Cracks where handles attach

[GreyBird]

Hi all,

I am not used to working with porcelain. I usually use stoneware and had never had this happen with my stoneware cups but the porcelain might dry a bit quicker. I threw some cups (10 cups!) and so after throwing the cups I then went down in the morning to add foots and handles. I did notice the tops of the cups were dryer than I would have liked... not bone dry but still. Then later that night I checked them and noticed cracks forming around all the areas where the handles attached so I started frantically painting over them with porcelain slip in an attempt to "erase" the cracks. I had them all covered up. This morning I checked and the cracks have re appeared albeit much somewhat smaller. Can I just keep painting them over with slip until the cracks no longer appear or are the cups doomed? (See attached)

-Mary

 

 

[Callie Beller Diesel]

The top picture looks like you used too much water (or your slip was too fluid) and not enough wiggling to attach the handle in the first place. I've found that some porcelains don't like to have a lot of differences in the moisture level between parts that are to be attached to each other, and that covering pieces for an hour or two to allow attached parts to get used to each other before you allow them to dry. 

To fix the crack in the second picture, I'd just take a pointy wooden tool of some kind, and just compress the crack. No need to add more slip, and in fact if you do, you'll just  be fussing with the pieces more than necessary.

If you run into this situation again, porcelain can sometimes be gently re-wetted by spraying pieces down and covering tightly with plastic for about 10-20 minutes.  Repeat this process at intervals until your mugs are back to a workable state. 

[neilestrick]

Porcelain is finicky. It shrinks a lot more than stoneware, so if there's a big difference in the moisture levels of the handle and the pot, you'll get cracking as the handle dries. So attach the handles as wet as you can, or shape the handle and let it set up as much as possible before attaching it. You can even pull and shape the handle on a bisqued mug, then take it off as it sets up, let it set up till it's almost stiff, then attach it to the real mug. Also, the less you smooth the handle onto the pot, the less cracking you'll get. You can also just attach the top  of the handle, and let it set up until it's just barely still flexible before attaching the bottom. Lots of options, you just have to figure out which works for you. Porcelain handles will never be as easy as stoneware, though.