Jump to content
Sign in to follow this  
dodid

Help: Air Bubbles!

Recommended Posts

In advance I apologize for my 'potty' question as most of you are professionals. I have been trying my hands at throwing for one year. Finally I get the wedging and even the centering :-). But as every time I tackle one problem a new one appears, my newest challenge is air trapped between the clay and the wheel. I form the clay into a ball and throw it down on the wheel, tap 5-10 times and then I start centering. When I open I feel the air bubbles unter the bottom of the clay or toward the rim. What am I doing wrong? I really appreciate any help you guys can give me.

Greetings.

D.

 

Share this post


Link to post
Share on other sites

probably happening when coning up, you may be pulling the cone a little to hard and pulling the base loose and letting air under.. when you drive the clay down, you trapped the air under the base...

 

#2 - if you are pushing the cone forward while in the up position it can pull the base away as stated above... drive down,trap air.. keep a eye on your base while coning up/down if you see a crack, there is the problem

 

 

it is still important to ball your clay and set it as close to center as you can, then hit it firmly 2 or 3 times with your palm.. sometimes throwing it can trap air..

Share this post


Link to post
Share on other sites

Are you sure you're not introducing them when wedging and they only become noticeable when throwing?  If I understand you correctly you're finding bubbles at the rim as well?  That would point, maybe, to air bubbles being introduced during wedging.

 

If you're slamming the clay onto the wheel head and you're firmly patting it onto the wheel head, I can't imagine that being the cause.

Share this post


Link to post
Share on other sites

I agree with Tyler.  I find it odd, that you'd be able to pull a bubble from the bottom to the top, especially one, that was created between the wheel head and clay.

 

I've never had any issue, with air bubbles, simply by slamming the clay on the wheel head.  The biggest issue, and one that my students seem to have, is that they don't round/ smooth their clay ball/ cone, and have creases that remain.  

Share this post


Link to post
Share on other sites

read his question again.  i have had this happen in the past and it is not what you are thinking of as a "bubble", a smallish thing that travels up as the clay is thinned and pulled.  this is a larger problem that is at the bottom of the clay between the clay and the wheelhead.  it happens when the bottom of the clay ball is not allowed to flatten out onto the wheel but is squeezed from the sides so quickly that air is trapped between the hand and the clay.  i have thrown things and found when the bottom is exposed that there is a hollow left from that trapped air.  it is a hard habit to break.

Share this post


Link to post
Share on other sites

Oldlady, when the original poster said "rim", I was thinking ofmthe top. I did know what they meant by an air bubble getting trapped there. I've runninto it myself, and seen many of my students do the same. I just thought they meant, that they were pulling that bubble all the way to the top.

 

Bruce's method is a great solution.

Share this post


Link to post
Share on other sites

Hello all,

thank you so much for all the comments. After reading each one I have the feeling that it might be the problem that Crusty and Oldlady discribe. That I am forcing the clay too much while coning up. Tyler, I explained myself not well enough: When I am talking about the rim, I didn't mean after I pulled the clay up. I meant the bottom outer corner of the opened clay ball. And it is like Oldlady says a big bump, not just a little air bubble. When I think back it started when I saw a video on youtube that pointed to using the pressure creating by my fingers rather than the palm of my right hand when centering. And suddenly it was much easier to bring the clay up but looking back I think that is when the air bump problem started. I will try today with less force and will let you know. Have a nice day you all and greetings from switzerland.

Dorothe

Share this post


Link to post
Share on other sites

I second Bruce. Best to pat the clay, after wedging, into a pear shape (or cone). I never slam the clay onto the wheelhead but only put it there (a bit brisk). I try to put it as much into the center as I can, start the wheel turning slow slow and pat it more into the center of the wheel. Then I stop the wheel and push, with my thumb, the part of clay that's connecting with the wheelhead carefully down all around.

 

Dorothe, I'am from Switzerland too. Welcome to the forum. Could you please tell us a bit more about yourself, what kind of work you are doing, maybe show a few pictures of your work? And please fill in your profile. We are all friends here and try to help and advise each other. We can do that better when we know who you are, where you come from etc. Thank you! Keep posting.

 

Evelyne

Share this post


Link to post
Share on other sites

Dorothe, just for the info to pass on to the management of this website, when you signed on originally, did you find it easy or hard to enter the information about yourself?  is that why you did not include a location or did you want to protect your privacy?

 

i have been telling the management about what i see as a problem but have had no corroborating information from anyone else.

 

i had a friend, a former microsoft troubleshooter, send an email about the difficulties on the website re posting pictures and as of yesterday, the email i sent has never been read.

Share this post


Link to post
Share on other sites

Just briefly, have to go to bed. I am cured ;-). I focused on not forcing the clay too quickly up and giving it time to settle onto the wheel and the big airbumps did not reappear. Thanks so much to everybody for the helpful input. As for the feedback on the website and info about myself, I will write more tomorrow. Too tired now. bye.

Share this post


Link to post
Share on other sites

dodid, glad your doing better.. Bye the way a lot of folks call that a- Potters Lump-  I had a go with it when I tried this new clay body, its a firm body, as I was working with a soft body with no problem..

 

you say up by the rim ,,,that means it might be made by your index finger and thumb area on either hand,, just keep a eye out for it.. sometimes it can come back...

 

keep throwing and good luck to ya..

Share this post


Link to post
Share on other sites

When you have your ball of clay in your hand, give the bottom a quick "roll" around on the bat before you throw it down. It will smooth out the bottom, trapping no air on the bottom rim.

 

Another tip is to align your ball of clay on the wheel so that its spins in the same direction as you wedged it. You already have the molecules aligned from wedging into a spiral so keeping them facing the same direction you will make stronger pot with less issues later.

Share this post


Link to post
Share on other sites

Hey,

I start every piece by wedging the clay.  I wedge the clay to see if it is too stiff to wedge.  If you can't wedge it,

you probably can't throw it.  Clay that is too stiff is sliced in 1/4 inch sections with water added between

each slice.  It is usually turned on its side and sliced/watered again.

When its wet enough, I start wedging.  After so many times, I slice the clay into and examine the cut surface.

If a large air pocket isn't apparent, I slam my hand on each section.  Any air pockets near the cut

surface will pop out.  The two sections are put back together, and wedging starts again.  The idea is

to make creases in the clay.  As the clay rotates around any bubbles will break in the creases.  When

bubbles stop showing up, its time to throw.  When I'm making 1 1/2 pound vessels, I'll wedge 6 lbs.

and cut it into fourths.

      I go to a notebook and look up examples that I make.  I use the picture in the notebook as a

blueprint to make the vessel.  When trimming starts, the notebook comes back out to finish it. 

I know what glaze that vessel will be, before it is thrown.

There are not many "surprises" while making my stuff.

      As a beginner, make lots of pottery.  Cut your losses early, if a vessel begins to fail on the wheel.

Hope this helps.

Alabama

Share this post


Link to post
Share on other sites

I just put my pug mill into operation. It is not de-airing, so I expected to find bubbles in the pugged clay. They are not there when I slice the pug multiple times. But sometimes, after I open on the wheel, I find one or two bubbles, usually after I attempt to make the bottom of what I am throwing, flat. Bubble  or bubbles appear in the very low part of the sides of my bowls. This is consistent with some of the posts I've just read here. I have been cutting clay from the mill and then slamming it down on the wheel, thus trapping air under the clay(maybe). It centers and works beautifully, except for those occasional bubbles. Thanks for all the great information on this! 

 

                                                       john a.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.