Test Glaze Firing

So I fired my test glaze pieces a couple of days ago.  I had numbered each piece on the bottom when I threw them so that I could track what I did to each one in terms of glaze thickness and placement on upper or lower shelves.  I wanted to test two different glazes:  the first, red chun, has always been a difficult glaze but when it works out well, it’s really beautiful and probably my favorite all round glaze.  However, instead of coming out red my pieces have been coming out rather gray and I couldn’t tell whether it was because the glaze was too thick, too thin, the kiln was too hot or too cold.  So I put one with thick glaze and one with thin glaze on each of the 3 shelves.  There’s about a whole cone’s difference in temperature between the top shelf in the kiln and the lower as you can see from the photo below.  

These are 5, 6, and 7 cone packs.  I'm trying to fire to cone 5.  I had to put a cone 7 in the kiln sitter and I think it still turned off the kiln a little too early. The single ones are cone 5 which I put right in the peep hole to be able to see it best while firing.  You can see that the cone 5 and cone 6 bent fairly nicely on the top shelf; just the cone 5 bent on the middle shelf; and the cone 5 on the bottom shelf only bent slightly.  

So . .

#1           red chun – thick glaze – bottom (cooler) shelf 

#3           red chun – thick glaze – top shelf

#4           red chun – thick glaze – middle shelf

#2           red chun – thin glaze – bottom shelf

#5           red chun – thin glaze – middle shelf

#7           red chun – thin glaze – top shelf

Starting from the left front they are numbered 1, 2, 4, and 3, 5 7 coming down from the back on the right.  The larger piece in the back is a red chun when behaving well - the color that I'm going for.  

There really seems to be almost no difference overall.  Each of them are fairly gray but each has a section that's got a little red tinge to it.  So I can't say that the test firing taught me anything.  Bummer.  It's still just red chun behaving badly.  Maybe it's just a bad batch.  I buy my glazes all mixed.  The glazes I'm accustomed to using are ones that my pottery teacher, Malley, mixed herself.  

The other glaze I wanted to test is the royal blue which has always been a really solid glaze, didn’t run much and showed off embellishments fairly well.  However, mine had been blistering and running and again, I didn’t know why. I think I did learn something from the royal blue test glazes.

It seems the thinner glaze on the cooler bottom shelf works best for the royal blue, though they all seem to have some blisters.  I really need to get this one right because I'm going to use it for a nice covered casserole dish and don't want to mess it up.