Snail Scott on sat 15 jan 05
At 01:00 PM 1/15/2005 -0600, you wrote:
>So...there appears to be a bit of a trick in glazing, after you've bisque
>fired the pots. Zamek says you can dip, pour, spray or brush the glaze
>on...but others have had problems losing the dendritic aspect of the
design...
It's all in the recipe. Some glazes dissolve the
colorants and let them move, and some don't. It's
something I've seen often with underglaze pencil
drawing, for instance. When I test a clear or
semi-transparent glaze, I generally put swipes of
several colors across the test tile, to see what
happens: big differences, both in the tendency of
the color stripe to retain its distinctness and
also its rendering of the intended color. I can't
make any specific suggestions, as I've never
tried to correlate it to any particular chemistry
and I don't work often in earthenware. Do plan on
testing your samples with multiple glaze recipes,
though; I'm betting that you'll find one that works
better than others.
-Snail
Kate Johnson on sat 15 jan 05
Hi all,
and thanks Lili, just got the Xerox in the mail about mochaware--that's one
I didn't have, sure enough.
I have mentions of this technique in several of my books, and have test
tiles in the kiln now, plus a nice plate waiting to see how the test tiles
come out.
I found tobacco juice to work much better than vinegar, for whatever reason,
cigar juice to work better than cigarette, and manganese dioxide to work
_longer_ than a red iron oxide colorant. (It's my understanding that you
need to ditch the mocha tea after two weeks thereabouts, anyway, but this
was only a few days later and the red didn't want to make ferms as it had at
first....)
I also found that I didn't mind the smell...go figure...
BUT. I do have a question that I've discussed offlist with several other
clayart members who have tried this technique. I looked in the archives and
didn't see this specific difficulty addressed, so wondered if anyone has
experience with it. That is, in glazing, the fern-like fronds disappear,
soften, blur, etc. I'd like to avoid that!
As you probably know, the mocha tea recipe is usually some variation of
water, tobacco (or vinegar or other acid), and colorant--manganese, cobalt,
red ox, whatever.)
Jeff Zamek's, for black dendritic slip, is
20 grams Manganese Dioxide powder
29 grams water
29 grams apple cider vinegar
1 cigarette (I used a quarter of a cigar)
Jo Connell's book doesn't suggest using vinegar with the tobacco, and I
believe it was her recipe I used.
At any rate, I got gorgeous, exciting results, as you can see at fifth row
up from the bottom in my Pottery in Progress album,
http://pg.photos.yahoo.com/ph/graphicartepsi/album?.dir=bbb8 ! And I'd
prefer not to mess it up now...
So...there appears to be a bit of a trick in glazing, after you've bisque
fired the pots. Zamek says you can dip, pour, spray or brush the glaze
on...but others have had problems losing the dendritic aspect of the design.
He doesn't mention any problems in this process, nor have any of the books
or articles I've looked at.
One offlist poster and I have been discussing whether there might be some
binder used in the mocha tea--a tiny bit of frit, a wee bit of clay,
perhaps, in order to make it stay during firing?
Has ANYONE else out there run into this problem and solved it, that might we
willing to share the secret?
Thank you!
Best--
Kate
| |
|
