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new ^6 fake ash!

updated fri 5 may 00


Evan Dresel on thu 4 may 00

Pulled a luscious cruet out of the kiln last weekend. It is glazed on
the outside with a golden coloured fake ash with some wax resist
decoration. It was near the top of the kiln so I was dancing around
playing show-and-tell even before I got the rest unloaded. Which is a
good thing because the bottom shelf ended up underfired.

I've been working on this fake ash glaze for a little while and am
excited to share it with you all -- even if I don't seem able to muster
much dignified humility. The glaze is actually the New Tyler Amber
glaze from Richard Zakin's Electric Kiln Ceramics book with 25 % by
weight dolomite added. It's a lot like the golden fake ash posted to
ClayArt a few years ago. I actually fired to cone 5 but my previous
test tile was closer to ^6. It did pinhole on the underfired shelf so
I'm going to start creeping my temperature back up. I soak for 30-60
minutes and that seems to give me some bend in both the ^5 and ^6 cones.
I recalculated the recipe below to add up to 100.

The glaze has passed 3 freeze-boils and doesn't contain any
particularly nasty constituents (in my opinion). It hasn't been tested
for leaching but I don't think I'd use use this glaze on a
liquid-contact surface anyway for aesthetic as well as practical
reasons. I imagine you could reformulate without the gerstley borate
but I'm not going to bother until I get more experience with it as is.
As always, test -- your mileage may vary.

New Tyler Fake Ash (Thanks Richard and whoever Tyler is!)
^5-6 oxidation

Ferro Frit 3110 16
Cedar Heights Red Art Clay 48
Gerstley Borate 16
Dolomite 20

Total 100

Do you glaze wizards think this is too low in Si and Al? Also the
expansion seems to calculate as too high which seems weird since I
just added Ca and Mg. As I said, it hasn't crazed on my clay body so I
assume it has something to do with the microcrystals.

-- Evan in W. Richland WA who just got a nicely illustrated invitation
to the Upper St. Croix Valley Potters (Minnesota) annual studio tour.
Wow! Anyplace that has that many wonderful potters must be doing
something right. I like the way most of the potters have work by guest
artists at their studios, too. Too bad it's so far away but with luck
I'll make it to the Oregon Potters Association sale next Sunday.