mel jacobson on fri 12 may 06
the standard procedure for red that has been
touted now for a few years is:
down firing.
just reheat your kiln with fuel/oxidized for a half hour
at 1700+ bring the kiln back to 1900F and then
let it cool through that critical stage again.
red is all about cooling.
that is how the coleman ad with the entire kiln
full of bright red is done. it will work every time.
medium reduction throughout the kiln.
slow cool kiln.
a bit of re-fire.
bright red.
mel
from: mel/minnetonka.mn.usa
website: http://my.pclink.com/~melpots3
David Hendley on fri 12 may 06
Mel, if you fire down in a wood fired kiln, you end up
with....... rough spots all over the glazes where the ashes
did got trapped in the still-tacky glaze and did not have
a chance to melt. Maybe red, maybe not, often mottled
red and green together.
In my experience, and I have lots, if you miss the
reduction on the heating side of things you are SOL.
You can refire and slowly cool a failed copper red a
dozen times and you will still have a failed copper red.
Nothing you can do will ever give you red.
The critical period is before the glaze has sintered,
in the 1400 to 1800 degree range.
David Hendley
Maydelle, Texas
david(at)farmpots(dot)com
"EXTRUDE IT! Getting the Most From
Your Clay Extruder" available at
http://www.farmpots.com
----- Original Message -----
> the standard procedure for red that has been
> touted now for a few years is:
> down firing.
>
> just reheat your kiln with fuel/oxidized for a half hour
> at 1700+ bring the kiln back to 1900F and then
> let it cool through that critical stage again.
> red is all about cooling.
Rikki Gill on sat 13 may 06
Dear Ivor,
I am not sure I understand what you are saying.
I find that I get brighter colors, including reds and Shinos, if I oxidize
for 5 minutes or so after turning off my gas kiln at cone 10-11.
If I allow the carbon to leave the kiln it helps my colors. I fire copper
reds and Oribes in the same load. Not clearing the carbon
darkens the surface in my Olsen updraft.
Best, Rikki
www.rikkigillceramics.com
----- Original Message -----
From: "Ivor and Olive Lewis"
To:
Sent: Saturday, May 13, 2006 12:11 AM
Subject: Re: red glaze firing
Dear David Hendley,
Perhaps we should explain that it is essential for the reducing gases to
penetrate right through the unfired glaze to break down black(Cupric)copper
oxide before any melting happens. Given recipes that incorporate Borax frits
will start to sinter in the 700-800 deg C and be molten by about 1000 deg
then early reduction is necessary and should be maintained to maturity.
Once the glaze has achieved fusion it is difficult for any gas to diffuse
into the depth of the glaze. What I can imagine is that if the surface
oxidises during cooling would be that the colour would be subdued or
darkened due to complementary optical cancellation between red and green.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
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Ivor and Olive Lewis on sat 13 may 06
Dear David Hendley,
Perhaps we should explain that it is essential for the reducing gases to =
penetrate right through the unfired glaze to break down =
black(Cupric)copper oxide before any melting happens. Given recipes that =
incorporate Borax frits will start to sinter in the 700-800 deg C and be =
molten by about 1000 deg then early reduction is necessary and should be =
maintained to maturity.
Once the glaze has achieved fusion it is difficult for any gas to =
diffuse into the depth of the glaze. What I can imagine is that if the =
surface oxidises during cooling would be that the colour would be =
subdued or darkened due to complementary optical cancellation between =
red and green.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Ivor and Olive Lewis on mon 15 may 06
Dear Rikki Gill,
I think your post gives the reason for the increase in brilliance. If =
the surface of the glaze has a film of carbon covering it then a quick =
blase of hot oxygen will remove that surface discolouration.
But if you prolong the oxidation period you will oxidise the copper =
compound at the surface, but not necessarily the interior. It will turn =
green. Mix green and red and you get a grey, if the reflect is massive =
you can get a full bright green.
Scratching the surface of such a pot will often show the red under =
colour.
Hope that makes sense to you.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
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