A Lesson (Hopefully) Learned


 Well, this is a bummer.  This photo was posted a few days ago on Facebook.  


I knew going into the firing that the plate on the left had a crack, around the ridge but the other plate was completely ok going into the kiln.  


After the initial sting of finding them cracked,  I was off to find a reason why this happened and how to keep it from happening again.  


What appears to have happened to the first piece was either there was a bit of water left on the piece that settled into the spot where the lip rises and that moisture created a spot of unevenness in the drying process.  


For the other piece, that crack appears to have come from uneven heating in the firing.  I had the plates stacked, which I've done many times stacking pieces: tiles, bowls, smaller pieces inside of others, but I think somehow there was an uneven heating causing this crack.  


I completed this firing in the test kiln which is a small kiln that has an interior of about 12" across and deep, and about 7" tall.  This small space may have contributed to the unevenness as if I did not make the firing schedule long enough.  

Needless to say, my plan is to now use the large kiln with  a slow bisque to hopefully keep this from happening again.  The challenge is that I need to fill the kiln, but I won't know how pieces will look until after the clay is fired, and can't be recycled and used again! 


The two cracked pieces, I debated trying to fix, but I know I would spend more time trying to fix them compared with just making two more plates - so I will use these two for some tests using stains with the glaze.  Since I'm not comfortable safety-wise regarding the food safety issues with using more period based glazes, and these have obvious cracks, they will clearly not be used for actual food.  


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