Friday, September 16, 2016

not as expected

I like a lot of different glazes, and seem be particularly drawn to rich, dark glazes.  However, my usual tenmoku glaze is temperamental.  The plum, almost black, glaze that I love may be driven to extinction by poor record keeping.  Note to self:  Do not assume you will remember which Albany Slip clay substitute you used.  Several mugs have been sitting around for some time waiting to be glazed with plum glaze once I figure out the Albany Slip thing.  I have a couple of containers of Albany Slip that I made using different recipes.  I seem to remember combining these to get the right look for this glaze.  Or did I use some of the commercially made stuff?  There are a lot of recipes for Albany Slip- apparently no one has found the secret to duplicating the real thing since mining ceased.
I have temporarily given up on the plum and decided to try a new tenmoku.  Normally I make 200 gram tests, but was feeling trusting and made 500 grams so I could skip the test tile and go directly to glazing a mug or two. This meant having just enough to dip the bottom half, then turning to dip the top half.  I did place mugs on some reject wall tiles saved for this purpose in case something really bad happened (like glaze melting off the mug and later cooling into a pool of obsidian on the kiln shelf).  I expected a standard translucent brown, but got this great deep rust red.  Okie dokie.  Tested a few brushstrokes of other glazes underneath the tenmoku and even took notes- and put notes in a sandwich bag with the glaze recipe taped to the lid of the glaze bucket. I'm hoping this proves to be a reliable glaze.  Recipe follows at bottom of page.
We should all have a blue pumpkin.  Just made one of these because I thought it might be too weird but I kind of like it.  I veered away from my usual pumpkins this year and went with a satin matte glaze instead of shiny.  Let's try a spotted pumpkin, too.  Speckled clay used here.
There is an iron oxide engobe on some stems, which is dark and metallic. For a couple of the pumpkins I brushed the iron oxide engobe on much lighter and went over it with a rutile engobe resulting in a less shiny golden brown.  Then I remembered that I have an iron ox./rutile/frit wash which I dabbed here and there on the pumpkins to get some interesting spots on the ones with non-speckled clay so they wouldn't be jealous of their freckled pumpkin siblings.  This wash may have worked well on the stems, but I'm fresh out of pumpkins, so no more experimenting for now.

Tenmoku   cone 6 oxidation, source unknown (yeah, I didn't write it down)
slow cool:  125 degrees/hr. from 1900 F. to 1400 F.

silica flint        25.
EPK                16.7
Neph. Sy.        16.7
G.B.                  8.3
Dolomite          8.3
Talc                  8.3
bone ash           6.7
Red iron ox.    10.    used Spanish Red


  1. Hi Melissa,
    those are beautiful pumpkins, including the blue one! I love the twisty stems that look like they are still alive.
    Regarding the Tenmoku recipe, isn't glazing fun!! Your recipe looks just like what I would expect for an iron red, I can't help but wonder if the recipe has been mislabelled? I think that the bone ash is what is chiefly responsible for giving you red from iron, but you also have a lot of magnesium in the glaze as well which will be promoting the growth of little crystals in the glaze, which could prevent it from being a dark, translucent tenmoku, but may assist the iron red. Having said that, it certainly looks like it could be a very nice glaze.

    1. I wish I had your knowledge of glazes so I could better predict outcome. That said, I'm glad I tried this "tenmoku".
      Thanks for your words about the pumpkins. I've made them for several years and am pleased I took a chance and tried the different glazes this year. There is that experimental aspect to glazing that keeps the curiosity going.

  2. Love the pumpkins! The blue pumpkin won't be sitting on the shelf very long!
    I'm starting to test different iron saturated glazes on sofa feldspar clay bodies and finding it makes a big difference on how those glazes react.

    Just finished a testing round with iron reds and now testing whites..... it will never end :)

    1. No, it really doesn't end. It's an addiction. I really would like to streamline my glazes. Just don't know if I have the discipline.

  3. may not be as expected...but still good

    1. Thank you. Sometimes it is a good surprise.


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