Nancy on sun 14 jan 07
Hi everyone!
Well I am going to try woodfiring, not my own kiln, but my supplier is
firing in May and I have purchased a 21"x16"x9" shelf space. Now I have
never woodfired. I am getting 25lbs of clay and the shino liner glaze
they are using. I searched the archives and google for almost 3 hours
tonight to find very little information and thought some of you woodfire
gurus could help me out with some advice. I understand the process of
the firing and the wood ash and the glazing and even read a little about
flashing, though I don't really get that yet.
so here are a few things I am wondering.
1. Can I add some oxides to my pieces to help with the "flashing". Is
is a waste of my time? I'm thinking chrome oxide, cobalt oxide, tin
oxide, manganese dioxide, zince oxide (i think that is all I have). Or
are there other chemicals I can use to enhance the piece?
2. should I throw these pieces thicker than I would for my electric
kiln or the same? is the similar to saggar firing where I have to be
careful if I add knobs, handles, etc.
3. If I throw a covered jar will the inside be unglazed or should I use
the liner glaze on the inside and are the top and bottom fired together?
4. can your recommend types of pieces I should throw for my first try
at this?
Thanks in advance for taking the time to help me out with this.
Nancy
www.hilltoppottery.com
L. P. Skeen on sun 14 jan 07
Hey Nancy,
I can't answer #1 for sure, but Gary Holt could..., but for #2a, the
answer is, throw just your regular ware. I have seen paper thin
porcelain come out of a wood kiln; your work doesn't have to be thicker
for a wood firing. It DOES have to be big enough not to blow off the
shelf or into someone else's work tho, LOL.
For #2b, No. Wood fired work is usually fired to stoneware
temperatures. As long as your handles are securely in place as they
should be in any case, they are not likely to fall off.
3a. The inside will be unglazed unless you put a glaze on it; this is
the meaning of "liner glaze", which you said you are purchasing from the
supplier. If you leave it unglazed, you'll get a little flashing
inside, but it won't get enough of the ash coating you'd need to be
called a "glaze", and even if you did, it's not likely to be as smooth
as I personally prefer the inside of a jar to be.
3.b. The top and bottom will be fired together, but they will be
separated by what is called wadding, which if I remember right is
alumina hydrate and something else (I forget what, possibly fireclay?)
mixed to a clay consistency and made into little balls. You put the
little balls underneath every pot, like feet, so the ash flying around
doesn't make your pots one with the shelf they're sitting on. You will
also put wads in the lid gallery, and the lid on top of that. You may
have noticed on some woodfired pots, these haloed round spots around the
base of them, or sometimes, folks will fire pots stacked on top of each
other, and there will be wad marks where they were stacked. Wads can
make some interesting marks. Anyway, the wadding and de-wadding
processes are the most tedious part of any wood firing, IMO.
4. Figure out your space by making a cardboard cutout of the shelf
size, and stack up some kiln posts so you can see the height you are
allowed. Now make whatever you would like to fill the space. Plates
take up more room, but can be stacked with wadding if you want to make
plates. Since this is your first wood fire, I'd go with some
vase/bottle forms, a casserole (small), tumblers, tall lidded jar, etc.
DON"T waste your vertical space; if you paid for it, USE IT. Don't
crowd your pieces too much either, or they won't have room for ash to
fly around. I'd say allow an inch or a bit more around each piece.
(YMMV and other more experienced folks will have other opinions.)
You do realize that you can glaze the outsides of your pots as well as
the insides don't you? If they're ONLY doing wood and not salt, I'd put
some glaze on the exterior surfaces. If they're doing salt, however,
I'd do a few with glaze and a few without. :) Copper reds look amazing
in wood fire, as do shinos. YUM - big fat shiny crackly shino.... Good
luck and be sure to post pix on teh flickr site.
L
Nancy wrote:
> 1. Can I add some oxides to my pieces to help with the "flashing". Is
> is a waste of my time? I'm thinking chrome oxide, cobalt oxide, tin
> oxide, manganese dioxide, zince oxide (i think that is all I have). Or
> are there other chemicals I can use to enhance the piece?
>
> 2. should I throw these pieces thicker than I would for my electric
> kiln or the same? is the similar to saggar firing where I have to be
> careful if I add knobs, handles, etc.
>
> 3. If I throw a covered jar will the inside be unglazed or should I use
> the liner glaze on the inside and are the top and bottom fired together?
>
> 4. can your recommend types of pieces I should throw for my first try
> at this?
>
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