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fwd: cone 6 glaze

updated wed 18 mar 98


Eric Alan Hansen on tue 17 mar 98

>Actually I'm firing to cone 8 currently
>but want to move it down little. Cone
>6 is more standard.
>I use a glaze with wood ash. I don't
>wash the ash, but I do screen it. The
>woodash has to be soft, white, fluffy.
>Not from a wood kiln! That kind is
>sintered and won't get the best results.
>You can tell it will feel crispy at
>woodash 50
>ochre 25
>custer 25
>Seems to be better on porcelain. Some-
>times bright yellow, sometimes browner
>depends on mineral content of the ash
>which varies from wood to wood. Darker
>and more opaque where thin goes to
>almost black. Yellow where thicker.
>Keep glaze thin or you will be scraping
>shelves. Becomes transparent yellowish
>brown and very fluid when thickly applied.
>The mid way thin/thick of application is
>mottled like a salt fired piece and is
>satin matte. But I got great reds,
>yellows, browns, blacks on pieces where
>it's thinner. To make tiny rivers of ash
>I make the same glaze substituting Red
>Art for the Ochre and trail it on with
>a slip trail bulb. Caution: use rubber
>gloves with unwashed ash glazes or face
>the possibility of contact dermatitis.
>It will mildly burn the skin. I keep
>Cornhuskers lotion and Hydrocortisone
>cream around the house anyway. I layer
>it with a glossy, glassy glaze that
>by itself has its own problems like
>keeping me up at night to the sound
>of loudly cooling and crazing *pings*:
>Wood ash 19.5
>Barnard Slip Clay 16.5
>Custer 23
>Gerstley Borate 11
>Barium Carbonate 8
>Zinc 3
>plus Copper Carbonate 1.5
>Needs to be corrected for fit and pinholes
>but every clay body is a different can of
>worms. The barium/boron eutectic makes it
>hard to say what cone this fires to - the
>longer it is in kiln or the greater the
>thermal mass of the kiln the more it will
>flux. Formulated originally without the
>ash or slip clay it was semi-satin, semi-
>gloss somewhere around cone 2. Boron
>subdues the copper coloration.
>Custer 35
>Gerstley 17
>Barium Carb 12
>Zinc Ox 5
>plus as much local dark red clay as I
>can get into it. Then I layer over it
>with the same glaze without the clay.
>This gets a highly pitted chocolate
>cake look with a cratered & pinholed
>glossy surface.
>I don't like any of the above glazes
>inside a bowl. I kinda like more of a
>feldspathic glaze for eating/drinking
>surface. So here are some regular
>CORNBALL WHITE - cone 6 ox
>Cornwall Stone 45.61
>OM4 21.27
>Talc 6.73
>Whiting 7.15
>Barium 11.88
>KONA WHITE - cone 6 ox
>Kona F-4 41.03
>Cornwall Stone 41.03
>Wollastonite 1.10
>Barium Carb 3.33
>Zinc Ox 2.19
>PERMANENT TAN - cone 6 ox
>Wollastonite 30.33
>Talc 8.88
>Spodumene 49.77
>EPK 11.02
>As I remember they were all quite nice.
>But these and about half a dozen other
>tests went into a bucket of "mystery
>glaze" liner to which I added even more
>Custer, Kona F-4, EPK, then came in
>later with scoops of Gerstley and
>zircopax for a really nice satin with
>no problems. I need to find a Mac up at
>KU that has the HyperglazeIIx on it with
>my files to reconstruct. But it may not
>be worth it. That concept is simple if
>ya know how to use the program and
>maximize the feldspars, lithium, KNaO
>and get plenty of other fluxes in each
>Also I did not know Clayart has 1995
>archives under the subject: cone 6
>chit-chat. With several hundred recipes.
>I'm editing out all the headers
>and putting in titles and a single
>style much like this here.
>Some very lively conversation is
>recorded in the archives about cone
>6 favorites. I am enjoying reading it
>now. Basically that was what I was after
>but if anyone wants to bounce some
>ideas, info, I will play. One more:
>BULLFROG GREEN - cone 5 ox
>Custer 47
>Whiting 7.5
>Barium Carbonate 10.5
>Zinc Oxide 6
>OM4 5
>EPK 5
>Flint 19
>Copper Carbonate 4
>I like a lot of green. But this ain't
>no Kermit green. Very stony matte with
>very hard surface. I suspect it was a
>tile glaze. Joe Zeller supplied the base,
>I went ape with the copper.
>I'm not taking responsibility for anyone
>using these glazes, etc. Something is
>probably toxic. They are examples of my
>research and they work out in formulation.
>Which is what they are examples of.
>So go formulate your own non-toxic glazes,
>if that is possible. It's probably bad
>for the environment too. Email me with
>questions as to household performance, as
>that may be indicative of other problems.
>The badly crazed surfaces are not considered
>to be a continous-non porous sanitary
>Eric Hansen, Lawrence, Kansas

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