Suggestions for mugs and cups going "out of round" when drying?

[Rick Wise]

On a seemingly random basis, I have cups and mugs whose rims warp while drying from wet to leather hard.  The handles have not been attached so that is not the culprit.  I try to make sure that drying is "even" and not drafty.   If I notice at just the right time I can sometimes "re-round" them but often they are too dry and will crack if I attempt to alter them back into shape.

I would love to hear anyone's thoughts on what causes this, how to avoid, or how to correct when it does happen.

(I've tried letting them dry with a dixie cup inserted into them flush to the rim.  But then the cup shrinks onto the dixie cup and it difficult to remove)

[Bill Kielb]

I can only say that for my very round stuff that needs to stay round when I throw, it needs to be finished round and uniform. If at any point I bump it or it gets out of round then at least one axis of the cup has stretched a little and there may be nothing I can do to keep it as round as practical. So for me throw it very round, rib inside and out compress the rim and remove it to a ware board  (very round) with an ordinary paper towel under the ware. I don’t use batts a bunch for this so often I will lightly torch dry it for a few seconds so I can remove it from the wheel without changing its round shape. (Sounds weird, but works for me)

Why the towel? The ware will not stick and pull itself out of round and it’s an easy way to get the bottom to dry nearly the same speed as everywhere else. Once that is done I just set it in a draft free location and let it dry fairly rapidly.

Not sure that helps but it seems to keep my stuff pretty straight (Round) without a bunch of fuss.

[Babs]

I saw a video maybe Callie or Min posted that had a glimpse of an insert that held the mug/ cup in the round  after applying a handle.

Naybe that would help

[Mark C.]

how are they drying? in a no wind no sun area? outside in sun? no air movement arount them? some details may help

[Bam2015]

Are they wheel thrown or hand built with a seam? 

 

[neilestrick]

Drying too quickly is always the culprit with my mugs. There are a lot of possible causes, though, and every clay body behaves differently.  It could be the evenness of the piece, how you remove it from the wheel, even how you throw it. Next time you get a warped one do a close examination and see if you can figure out what makes it different than the others.

[Chilly]

You're "dixie cup" needs to be more like a funnel.

[GEP]

If it’s happening randomly, the next time you get one that warps, cut (or break) it in half both vertically and horizontally, and look for uneven thickness in the walls. 

[Mark C.]

I use plaster bats so the bottom dries without touching the mugs.(no cutting with wire) Porcelain can warp in the wind or sun but usually its fine if the lips are thick enough

[Pres]

Let the rims stiffen to cheese hard, then flip to dry the bottoms. I have found that in most cases if I have a warped area, it is usually because the rim was pulled too thin. I always chamois the rim (actually use my first and second finger web) to thicken/compress the rim. The cone idea works for some, but the compressed rim usually does the trick.

 

best.

Pres

[elaine clapper]

Drying upside down as soon as the rim is strong enough for support seems to work best for me.

[Rick Wise]

On 5/29/2021 at 2:25 PM, Pres said:

Let the rims stiffen to cheese hard, then flip to dry the bottoms. I have found that in most cases if I have a warped area, it is usually because the rim was pulled too thin. I always chamois the rim (actually use my first and second finger web) to thicken/compress the rim. The cone idea works for some, but the compressed rim usually does the trick.

 

best.

Pres

I have a good feeling about this suggestion!  Gonna turn over a new leaf and make my rims thicker.  Thanks

[Pres]

Old prof used to talk about the rim of a mug "kissing the lip" , in my experience too thin, and they are sharp and poor feeling, too thick and they tend to dribble and feel uncomfortable.

 

best,

Pres

[Rick Wise]

Mine end up too thin I think because of my misguided effort to get all the "height" I can from the given amount of clay.  Leaving them thicker should not be a problem since I end up trimming them extensively anyway.

[Bill Kielb]

1 hour ago, Rick Wise said:

Mine end up too thin I think because of my misguided effort to get all the "height" I can from the given amount of clay. 

As you pull more and more, you become better at making everything pretty much the same thickness as well as less trimming  so that definitely will help. Kind of outdated, but might give you some ideas https://youtu.be/49FBMLh3bKU

You can always compress then chamfer the very top.