Handles snapping in two.

[Rick Wise]

Lately, my handles have been cracking like shown here -- probably 20 to 30% of them.  It occurs in the same spot at the bend of the curve and  after they have been turned and are going to  bone dry.

(If they make bone dry OK they never crack later.) 

Not sure why since the clay and the techniques are all my usual.

At any rate, it seems to me that there should be something I could do to help prevent this but I cant figure out exactly what it happening.  All ideas welcomed.

[liambesaw]

Looks like a memory issue to me, are you keeping them moist while forming them?  They look slabbed so I'm thinking they may have stiffened up too much before you shaped them into an ear.

[Pres]

Rick, don't know where your are right now, but depending on your location you could be having humidity/dryness issues. I have found that slab and coil handles are more susceptible to the humidity levels and that is one of the reasons I would always pull handles when working in the summer, and now with my electric putty gun extruder. You may try a few tricks with your slab handles, especially with these finely decorated handles. Try making the handle a little thicker. decorate, and then cut, throw slap the handle onto a board so that it stretches slightly lengthwise. This will align particles and compress along the handle length. When you have the handle joined try a wet finger on the inside of the handle rubbing in the length of the handle to shape and stretch a little more. Then turn the mug upside down to let dry covered with plastic. You may want to consider a little coil filling along the joins at top and bottom to give those areas a more finished look. This always works nicely for a smoother glaze finish also.

If you wish to know more about a cheap Ryobi putty gun extruder check out my blog site, or run a search on the Studio Operations grouping.

 

best,

Pres

[Mark C.]

When our handles start cracking (about the same spot). They are extruded-it usually means the clay was a bit to dry (wetter handle clay needed)

I cover all handles one night with light plastic to equalize .

[neilestrick]

You're attaching them too wet. Make the handle, and immediately lay it out in the shape you need. Let it set up until it's just barely still flexible, then attach it to the pot when the pot is as wet as possible.

[Babs]

I had this same problem and posted it on these forums but can't remember what heading I gave it.

It came about when I finished the handle by flattening and impressing texture onit by rolling on the type of board you have on your top. It seemed to suck more moisture out of the handle andcso the cracking. Mine wasn't obvious untill after glaze firing!!!!

I am with Mark on this one. Clay/handle ended up too dry before shaping thus cracking. 

Someone smart may be able to find my post. Think I lost about 30 odd mugs out of forty.

https://community.ceramicartsdaily.org/topic/20190-interesting-results/

Found it

[oldlady]

rick, is that cement board under the mug in the photo?  are you rolling the handles on that absorbent surface and it is getting too dry?   just wondering.

[Bill Kielb]

I like all the above but would add  as the handle shape becomes more linear (less curve) when the mug shrinks and the handle has to follow the mug it may be difficult for this clay to keep up. All that stress has to go somewhere and if the handle drying rate doesn't match the mug within  reason, snappo! An extreme example of this would be a handle shaped like the number 7 with a very hard change of direction, say 120 degrees or so. Tough for that joint to take all the bending. Often folks will sweep their handles up then downward just so there is more of a gentle curve to tolerate the bending when drying rates differ. This way, their handles are not so picky with respect to drying. Your handle appears pretty thick with respect to how you throw your mug, nice handle but if this becomes too tedious to keep at the same drying speed then maybe explore a little shape redesign to give it more flexibility while drying.

[Babs]

I solved my prpb by using slightle damper clay and working on cloth covered board instead of the cement board to flatten and impress.

Place on wooden board and cover with plastic till attached

[Chilly]

On 7/23/2020 at 2:56 PM, Bill Kielb said:

Your handle appears pretty thick with respect to how you throw your mug

As Bill says, nice shape, but looks much thicker than the mug.

[Sorcery]

Why is there discoloration at the join?

What is the...texture...of the texture?

If the texture is a Matt, or bendable and continuous, you can fold it and use a finger to rib your handle into shape, impressing the texture and shaping at the same time.

Sorce