Different clay thickness in same firing

Fill up the kiln as much as you can. I would not place all your real thick pieces together, although some may think differently. Although it is not necessary on a bisque firing, I think I would add a 10-15 minute soak/hold at the end of the firing. Steve in Tampa

In a student studio you have a huge variance in the pots you fire. When bisque firing I make sure that when stacking that I don't put a heavier piece inside a thinner piece. If I put a piece in or on a piece and that piece has any weight, I am careful that the weight is carried on the foot other piece (so foot is on top of foot - I would never put a piece of any weight on a thin wall). We always soak the kiln overnight on the bisque firing to make sure that heavy pieces really are completely dry and that the heavy pieces have time for the gas in the clay to escape slowly. Given that some students pieces are at places over an inch thich while other parts or other pots are less than 1/4 inch I could not imagine you having a problem as long as you fire at that rate that you would for your heaviest pieces. DKat

As long as the work is completely dry and you ramp up the kiln to 600C very slowly, like at least 100C an hour and no faster it should (no guarantee's) be fine. Air bubbles and moisture are your worst enemy, next to firing too fast. A

I fire different thicknesses all the time. I find that a really long first stage with the lid cracked and then checkng the second stage to make sure there is no moisture works . I often fire leather hard pieces this way and have not had a disaster for years. Slow firing forgives air bubbles,moisture uneven thickness even huge thick solid works NJ

I think that only real issue with thicker pieces is making sure that they are totally dry, - they can take unbelievably long time, as I have discovered when I 've lost a kiln load few years back due to impatience. :o)

Andrea

Thanks all of you for your responces to my question and the additional information you have given. I have the answer to my question and feel a lot better about my next firing. Much appreciation again, Crystal