrified. Why do you raku this vessel? For the sound? Completion speed?
But this is beside the point take a look at Scott Semple-
http://www.skutt.com...emple/index.php maybe his work can give you ideas. I hope it helps.


Great video. He's going the sectional route though. I've already had some success with this, but it seems to increase failure rates during the Raku process. In terms of 'why Raku'... for much of my work, and for this series specifically, I use a 'raku-mosaic' technique (multiple glazes within carved lines, lines blackened by the firing process). See the rhino drum above for an example. I don't know of any way to duplicate this surface using hi-fire. Also- while hi-fired pieces might be stronger, I'd worry that the full vitrification would give more of a bell-like tone... not necessarily a good thing in a drum.

the basis for my tall throwing technique is an article ten years ago or so, in either CM or pottery making illustrated, callled "Going Tall" you migh tbe able to find it

basically you leave a ring of greater thickness at the middle height of the wall on the inside, and are regulary collaring the piece inward and upward....last step is to pull that ring up to an even thickness with the rest of the wall

the simple drawings in that article make it so clear, but that is the concept, you'll be arm deep before you know it


Thanks- I'll look for this.
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#14 pricklypotter

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Posted 18 October 2012 - 10:54 AM

Another technical idea that works better, for maintaining fluidity of form, than 'sectional' pots (i heard this is how ming vases were made):

throw the bottom, leave the rim thicker than you want, get to leather hard.

now centre more clay and open to the wheelhead, making a fat coil that would sit on the rim of the leather hard pot. score and slip the rim of the leatherhard pot, recentre the pot on the wheelhead (a plastic batt would work) and attach the coil. throwing the very bottom of the coil down a bit helps strengthen the joint. now keep throwing the coil up, with slurry instead of just water so it doesn't wet too much of the leather hard pot underneath it.

you can reach a very organic, seamless shape this way. if the joint bulges a bit you can scrape it away with a serrated rib and smooth it after. cover, with a fabric under the plastic to even out the moisture, and, in principle, when the top is leather hard, repeat ad infinitum.

the only caution is not to do it just over a very abrupt change in the curvature of the pot.

i don't make very tall stuff but i raku fired thin porcelain goblets this made this way and they didn't explode.

#15 yedrow

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Posted 18 October 2012 - 09:18 PM

It's hard to get a strong, gestural form when you build it in sections. For example, the bottom two-thirds of the pot pictured is a nice, strong shape that is completely ruined by the lumpy, ugly top part.
Jim


I forgot; this is a very good point. I'm working on learning how to throw in sections. But both in execution and observation of others, it seems to be that the form suffers greatly when objects are thrown in sections.

Joel.

#16 Pres

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Posted 19 October 2012 - 08:49 AM


It's hard to get a strong, gestural form when you build it in sections. For example, the bottom two-thirds of the pot pictured is a nice, strong shape that is completely ruined by the lumpy, ugly top part.
Jim


I forgot; this is a very good point. I'm working on learning how to throw in sections. But both in execution and observation of others, it seems to be that the form suffers greatly when objects are thrown in sections.

Joel.


A few thoughts here. When looking at your form above, it seems it was thrown in 3 sections due to the bulges. Whether or not, I would recommend a little more ribbing to unify the curves, and help to strengthen the joins. At the same time throwing sectional forms will get you nice cylinders, but you really need to have firm control for the heights you are aiming at. As others have said make certain your wheel is level. The magic water is a great sub for the slip, but try to work more of the clay out of the joins by pulling from below the join to above a few more times.

Raku? I wonder if you could fire your bisque a little higher, and then fire the raku. This may help with the survivability. Other thought is how the heck are you getting these out of the kiln at that size? Heh Heh!

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#17 Kohaku

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Posted 19 October 2012 - 09:49 AM

Everyone- I really appreciate all of the feedback- very helpful.

Pres et. al. - your comments definitely jibe with my experiences with building in sections. In actuality, the tall piece I posted was thrown in two sections (top goblet section, bottom cylinder)- you can see the join midway. I had to extend my raku kiln base using some firebrick.

Here are a couple of pieces I threw yesterday- a bit smaller (two feet) but also thrown in sections. It seems to work a bit better if you do your joining at a natural break point. I'm still worried that these will fracture, however. I did make and extra effort to work vertically from the join, basically 're-throwing' the point of connection. Note- I deviated from the traditional Engalabi shape a bit.

I think my next move will be to try a couple using the coil-based method that PricklyPotter mentioned. I've never tried that approach, but it seems intriguing.

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#18 JBaymore

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Posted 19 October 2012 - 10:49 AM


I've seen photographs of tall cylinder forms being thrown in Korea. Instead of pulling the wall up to create their form, they center and work a very tall mound of clay and then they throw the walls, hollowing it out while working downward. They get their whole arm in there and some of the forms are so tall they use a stick with a nob at the end to finish the bottom.


Strange way to "pull" a cylinder but interesting. I'd like see that being done or even just the finished pot.

Jim




Jim,



Very common technique in Japan, Korea and China. Helps when the clay being used is not all that plastic like what we are used to in America. I use it and similar "not usually demoed in America" techniques sometimes for specific ends.

best,

..............john
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#19 Cass

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Posted 19 October 2012 - 03:04 PM

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nice drum forms!...i never have to many problems rakuing sectional forms, depends on the body, but larger stuff like this i bag for a week+, then dry slowly, taking the bag for a few hours, then covering overnight, the slower the better imo

throwing that joint up and down is good too, i sometimes force a thin coil into the join, work that all up and down

a friend in CA made some really nice raku drums, i dont know how he did it but he would get the head on with no visible connections, the skin just tucked perfectly into a thin groove he had formed in, about 1/2 inch down from the top edge, maybe wire or something bound around, but invisible, i forget..anyway, cool drums, any audio online?

#20 JBaymore

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Posted 19 October 2012 - 03:33 PM

One more technique you might never have seen or heard of for throwing larger forms ............

Center a large amount of clay on the wheel in a tall-ish configuration. This should be a weight of clay that will be appriopriate for the entire thng you intend to make. It will still be way shorter than the eventual finished product, but it should be centered well taller than it is wide.

Open up the clay about 2/3 to 3/4 of the way down to to the wheelhead. You are leaving the botton "massively" thick compared to all usual techniques. This is deliberate.

Starting at the point the inside opened floor now is, pull up and form the cylindrical form to the thickness that you feel is appropriate for the given form you asre making. And generally shape this form so that the part now near your eyes is the way you want the BOTTOM to look. (Yeah... the form is currently sitting upside down!)

Cut the piece off the wheelhead and set this aside so that the (current) TOP stiffens to leatherhard-ish. Depending on the weather conditions you might have to wrap the lower thick section with some plastic to keep THAT part from drying too much. But because it is thick and solid and base-down.... it will dry WAY slower than the hollow top part. Let it stiffen up til the top will well support the weight of the bottom. No more than that.

Then, using some clay for a nesting chuck to support and adhere the partially finished piece (not a Giffin Grip! :lol: ), invert the partially dry form back on the wheel in the opposite position to the way it was originally thrown (what was up is now down).

Like pretty much normal, open the thick still wet clay at the top through into the open area of the lower form. Pull up the walls from the juncture with the stiffer clay. By repeatedly wetting the area where the transition from leather hard and wetter clay happens you can re-soften this area a tad and facilitate some continued shaping at the juncture.

A bit of practice with this and you'll wonder why you did not think of it.

So the form is now thrown all in once piece...... just not all at one time. ;)

best,

................john
John Baymore
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Professor of Ceramics; New Hampshire Insitute of Art

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