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Wedging Vs Coning Up And Coning Down

coning up wedging

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#1 hershey8

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Posted 09 October 2013 - 07:17 PM

I have been told to cone my clay up and down on the wheel to get rid up air bubbles and to create equal density in clay. But isn't this what I am doing when I wedge my clay? Also, it seems like no matter how  thoroughly I wedge my clay, I may still have some bubbles residing in it. While I understand that they pose no "blow out" problem, they are still undesirable. It there a way to wedge that absolutely eliminates bubbles?



#2 Biglou13

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Posted 09 October 2013 - 07:47 PM

sorry but your wedging technique may be off. have some one more experienced observe you wedging

chances are your folding  clay over too much,   try to fold over less clay with each wedge./knead

there is recent post with cut and slam technique

i do a bit of that, rams head, and spiral wedging, along with cone up and down a few times, sure its prolly over kill but its part of my routine and it get me and my clay aligned. ad to gem me and my clay awake

there will be others that say it isint necessary

are you using commercial clay out of the bag?

 

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#3 Kohaku

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Posted 09 October 2013 - 08:32 PM

I'm a big fan of cut and slam for getting rid of bubbles. You can take a slagged mass of recycled clay with dog hairs in it, and it'll be throwable after 30-40 cycles.

 

I usually do a brief spiral wedge just to get the clay into shape.

 

Coning- for me- is mostly about centering and achieving allignment in the clay mass, not about getting rid of bubbles.


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#4 Marcia Selsor

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Posted 09 October 2013 - 09:55 PM

for me coning up and down gets the piece centered. I wedge to remove the air bubbles.
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#5 PSC

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Posted 10 October 2013 - 04:11 AM

Wedging is not folding the clay but stretching it so the bubbles burst, i prefer ram's head wedging, tip up the lump, stretch the backside of the lump as you roll it forward. Towering, coning, wheel wedging whatever you would like to call it removes any air bubbles you missed but it really prepares the lump into the right shape to center. I usually tower twice then complete my centering.

#6 TJR

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Posted 10 October 2013 - 07:44 AM

I'm a big fan of cut and slam for getting rid of bubbles. You can take a slagged mass of recycled clay with dog hairs in it, and it'll be throwable after 30-40 cycles.

 

I usually do a brief spiral wedge just to get the clay into shape.

 

Coning- for me- is mostly about centering and achieving allignment in the clay mass, not about getting rid of bubbles.

I am a big fan of cut and slap wedging as well. I own a very fierce poodle. They don't shed.

TJR.



#7 Pres

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Posted 10 October 2013 - 07:54 AM

I am still lucky enough to be able to wedge by hand decently, and do both the slash & slam, and cone wedging. For me it is around 100 turns at least for every piece of clay after slash & slam. If I am using the clay for handles, it is usually 200 turns, and a week of storage. As to the cone up and down, often called Mastering, I do this on the wheel to start the centering process, coning up and down about twice nothing here in the way of wedging, just getting feel of the clay. I really don't cone up and down when throwing over 10#, seems like a waste of energy.


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#8 timbo_heff

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Posted 10 October 2013 - 09:47 AM

Related: Coning up and pushing down properly: aka power wedging is the secret to never getting an s-crack.

Zamek did a nice paper on the subject. Even with the most finiky clay the power wedge prevents these pesky little devils: important to really engage the clay down at the bottom area of the cone:

I have seen really experienced throwers start to get s-cracks and think it is a clay problem, but always once they read this, they realize that with age and arthitis etc, they really are not engaging the clay in the coning process, especially down low, like they used to. I have never seen this not solve the problem.
Some clays are more prone to s-cracks, but this is a good thing to assimilate into one's practice even if s-cracks are not a problem (at the moment)

here's the paper:

http://www.sheffield...ng S Cracks.pdf



#9 JBaymore

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Posted 10 October 2013 - 10:29 AM

Very true, Tim.

 

best,

 

..............john


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#10 Kohaku

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Posted 10 October 2013 - 10:51 AM

Related: Coning up and pushing down properly: aka power wedging is the secret to never getting an s-crack.

Zamek did a nice paper on the subject. Even with the most finiky clay the power wedge prevents these pesky little devils: important to really engage the clay down at the bottom area of the cone:

I have seen really experienced throwers start to get s-cracks and think it is a clay problem, but always once they read this, they realize that with age and arthitis etc, they really are not engaging the clay in the coning process, especially down low, like they used to. I have never seen this not solve the problem.
Some clays are more prone to s-cracks, but this is a good thing to assimilate into one's practice even if s-cracks are not a problem (at the moment)

here's the paper:

http://www.sheffield...ng S Cracks.pdf

 

Great article. I wish I'd had this a year and a half ago when I was struggling with this issue.


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#11 JBaymore

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Posted 10 October 2013 - 11:10 AM

This is also why sprial wedging ("kikumomi" in Japanese) is superior to cut and slap wedging if you are going to throw off the hump.  The spiral wedged clay is put onto the wheelhead so as to orient the spiraling direction so that it alligns with the wheel axis.  Then there are a couple of little "tricks" that are used when opening the form on the hump that helps to minimize S cracks too.

 

best,

 

...............john

 

PS:  When I watch many people wedge using the spiral method.... I can see why it is so stressful on their wrists and lower arms.... they are not doing it correctly.  The wrist on the "power" arm should not break outward at the forearm very much at all.  This keeps the forces directed into the bones.... not putting the stress on the soft tissues.  And "power" is too strong a word there....... it is not about a lot of force.  It is actually somewhat gentle if you are doing it right.  Less is more.


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#12 Pres

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Posted 10 October 2013 - 04:26 PM

I can't understand the people that are perfectly healthy who chose to do spiral wedging or any wedging sitting down. I have never been a big person, but by standing and using my body weight in motion wedge successfully. When done properly spiral wedging does not use a lot of elbow or wrist movement. Most of my moves come from the shoulder and legs and the spine connecting them.


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#13 Sojourner

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Posted 10 October 2013 - 04:41 PM

I'm no longer young and hale but I STILL don't wedge sitting down - even given the difficulty I have standing.  I don't "wedge" the way most people do either.  I wire wedge, also known as "stack and slam"

 

http://ceramicartsda...rowing/?p=43358

 

There are videos and more explanation of wire wedging in that thread.



#14 hershey8

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Posted 10 October 2013 - 07:40 PM

Thank you all for the information on wedging and coning!  I guess i was hoping that wedging would eliminate the need for coning. That's because every time I try to cone up and down, I seem to get a twist and a lump or knot in the clay that I never get rid of. My clay is "out of the bag", but has set up for a couple of years. It tends to be cold and a little stiff, just like me.  I'm throwing on a homemade treadle mill that is less than perfect in design. It's tough getting the rpms (100-120). (My 2nd hand Brent C burned out a month ago, if you 're wondering why a treadle mill) All of this, plus my lack of experience, may add up to a potter's "perfect storm." 



#15 JBaymore

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Posted 10 October 2013 - 08:04 PM

I can't IMAGINE wedging sitting down.

 

best,

 

.............john


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#16 Mark C.

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Posted 10 October 2013 - 08:33 PM

Do yourself a favor and fix the Brent C wheel

as far as the old clay-open the bag and squeeze a sponge full of water and reseal-roll on each side and let it stay on that side for a few hours after 4 sides are done rebox and let sit a week-this clay will now not be hard anymore. Porcelain takes longer.

Bagged clay should have no air bubbles in it inless you are wegding them into it.

Mark


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#17 Pres

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Posted 10 October 2013 - 08:45 PM

One addendum to that Mark, if boxed/bagged clay has frozen, it will have air bubbles and be inconsistent.


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#18 TJR

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Posted 10 October 2013 - 09:05 PM

Hey,guys;

I guess I didn't give a complete answer.[Chris don't read this]

1.I never use clay straight out of the bag without wedging. Iuse Danish White clay from Laguna.

2.No matter how I try, even if I throw the same day I purchase clay, I find the clay too stiff out of the box.

3.I even ask specifically for soft clay.

4.Chris Campbell-stop reading at this point.

5.I always wedge my reclaim clay into my new clay, esp. if I am making flat ware like plates, or pie dishes.

6.I cut both clays into bread slice sections, then alternate them,using about one half reclaim.

7.I cut slap the whole mess for about 20 cuts, turning it a quarter turn each time.

8. I then spiral wedge in reasonable amounts. I no longer have to be macho-so I spiral wedge what I can handle.

9.I then weigh out my lumps of clay [almost said balls there]. If it is a 5pound plate I spiral wedge again, then throw.

10.I also cone on the wheel, but not excessively.

TJR.



#19 Biglou13

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Posted 10 October 2013 - 09:23 PM

Your wheel may be serviceable there a bunch o mechanical geniuses here especially when in come to potter mechanics.

One thing I love about this site. Is that we can extol the values of .....wedging clay....and understand the subtle nuances....I suppose that's what happen when there a experts in our midst.

Sure I do this almost ritual when wedging and throwing. But I have tell you. Before I could cone up I built hundreds of piece or so on rams horn style wedging and had only 2 s cracks.

Plus one on gentle wedging (especially spiral). I once wedged 80 plus pounds of clay in one session. Couldn't find tools open up pugmill. No longer fear wedging large quantities. I no longer desire a pug mill.

That whole solution to the crack thing , to me, is about compressing bottoms, throwing dry as possible and drying slowly and evenly. Not wedge and cone.

Do tell us about the home made treadle...... You'd be surprised how many treadle aficionados are out there.
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#20 Mark C.

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Posted 10 October 2013 - 10:02 PM

One addendum to that Mark, if boxed/bagged clay has frozen, it will have air bubbles and be inconsistent.

I thought about that but I did not think it froze in GA but it may?? Best to keep it from freezing.

On another note

If you drop your pug on each side hard theta also will soften it-this is an old timer trick-I slam each pug on all 4 sides while still in plastic bag (I throw 99% porcelain)Then open and cut to wieghts

Mark


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