Jump to content
Sign in to follow this  
hershey8

Wedging Vs Coning Up And Coning Down

Recommended Posts

hershey8    13

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?

Share this post


Link to post
Share on other sites
Biglou13    202

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?

 

welcome to the board.  tell us about yourself history with arts and ceramics and fill out profile

Share this post


Link to post
Share on other sites
Kohaku    22

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.

Share this post


Link to post
Share on other sites
PSC    54

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.

Share this post


Link to post
Share on other sites
TJR    359

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.

Share this post


Link to post
Share on other sites
Pres    896

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.

Share this post


Link to post
Share on other sites
timbo_heff    37

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-pottery.com/v/vspfiles/downloadables/Zamek-Preventing%20S%20Cracks.pdf

Share this post


Link to post
Share on other sites
Kohaku    22

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-pottery.com/v/vspfiles/downloadables/Zamek-Preventing%20S%20Cracks.pdf

 

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

Share this post


Link to post
Share on other sites
JBaymore    1,432

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.

Share this post


Link to post
Share on other sites
Pres    896

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.

Share this post


Link to post
Share on other sites
Pyewackette    1

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://ceramicartsdaily.org/community/topic/4801-wrist-brace-when-wedgingthrowing/?p=43358

 

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

Share this post


Link to post
Share on other sites
hershey8    13

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." 

Share this post


Link to post
Share on other sites
Mark C.    1,807

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

Share this post


Link to post
Share on other sites
Pres    896

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

Share this post


Link to post
Share on other sites
TJR    359

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.

Share this post


Link to post
Share on other sites
Biglou13    202

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.

Share this post


Link to post
Share on other sites
Mark C.    1,807

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

Share this post


Link to post
Share on other sites
Benzine    610

I have only recently started to cone up, when throwing.  It just wasn't taught to me, though I did come across the process quite a bit elsewhere.  So I finally broke down, and decided to see what the fuss was all about. 

I honestly haven't found there to be a difference in the end product. 

 

In regards to avoiding the dreaded "S-Crack" I have found taking a wood rib to the bottom, for compression, works quite well. 

 

I will say, it is a good way to get a feel for the clay, and does help center though.

Share this post


Link to post
Share on other sites
Mark C.    1,807

Coning up and down is for me way to center that I have done since 1969 when I was exposed to the wheel .

I do not do it for small clay amounts only larger forms.

Mark

Share this post


Link to post
Share on other sites
yedrow    8

I pug the clay and then cone up and down two times for anything over 2 pounds. This takes care of cracks. Good handling after drying is important too. A well designed clay will actually tolerate a lot, as long as you don't break certain rules. A poorly designed clay though will impose itself upon your work.

 

Joel.

Share this post


Link to post
Share on other sites
PotterGrl    3

You already have all the advise you could possibly need ;o)  For me, I do rams head wedging and have never had an issue with it. I try the spiral now and again just because I want to be able to do it, so far my hands/brain haven't figured it out ;o) Simon Leach has a great video where he teaches the spiral wedging process, I need to go look at that again. He also teaches the wire cut and slap process. Look up his videos and search within his videos, wonderful stuff.

 

I only wedge standing up. I'm 5'3" and 115lbs, I need all the weight/height I can get behind my wedging ;o) 

 

I never used to cone up simply because I couldn't. I never had an issue, probably because after I open up, I compress the bottom well before I even pull up. Now I do cone, but only a little bit. From what I understand, it's purpose is compression of the clay and help centering. I will say, I think it does help center. I don't do the tall coning like you see some people do, but it seems coning does help the centering. I now center like a pro! I've never had lumps in my clay, unless the clay just isn't mixed well. I don't think coning has anything to do with that. My pottery teacher, who has been doing this for nearly 40 years, throws her bags of clay  on the floor many times before using. Maybe once per side or even more if she can tell it's stiff clay. 

Share this post


Link to post
Share on other sites
Davidpotter    8

i spiral wedge and then cone. since i do most of my throwing at school we don't always have perfectly soft clay so i will usually cone a bit for more dry pieces. But i mostly use coning for centering. plus now its just automatic for me. It does help you find non clay pieces though if you are in a class full of careless people throwing whatever is in their bucket into the pug mill. ribs, sponges, fired clay pieces, needle tools (yes it hurts to find needle tools while centering) etc.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×