Wednesday, December 17, 2008

Why So Many Buts ?

Silver Sheen Platter
15" x 10" x 1.5"

This is one the platters I made last Spring. I glazed it with an orange shino. When it came out of the glaze firing it was milky and beige and the glaze wasn't mature at all. Unfortunately I don't have a photograph of what the platter looked like after the first firing. I realize I need to keep my camera with me at all times to document the results of each firing.

I kept the platter for further experimentation and about a month ago I applied wax resist and brushed on temoku over the whole platter. This is the result. The color combination and textures are so unusual and appealing to me. Orange and a metallic silvery sheen. I really like this effect.

But, why are there so many buts? For some reason or another it looks like there are impurities in the clay coming through in several places from underneath the glaze. These bumps were not in the platter with the first firing. Does anyone know what these bumps could be? Could it be the shino fighting with the temoku? I plan on trying this combination again and am hoping I can get similar textures and colors but without the bumps. If the bumps were on a vase, I guess they would be OK, but on a platter, not so good.


  1. That is a handsome finish on the platter. From the photos, I am having a hard time seeing what you mean about the bumps? All looks well to me. The only thing that I think you may been referring to is the orange peel texture, which some think is a desired thing.

  2. Oh, just looked at the pics again and I see what you are talking about. Almost like bubbles or blisters. I have had that happen with some shino glazes before, but I am not sure why. I have one small vase that was completely blistered all over, most of them had burst as well. It makes a good pencil cup, but cannot really be handled much.

  3. I had this happen on a couple of pieces in my last firing. They aren't bumps in the glaze on mine, but bulges in the clay (or they appear that way, as do your bumps to me anyway). I assumed that it was trapped air, but logic told me that it would have happened in bisque as well, not just the glaze firing. Maybe my assumption of a clay issue instead of glaze one is wrong, but it only happened on pieces made from reclaimed clay, not fresh out of the bag. Maybe in my case it was impurities in the clay? I just don't know--I'll stop rambling now.

    So, in other words, I am no help at all and I'm quite stumped as well :) Hope someone has a good answer for you.

  4. it IS a nicely finished item, now lets talk about gophers again

  5. I can't tell from the photos if the bumps appear to be in the glaze or in the clay. If they are in the clay, a relevant question would be, how early did you go into reduction, and might this platter have been a in a cool spot in the kiln (cool at the point of body reduction, not at the end of the firing)? If in the glaze...not sure. Shino sinters earlier than most other glazes, which is why it sometimes causes problems applied over other glazes, but under? On a refire?
    Not much help here, I'm afraid.

  6. Thanks Jerry, yes at first glance it's ok, but then you can see the bumps about 5 or 6 in the platter, most of them on the flat part near the edge. I just lunged at the platter when it came out of the kiln and then I saw the bumps, what a disappointment.

    Like bubbles as you say, and they do look like they are coming from the clay.

    Hi Ben, thanks I am kind of stumpted too. I made this platter last Spring from fresh Rod's Mix stoneware, then it was bisqued, then it sat outside the classroom during the summer (the painters moved the wares outside to paint inside). Then in the early fall, I glaze fired it with the shino, but the glaze firing didn't get up to even Cone 9 so the shino didn't mature and was just creamy beige and kind of streaky. So I kept the platter since other than the bland color it was nice and I thought about reglazing it. That's when I decided to try the wax resist and temoku over the top and do another glaze firing. And this is what I got.

    Hi Gary, thanks, I think the platter color coordinates with the fur of gophers, don't you? he he.

    Hi Potterchik, nice to see you here. Thanks for your suggestions. My platter was on the bottom shelf of an updraft kiln which is hotter, but the second glaze firing was faster and early reduction, so that might have something to do with it.

    I am definitely going to try this glaze combination again. I plan to overlap the glazes all in the same glaze firing for one test. I'll also try the two glaze firings in another test. Hoping to get the shimmery silver and orange combination again, which I just love - but without the bumps. I hope I can figure this one out so I can recreate it. I will also try this glaze combo on a more upright surfact to see what happens - less surface on the kiln shelf - this platter does not have a foot.

    I have another studio where I bring some of my Cone 10 work to fire - and I would like to see what they can do with my testing on this combination. I hope to have more results about this combination next Spring after some testing.


I love suggestions, questions, critiques, thanks for your comment