Help! Always getting air bubbles at the base of my clay when centering.

[Finn Ewins]

Need a bit of help please. I have been doing pottery for a bit over a year now and picked up centering fairly quickly and never really had any problems. I’ve been using the pottery wheel at my college.

I recently bought my own pottery wheel for home (Brent Model C) and now all of a sudden I can’t seem to center my clay.

I use the same technique but for some reason on my new wheel the base of my clay is always off-center / feels like there is an air bubble trapped. 

I make sure I wedge my clay enough and the right technique and i also make sure that I don’t trap any air when throwing the ball of clay onto the wheel head. 
Anyone got any ideas what might be happening?

Thanks,

Finn

[Pres]

@Finn EwinsDo I assume that you learned on a wheel at a center or a friend/mentor? If so you may have problems adjusting to the height of wheel head on your second problem; not centering well.

As to the wedging, and throwing, you are working in a new area, at home I assume. If so is the height of your wedging area the same height as where you are used to working? Sometimes a lower or higher table height effects how you are wedging. For myself when I set up my wedging table, I measured the height of the table with a ball of clay around 10#s on it and the length of my arms to reach that ball of clay. Then I built my table to those dimensions maybe an inch or so higher. You arms should be relaxed and resting on the clay with just a slight bend in the elbows. Most of the motion for wedging comes from the body movement, not the arms. A properly setup table height will allow you to use your body most efficiently.

Hope this helps.

 

best,

Pres

[Finn Ewins]

Hi, thanks for such a quick reply.

Thankyou for your advice, I will try and adjust my seat height and see if that makes a difference.

As for the wedging, I am now wedging on the floor so that could be a problem. However even when I slice through the clay after wedging, I can see no bubbles.  

Thanks again, I will try out all your advice.

Finn

[Bill Kielb]

1 hour ago, Finn Ewins said:

I use the same technique but for some reason on my new wheel the base of my clay is always off-center / feels like there is an air bubble trapped. 

The obvious question - is there an air bubble trapped? Cut it off the wheel and look at different stages of centering. To avoid this I have formed a habit of rounding the clay into a ball, then setting it in place on the wheel head. A couple taps and seal the bottom to the wheel head ensured no air could be trapped and no clay leaving the wheel head unexpectedly. For some students, this technique seems to work well for them.

To see this simple technique, it is used each time a new ball of clay is set on the wheel. https://youtu.be/jVNJELUpclk

You may find it helps with centering and trapped air.

 

[Babs]

2 hours ago, Finn Ewins said:

Need a bit of help please. I have been doing pottery for a bit over a year now and picked up centering fairly quickly and never really had any problems. I’ve been using the pottery wheel at my college.

I recently bought my own pottery wheel for home (Brent Model C) and now all of a sudden I can’t seem to center my clay.

I use the same technique but for some reason on my new wheel the base of my clay is always off-center / feels like there is an air bubble trapped. 

I make sure I wedge my clay enough and the right technique and i also make sure that I don’t trap any air when throwing the ball of clay onto the wheel head. 
Anyone got any ideas what might be happening?

Thanks,

Finn

Is your wheel head level? Is the wheel level?

Do you cone your clay a couple of times before settling into opening the clay?

It is possible to trap air when coning down if not applying the correct pressure.

Compression of base  when you initially open out the clay.

Any bubbles can be popped successfully at this point.

Trim off the off centred but, slice thriugh with wire to check whether that area is thinner, or not. 

 

 

[Finn Ewins]

1 hour ago, Bill Kielb said:

The obvious question - is there an air bubble trapped? Cut it off the wheel and look at different stages of centering. To avoid this I have formed a habit of rounding the clay into a ball, then setting it in place on the wheel head. A couple taps and seal the bottom to the wheel head ensured no air could be trapped and no clay leaving the wheel head unexpectedly. For some students, this technique seems to work well for them.

To see this simple technique, it is used each time a new ball of clay is set on the wheel. https://youtu.be/jVNJELUpclk

You may find it helps with centering and trapped air.

 

Thankyou, I will use your advice and do some trial and error and see where I am going wrong. Much Appreciated.

Finn

[Finn Ewins]

1 hour ago, Babs said:

Is your wheel head level? Is the wheel level?

Do you cone your clay a couple of times before settling into opening the clay?

It is possible to trap air when coning down if not applying the correct pressure.

Compression of base  when you initially open out the clay.

Any bubbles can be popped successfully at this point.

Trim off the off centred but, slice thriugh with wire to check whether that area is thinner, or not. 

 

 

Hi, thanks for your reply.

Could you please let me know more precisely how one might make sure not to trap air when coning down? It is quite easy to trap air if coned down incorrectly?

Thanks

[Babs]

13 minutes ago, Finn Ewins said:

Hi, thanks for your reply.

Could you please let me know more precisely how one might make sure not to trap air when coning down? It is quite easy to trap air if coned down incorrectly?

Thanks

Ha! Make sure your hand moves down in the conung motion and pressure is maintained by small finger side of hand right down to wheel head and that the clay is shaped into a good clean shape to the wheelhead, no sloppy loose connection vetween wheelhead and clay. Some folk make a slightly mushroom shape .

Check out some videos of folk coning down

[Bill Kielb]

 

46 minutes ago, Finn Ewins said:

Could you please let me know more precisely how one might make sure not to trap air when coning down?

Mushroom top.   - no volcanoes with a hole in the middle of the top.

Edited August 8, 2022 by Bill Kielb

[Pres]

Coning the clay wedges it on the wheel somewhat. Pressure from the left hand at the base of the wheel is greater than the pressure on the right hand pushing down on the clay. When coning up, be careful to keep pressure even across the clay with the palm of the hands. It takes practice not to rip the cone in half, but is a good exercise for centering. Do the cone up and down about 3 times and you should end up with a pretty homogenous well centered cone of clay, almost like a bucket hat with sloped side inward.

You are right not to go any further until you have mastered the centering on your new wheel.

 

best,

Pres 

[Finn Ewins]

Hi all,

I have tried all your advice and I’m afraid to no avail.

I have however ruled out the air bubble problem as i cut through the clay after trying to center it and there are no air bubbles whatsoever throughout the entire ball of clay.

I used a spirit level on my wheel head and it is between the ‘level lines’ but slightly, very ever so slightly leaning to the left. Could this really be a problem?

Any other suggestions?

Thanks

 

 

[Bill Kielb]

8 minutes ago, Finn Ewins said:

I used a spirit level on my wheel head and it is between the ‘level lines’ but slightly, very ever so slightly leaning to the left. Could this really be a problem?

Any other suggestions?

Leveling should Not have an effect especially if you are already reasonably level. Somewhere there is a video of someone throwing a pot on a wheel that is very tilted just to show slight variations are not an issue.

If your wheel changes speed slightly throughout or your wheel head wobbles however this can make things very difficult.

First - Have you been able to get anything centered, maybe smallish softer clay? Has anyone else tried on this wheel and also cannot get things centered?

 

[Finn Ewins]

It’s a brand new wheel so I can’t imagine that it changes speed.

I don’t know anyone else who does pottery and can already center so I can’t figure out whether it’s me or the wheel.

[LinR]

Are you sure that the bottom of the ball of clay is well rounded when you apply it to the wheel?  I used to get air trapped under the clay when applying it to the wheel.  That wouldn't show by cutting through but it sure throws the clay off.

Are you hooking your left elbow into your body so that hand is very steady?

Lin

[Bill Kielb]

39 minutes ago, Finn Ewins said:

I don’t know anyone else who does pottery and can already center so I can’t figure out whether it’s me or the wheel

No worries, there are folks here that likely can help. So first, can you center a small amount of clay, maybe a pound without coning it up?  Maybe just using the gum drop shaped method and the outside edge of your hand. Sort of like a karate chop position? And I will add, if you have been taught to center at the highest speed, can you slow things down a bit and get the gum drop centered a bit more easily?

Edited August 9, 2022 by Bill Kielb

[Babs]

+1 with Bill.

Prepare 12 small balls of clay.

Centre without coning. Check your key points.

Seat close to and level with wheelhead.

Elbows anchored, hands working together at all times.

Your hands need to be working  about position "5 on the wheel clock"

Be aware how your hands leave the pot after each pull.

Clean the area where clay meets the wheelhead anytime it gets any gunk collecting.

Throw  12 cylinders.

Cut them through cylinders to check.

 

https://youtu.be/7lllCkLbJFE

Beware of the buttress one potter said... in these forums. It id a thick area which can cause probs..it occurs if clay is not picked up right where the clay meets the wheel head.

Maybe pics of your offcentre pots, or watch a video of yourself working.

Keep at it, observing the key points.

This frustration will pass..pottery life is full  of them, join the mob!

Edited August 9, 2022 by Babs

[Callie Beller Diesel]

@Finn Ewinsdo you by any chance have an Instagram or other suitable social media platform you could post a video on of what you’re doing? We could help you troubleshoot from that. 

The software that hosts the forum doesn't have the space for everyone to post video, so we need an outside link of some kind.

[Hulk]

Hi Finn!

Hope your centering gets sorted to the point where you are so focused on next/new challenges that you're able to almost forget centering*.

Some thoughts:

i) Consistent
Any inconsistency in the clay, whether bubbles, bits, chunks, drier spots, wetter spots, sticks, lumps, anything that causes the flow of the clay to speed up or slow down will make centering more difficult!
When worked on the wheel, the clay is flowing/moving in the opposite direction of the wheel. The clay flows, in a circle.
The clay accumulates where it slows down and thins where it speeds up - both throw centering off, boom.

Give yourself a good chance at the start, where clay is totally mixed/wedged/homogenous with no contaminants.
From there, try putting your well-prepared clay balls in a container to slow down any drying that may occur whilst waiting turn on the wheel, for a bit dry on one side or the top can "throw" you off.

Inconsistent clay can be forced into center, or close, but the problems will just present as you throw, with inconsistent wall thickness, varying wall heights, or both, leading to arrrg! ...tearing, lumpy, wobbly

Consistent clay leads to easy centering, round and even walls, amazingly round, even, easy.
Really.

ii) Attach well to the bat or wheel head.
When the clay moves, that definitely throws centering off!!
Might as well explore and discover this. When your clay ball is getting close to center, then apply centering force to the point where the clay moves - disengages from the bat.
Learn that boundry, then stay away from it. They type of surface makes a difference - rough, smooth, how damp, etc. Some clays stick better than others as well.
Softer clay is more responsive to centering force.
Firmer clay requires more patience, A Lot more patience!!

iii) clay
Are you using the same exact clay as available at school?
Each clay is a bit different, and how soft/firm** makes a difference as well.
Perhaps like riding a bike - when you've only ridden One bike, every other bike is like, wow, totally different.
When you've ridden many different bikes, you can adapt right away to a different bike.
:|

 

*Almost, for the same problems can and will rush right back, difference being you might recognize the cause right away vs. struggle.

**Softer clay centers quicker and easier, imo, and throws faster and easier as well.
On the other hand, the amount of working time (wetted time) afore it gets too wet is less.

Harder clay requires more patience, time, and force to center and throw, however, one might get taller and thinner.
:)
Harder clay seems less forgiving.

 

[Hulk]

Ooh yeah, forgot to add this:

The layer of clay right up against the bat (or wheel head) can't move the same as the clay above it, hence, if there's inconsistent bits in that layer, no amount of coning up/down will sort it, start over.

While I believe "wedging on the wheel" (aka coning up and down) is very important, it can't be a complete replacement for preparing the clay afore putting it on the bat.

[PeterH]

Do you still have access to the clay and wheel at college?

If so might be worth trying home clay wedged at home on the college wheel, and vice versa. It might at least remove some variables.

... and carefully consider any differences in body/arms/wheel/chair relationships in the two situations.

[Babs]

@Finn Ewins after being totally mesmerised by Neil's throwing ability, check carefully the totally stable base he provides for his hands.

Seat, knees , elbows, hands working together, even raising his heels to maintaining these anchor points.

Those points need checking until second nature as with Neil.

Lucky to have him as a moderator, hey?

[Tova Cooper]

I have been having this exact same problem! 

I am a very experienced potter, but for some reason after taking a break and returning (to a new wheel, in my garage), I keep getting air bubbles in the bottom.

I have been trying these suggestions (about placing down the clay and how to cone better to avoid the bubbles), to no avail.

I think I am doing something when I am making a hole in the center (after centering), but I'm not sure what.

I have asked some friends but nobody could really help, and I'm no longer in a community studio!

So if any of you guys have ideas about how the same problem might be caused by something done while making a hole or flattening the bottom, I'd love to hear!

[Babs]

After you wedge upur clay and either make it into balls or shape for throwing off the hump, try rolling the ball on wheel so the bottom cones a bit then press it down .

Try throwing and opening a piece without the coning process to isolate whether that process is the culprit.

Edited January 26, 2023 by Babs

[Bill Kielb]

On 8/7/2022 at 4:43 PM, Finn Ewins said:

I use the same technique but for some reason on my new wheel the base of my clay is always off-center / feels like there is an air bubble trapped. 

@Tova Cooper Just a couple thoughts -
I suggest to make sure and cut it cleanly off the wheel several times to see if in fact there is an air bubble. You may need time to perfect your centering in the new environment and it simply may not be trapped air.

Additionally rounding your clay into a ball ensures that the center will touch down on the wheel head and as you push down, air will be expelled as it seats on the wheel -:thrown or placed and pressed.

Edited January 25, 2023 by Bill Kielb

[Babs]

Is your wheelhead sitting level in its new position?