tkw954

I should add that I'm slip casting, so I'd be willing to make additives to the clay if it would help preserve the color.

I'm working with a wild clay that fires to a really nice rich, dark brown color when fired to cone 6 electric. It's quite vitrified at this point and will slump so I've been making some marble pieces with a commercial clay that works out nicely. However, when I try to apply a cone 6 clear glaze ("Mastering Cone 6 Glazes" glossy clear liner") the dark browns turn to light tan. Is it possible to formulate a clear glaze that won't wash out the clay's deep color? I've attached a picture with the unglazed marble on the left and the glazed version on the right. My marbling process changed a bit so only look at the color of the dark parts, not the fineness of the marble. You can also see the effect on the rim of the left cup as I applied a liner glaze with a rim around the outside of the lip.

I'm considering a brick rebuild on a Skutt 181 (8 sided) kiln. It has some worn bricks at the top level that leave a gap under the lid and struggles to reach cone 6. Also a number of the element bricks have broken grooves so the elements sag. I figure I'd need to replace about half the bricks and was wondering if it would be reasonable to take all the good used 2.5" bricks and put them in the upper half's metal band and then buy new 3" bricks and use them for the separate bottom half band. I realize this will decrease the inside dimension of the bottom half, but I have shelves that will fit. Is there any reason why I can't have different bricks on the top and bottom?