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Does size matter?


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I'm looking to stimulate some conversation about the amount of clay one starts with as opposed to the weight of the finished pot.  For example, I usually make a standard sized mug out of a 15 ounce ball of clay but after trimming it weighs only about 9.5 to 10 oz.   This seems like a lot of waste even though when I throw it seems that I have stretched the clay to its limits.  Invariably however, when I trim I find a lot of extra clay at the bottom (actually at the heel where bottom and side meet) and that the sides can be significantly "shaved" thinner.

Is that normal or is this just the mark of a beginner potter? 

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Beginners often leave clay at the bottom. The more you throw the better you get at pulling  this up and ...... trimming it off in the throwing process. Anything less than 12oz of clay is so small I have difficulty throwing though so I have improved at throwing but also finishing so not much trimming is needed. Here is an old not so great video, but at the end you will see me pretrim what I couldnt get from the bottom  and cut the shape in half to get an idea of what is left to trim when green. https://youtu.be/49FBMLh3bKU

I am not a proficient thrower BTW but it might give you ideas.

Cut a few in half and see where you are leaving clay.

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As mentioned by @Bill Kielb, beginners leave a lot of clay in the base. That said, best advice is practice. While practicing make certain to get the pull started with a strong pressure between inside and outside pressure points, as you feel the clay start to rise, raise your pressure points, but let up slightly on your pressure. This will allow you to get the most out of the base, and to allow the walls further up the strength to not buckle. One simple way to concentrate on the feel is to throw with your eyes closed or blind folded. I have often demonstrated from beginning to end blnd folded for class demonstrations to show students that most of it is in the touch and feel of the clay, not the sight.

best,

Pres

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I used to believe myself rather an expert on transitioning from raw beginner to low intermediate level, on account o' that's where I'd just been. Now that transition is further back ...every day. Perhaps now I'm rather an expert on the very long transition from intermediate to advanced intermediate?

Any road, the web of clay at the wheel head - where the base of the wall is - will respond to pressure, as Pres points out. It takes quite a bit more time and pressure to get it moving (compared to up and away from the base) however, likely due to the stabilizing influence of wheel head contact and the base layer of clay. See Bill Van Gilder's throwing video clips - note how he uses his thumb and/or finger tips to manage the web. I use the side of my index finger to form an initial groove, then I'm turning same index finger to move the shoulder of clay up a bit (pointing down and in) afore beginning the pull - hence my fingernail is not touching the clay, nor the wheel head*.

Pulling walls, looks like lots of potters work a tapered profile, where the taper diminishes as the wall rises. Too thin or thick at bottom, middle, top, at each stage of the process, my guess is we each experience the several fail scenarios and learn, eh? 

I've found exploring "big" and "small" to be a good learning experience. "Big" for me is over 1200 grams or so, and "small" is throwing hollow knobs for jar/teapot lids and kiln filler bud vases. Big requires more patience, larger contact, and some adjustment on managing the taper; small requires a light touch, and fingertip contact with the clay. The overall process is about the same, methinks.

*fingernail wears away rather quickly, and doesn't grow back fast enough, hence, I'm learning to keep my fingernails off the moving clay when centering, opening, pulling, finishing.

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As your skill improves you will be able to make larger pots with less clay, which translates into less trimming. It's all part of the normal process for learning to throw. I used to make my mugs with 1.5 pounds, now I do them with 1.25 pounds. My students make mugs of the same size with 1.75 pounds.  Part of it is that mine are a bit thinner, but it's also that I don't have to trim as much- I'm able to get the clay up from the bottom better than they do.

I often have students that are making really nice forms, but they're really heavy. So I have them throw a cylinder and tell me when they think they're done pulling and ready to shape the piece. Then I have them pull it again, and again, and again, until the cylinder almost collapses from being too thin. They can always get at least 3 more pulls before they have to stop, and they're always shocked. They were just playing it too safe.

 Learning to pull without getting the top too thin  is very important. You have to ease off on the pressure as you move upward with your pulls. Otherwise the top gets too thin and unstable while there is still clay at the bottom that needs to be pulled up.

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another thing that helps is to start with the clay in the shape of a hockey puck and not a sloping mound.  raising what your finger gets under is easier if it is just going straight up and not sideways.  each pull must go all the way to the top of the clay to keep it from wobbling and at the same time the pressure decreases as the wall starts to become more even.  yeah, all that at the same time.

 i use a mirror to see the shape and watch the wobble and all the rest.   many people use a mirror to be sure the profile is correct all the way around and no lumps have developed.  the only person who thought i was using a mirror to see myself throw was a teenager with her appearance the most important thing for her.   others agreed that it was helpful to see how the pot looked and how raising the wall can be seen from a different perspective with a mirror.

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Another thing that is a factor for me is the clay body itself. I have a tendency to start wet, when centering, move quickly to drier, and then pull final stages with almost no water. I have gon through a lot of clay bodies looking for the clay that has a bit of tooth for touch, strength when stretched or otherwise abused, and able to work with my glazes that I like. It has taken me through many clays, of which I find SC 112 & 200 very good, SC 630 good,  and SC 211 quite good. I hand build and throw, so I like to have clays that will do both well. Each of these clays throw well for me with some adjustments to my style, but they will throw quite thin, will work well with faceting and stamping or other abuse before shaping and will hold up to extreme inflation of the form. 

So searching for the perfect clay for your processes is a step in your throwing advancement especially as you step from beginner to intermediate thrower. Another step is to expand your repertoire of forms, if you see something, learn to throw it. After learning the form, modify or improve it to make it your own. The more you analyze forms and understand their strengths and problems the better your throwing will become. Finally, never, never become too attached to one piece. . . it is only a step to something better. You have to be able to reject something that just does not seem right, or you know to be a mistake even though it may make you happy. There are fortunately happy mistakes, whether from the kiss of heat, the flash of a glaze fume or even a form that ripped but still stands well. 

best,

Pres 

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An exercise that I remember helped me really get weight out of the bottom of mugs was to start throwing larger pieces of clay, and make 3 or 5 lb serving bowls or jars, or pitchers, etc for a bit. It’s probably related to learning to apply more pressure, like Hulk mentions. When you go back down to the smaller pieces of clay to make a batch of mugs, you’ll find you get a lot more weight out of those corners.

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