Munsoor S. Malik on sun 22 feb 98
I made my first foray into saggar firing and it was excellent; creamy
background, pink and orange blushes where the flowers were. I used a
bottle shaped vase made with raku clay, terra sigillata and burnished
it. I felt "that's it, I know how to do this!"
I came crashing back to earth as all subsequent attempts have failed
miserably. This is where I need help:
1. The saggar firings nowhave at best a dirty whitish background with
faint traces of pinks and orange, mostly black around the base.
2. The ash does not seem as completely burnt as in my first
successful effort. The burnt flowers still can be discerned. In my
first sttempt the flowers burnt completely.
* Does the saggar need a lot of space internally around the pot?
* Should the bricks be really tight around each other with minimal
air holes?
* I am using a converted electric kiln that uses a single venturi
burner, There is very little space around the saggar which is made
of soft and hard firebrick with a kiln shelf capping it. Does this
reduced space affect the firing?
* What temperature should I take this to? On my only successful
firing I took the kiln to an indicated temperature of 925 degrees
C. The books I have say the internal temperature in the saggar is
lower. There is very little space around the thermocouple because
of the space the saggar occupies so I need to determine a better
way of guaging the temperature, the air flow may be affected(?).
* The combustible material was the same in all cases; oxides, salts,
sawdust, flowers, leaves and weeds.
* Can you refire a saggar fired pot?
* Does the shape effect how the colors manifest themselves? Will an
open shape be less likely to work then a closed shape?
* What temperatures do the colors set on the ware?
* Should the kiln be sealed up at the flue and burner ports after
firing?
I would appreciate any help the experts out there can give me. Thanks
in advance,
I keep reminding my self.........it worked once!!
Rubina Malik
Karen Terpstra on mon 23 feb 98
Rubina, Keep trying! This is the mystique, suprise, and uniqueness of
saggar firing--it's never the same. I'm far from being an expert but
here are a few guesses. It sounds like the inside of the saggar isn't
reaching a high enough temperature from your description of the terra
sig. The combustables left charcoal around the base then didn't reach a
high enough temp to burn off. Yes, it's usually true the inside of the
saggar is lower. The brick and sometimes the combustibles such as
sawdust act as insulation. I usually fire the kiln 3-4 cones hotter
than what I'm trying to reach inside the saggar. If I'm using terra
sigs, I put a cone 6 or 7 on the top of the saggar and hope the interior
averages around cone 3. The inside temp varies greatly due to how
tightly you pack the saggar. I like to pack it a little on the loose
side--it needs oxygen to burn. Yes, air flow from the burner ports to
the flue can be affected; if the saggar is too large you may not have
the circulation you need in the kiln. I like the bricks fairly tight,
however sometimes I leave a crack in front of the spy hole so I can see
(and smell)whats going on during the firing and I use old hard bricks so
its never real tight which is a "good thing", you need circulation
inside the saggar too so the stuff will burn. I let the kiln soak for a
2-3 hours as soon as I smell the stuff start to burn or if I can see a
flame inside the saggar then fire it off. I don't think the shape of
your ware matters as long as you pack the saggar so some of the "juicy
stuff" sets right on the work. The possibilities in saggar firings are
endless. It takes alot of experimenting with woods, hay, straw, bannana
peels, or what ever you can think of or get your hand on. You might try
stratigically placing a hedge apple (flowers-whatever) on a platter or
sprinkling soda ash and copper carb on top of the wood letting it settle
where it may when the combustables burn down. Many of the materials
that you mentioned will look different on the work when fired to
different temps. This is the beauty and intrique of saggar firing.
It's never the same. Yes you can refire the work and try it alittle
hotter. I don't bother sealing up the kiln after firing a saggar; the
bricks are already around the work and I've tried it both ways and
couldn't see a difference. Good Luck!
Karen Terpstra
Munsoor S. Malik wrote:
>
> ----------------------------Original message----------------------------
> I made my first foray into saggar firing and it was excellent; creamy
> background, pink and orange blushes where the flowers were. I used a
> bottle shaped vase made with raku clay, terra sigillata and burnished
> it. I felt "that's it, I know how to do this!"
>
> I came crashing back to earth as all subsequent attempts have failed
> miserably. This is where I need help:
>
> 1. The saggar firings nowhave at best a dirty whitish background with
> faint traces of pinks and orange, mostly black around the base.
> 2. The ash does not seem as completely burnt as in my first
> successful effort. The burnt flowers still can be discerned. In my
> first sttempt the flowers burnt completely.
>
> * Does the saggar need a lot of space internally around the pot?
> * Should the bricks be really tight around each other with minimal
> air holes?
> * I am using a converted electric kiln that uses a single venturi
> burner, There is very little space around the saggar which is made
> of soft and hard firebrick with a kiln shelf capping it. Does this
> reduced space affect the firing?
> * What temperature should I take this to? On my only successful
> firing I took the kiln to an indicated temperature of 925 degrees
> C. The books I have say the internal temperature in the saggar is
> lower. There is very little space around the thermocouple because
> of the space the saggar occupies so I need to determine a better
> way of guaging the temperature, the air flow may be affected(?).
> * The combustible material was the same in all cases; oxides, salts,
> sawdust, flowers, leaves and weeds.
> * Can you refire a saggar fired pot?
> * Does the shape effect how the colors manifest themselves? Will an
> open shape be less likely to work then a closed shape?
> * What temperatures do the colors set on the ware?
> * Should the kiln be sealed up at the flue and burner ports after
> firing?
>
> I would appreciate any help the experts out there can give me. Thanks
> in advance,
>
> I keep reminding my self.........it worked once!!
>
> Rubina Malik
Dannon Rhudy on mon 23 feb 98
It seems likely that your subsequent firings have not gotten as
hot as the first. Too low a temperature will usually produce
muddy or no color, with the work tending toward smoky smudges,
etc.
* Does the saggar need a lot of space internally around the
pot?
No, it only needs enough space to contain the pot and the
combustibles.
* Should the bricks be really tight around each other with
minimal air holes?
Generally, a tight saggar is preferable. Seal it with clay.
* I am using a converted electric kiln that uses a single
venturi burner, There is very little space around the saggar
which is made of soft and hard firebrick with a kiln shelf capping
it. Does this reduced space affect the firing?
Small space does not affect it.
* What temperature should I take this to? On my only
successful firing I took the kiln to an indicated temperature of
925 degrees C.
I usually take saggar fires to about 012 or so, though many fire
much lower and get decent color.
* The combustible material was the same in all cases; oxides,
salts, sawdust, flowers, leaves and weeds.
Those are pretty standard. You could add some dry manure to
that, or most anything.
* Can you refire a saggar fired pot?
Yes, but the chance of breakage increases on second firing.
However, if you don't like it the way it is, do it over.
* Does the shape effect how the colors manifest themselves?
The shape does not matter.
* Should the kiln be sealed up at the flue and burner ports after
firing?
It could not hurt, but probably does not matter much. Might
get better blacks, but not at higher temperatures, because the
combustibles are long since combusted, as it were.
Saggar firing and pit firing are chancy affairs. More experience
will give you better chances for regular success, however you
measure that success. Just keep on doing it.
Dannon Rhudy
potter@koyote.com
| |
|
