Avoiding cracks at handle joins ?

[tomhumf]

I get these little cracks where I've added a filler bit of clay at the base of handles. It happens quite a lot. The jugs had been dried, then put in an oven on low for a while to make sure, then I've gone around the join with slip a couple of times, drying in between.

They don't matter so much if glazed but I prefer to have these parts unglazed and it looks rubbish to have cracks showing.

Any ideas how to stop this, also any ways to salvage ones that have got cracks already? Thanks. 

[Denice]

Do you put any plastic wrap over the end of the handles while they are setting up?   The jar looks like it may have been pretty dry,  the soft clay you put them together with is shrinking causing a crack.   The potters I have watched that are good at handles work with handles and jars that are pretty wet,  they cut the handle angle they need and score the jar.  They put a little sloppy clay on the score area and gently wiggle the handle into place.  Next they connect the handle at the bottom and straighten it.  The connecting edges are smooth together almost burnished,  on a long thin handle I would wrap it in plastic so it wouldn't dry faster than the jar.   Denice

[JohnnyK]

If the jugs haven't been bisque fired, you might be able to sand or file the joints to remove the offending slip. If bisqued, the option might be a diamond bit to grind the joints...

[Mark C.]

Before bisquing rub these out with wooden stick. they will go away

Cover mugs right after handling for a night and this e many never show up to begin with

[oldlady]

agree with all above.   just want to say that the handle line is excellent, not too far out or too close to the body.

[Bam2015]

1 hour ago, oldlady said:

agree with all above.   just want to say that the handle line is excellent, not too far out or too close to the body.

Agree, nice handle!

[Bill Kielb]

Agree with all the above but would add in the design of your handle judicious use of curves to allow the handle to bend while shrinking can help a whole bunch as most often the cup and handle will not shrink proportionately in height. Having enough radius in a handle to reduce the axial strain can help a great deal and is often discovered by trial. Final thought, compressed clay is dense clay is much stronger than non compressed. Think steamroller type road compression and realize that to compress things one needs to push the clay into compression. Wet clay starts out less dense, so compressing these joints at different states of dryness is a thing that can be a helpful practice.

The mug below because it is clear glazed and porcelain, requires perfect finished joints otherwise a hairline visible crack makes it a throw away. The handle is very specific and requires a good top radius, slight looseness in the bottom chord (reducing drying tension) and good joinery followed by addition of coils at attachment time compressed well with a tool and final shaped after thorough compression. Floating joints are also a visual option and require less work as the crack is intentional, uniform and filled with glaze.

 

[Mark C.]

We handle hundreds of mugs every month. The handles are extruded but that will not matter. Spray down the mug if its dry to get it the same as the handle. Score and slip the attachement points -force the handle on and mash it into mug. If you need to sponge that transition -we just use our fingers. Cover the mugs for a night so they equalize (this is a very important step) we do this will porcelain mugs which like to crack more than stoneaware.If there are any cracks I stick them smooth when dry or Simi dry. They go away

[Babs]

Dont use slip, use 50:50 water and vinegar, or magic water to fix handles.i use a toothbrush, roughen up area of pot where attachment will be, and handle ends . Wriggle to get handle to adhere, smooth out with sponge dampened in mixture above. Compress with tool. Dry under plastic 1st night (in summer esp.)

[Mark C.]

The slip I use is off my hands collected when throwing and use a brush to apply. It thick and add vinegar to it to thin