Saturday, 22 June 2013

Some pots from the latest firing

I never know quite what to expect when I open my electric kiln. Even the relatively consistent glazes come out slightly different each time. Despite the disappointment of some pots not turning out as I hoped, I always enjoy the surprises, and the fact that I learn something new each time the kiln is fired. What were the surprises this time? First of all an ash glaze with a 6% addition of rutile, which I hoped would turn a shade of yellow, came out a very subtle beigey off-white with some greyish tones where thinner:

Vase, 2 inches tall
This might be made more interesting with some orange or yellow stain added.

Then there was the black slip glaze, made with clay dug straight from the fens of Cambridgeshire. I learned that this glaze is more matte and silvery grey when thin and blacker and shinier when thick. Also, if there are cracks in the glaze when it dries, it's going to crawl..and where really thick it's going to spit glaze onto the kiln shelf! I was really lucky, as one vase did spit glaze, but every drop landed on the bits of broken kiln shelf I used to stand the pots on. Phew. I don't mind the crawling so much, but this glaze leaves behind some black residue on the bare clay (probably from the small amount of cobalt oxide) which is rather unsightly. Here is an egg cup which crawled a little:

Some of the other pieces with the fen slip glaze:

Espresso cup ( Nami-jiro glaze to interior )

Vase, 4 ins tall

Miniature vase, 1.5 ins tall
Beaker, 4 ins tall  (ochre ash glaze inside)

Vase, 3 ins tall
I had mixed together the translucent ki-seto glaze and the opaque nami-jiro, 50/50 to see how it would look. The result is more transparent than opaque, and tinged with green from the wood ash:

egg cup with copper oxide splashes
Shot cup, 2 ins tall
I also made up a Ki-seto glaze with washed ash and around 3.5% yellow iron oxide. Not sure what happened here; the glaze application is extremely thin in places and the glaze has a strong green colour:

Sake cup, 2.5 inches tall
Quite surprised if all the green is coming from the wood ash as this is mainly oak which usually gives more yellow-brown tones in oxidation, however the yellow iron content may be too high also. I'm wondering if a yellow tint would be easier to obtain with less wood ash, perhaps by partly replacing it with whiting. A paler clay body with little or no iron content may help too.

Very pleased with this little sake cup which was glazed with the Leach Old Seto Yellow. I think the wood ash content here was around 35% and it works nicely over the groggy clay..I love the way some of the alkalis in the wood ash have vapourised and turned the foot a nice toasty brown, not something one achieves too often in an electric kiln:

Sake cup, 2 ins tall
Next, a few pieces glazed with the ochre ash glaze. This glaze never ceases to amaze me with its variability, depending on how thick it's applied, the type of clay body, how quickly the pot was dipped after stirring the glaze..etc.

Vase, 4 ins tall

Espresso cup, 2.5 ins tall

Espresso cup, 2.5 ins tall
The colours can range from black to rust-red, to orange to yellow and grey-green.

A vase with my new Oribe glaze:

Vase, 4 ins tall.
And finally, the one and only saggar-fired piece:

Hmmm, I'm liking the cracked texture alot, but colour-wise the result was rather bland .. it's a pity the whole pot didn't have the same finish as this small patch of the surface which turned a wonderful iridescent gold-rust colour. Not entirely sure what caused this as I put a mix of things in there (charcoal, wet banana skin and fresh cherry pips!) .. perhaps it was the cherry pips. I've put elderberries in raw in the past and the juice from those added a silvery iridescence to the pots's something I've been meaning to try again for some time. I'll have to wait for the elderberry season  in September.

Thanks for reading :)


  1. Mark these glaze experiments are turning out some really sophisticated finishes. Keep up the great work.

    1. Hi Sam, thanks so much for the encouraging words. Hope all is well with you.

  2. How interesting! I love the first glaze. That's a beauty! You made me feel to do more glaze experiments! Thanks for sharing! : )

    1. Thank you, Midori .. I wasn't sure about that glaze at first, but it's growing on me slowly. :)

  3. My word you've really out done yourself with this firing. Love the black, either matt or shiny. The black is so elegant on the forms. The oribe turned out luscious. I especially like the sake and espresso cups.

    1. Thanks so much, Linda, for the kind comments :)