Phil Smith on mon 24 mar 03
Hi Folks,
I've read that Zinc Oxide Volatilizes completely in high fire
reduction. Yet some of my favorite Reduction glazes contain it.
Is the Zinc there for oxidation firing?.
Is there a purpose for the Zinc in cone 10 Reduction?.
Seems a waste if it's only function is to be blown out the stack.
Phil...
Earl Brunner on mon 24 mar 03
It is generally considered to go up the stack in reduction, what ISN"T
clear is what affect it has on the glaze before it goes up the stack.
If I remember right, the general consensus was to make two test batches
of the individual glaze, one with and one without the zinc and then see
fi there is a difference in your firing results.
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Phil Smith
Sent: Sunday, March 23, 2003 10:44 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Zinc Oxide in Reduction?
Hi Folks,
I've read that Zinc Oxide Volatilizes completely in high fire
reduction. Yet some of my favorite Reduction glazes contain it.
Is the Zinc there for oxidation firing?.
Is there a purpose for the Zinc in cone 10 Reduction?.
Seems a waste if it's only function is to be blown out the stack.
Phil...
David Hendley on tue 25 mar 03
I'm all for learning theory, but reality is what is important to me.
The reality is that zinc oxide does, indeed, have an effect on some cone
10 reduction glazes. A few years ago, I tested 6 glazes with high
percentages of zinc oxide (at least 4%), with and without the zinc.
In half of the cases, there were discernable differences in the zinc/ no
zinc tests (no differences were noticeable in the other half).
So, there is some purpose for zinc oxide to be in some cone 10
reduction glazes, even if the theory says that it ends up going out
the exit flue.
The smart thing to do is to test your glaze with and without the
zinc, so you won't be wasting it if it has no effect.
David Hendley
Maydelle, Texas
david@farmpots.com
http://www.farmpots.com
----- Original Message -----
> Hi Folks,
> I've read that Zinc Oxide Volatilizes completely in high fire
> reduction. Yet some of my favorite Reduction glazes contain it.
> Is the Zinc there for oxidation firing?.
> Is there a purpose for the Zinc in cone 10 Reduction?.
> Seems a waste if it's only function is to be blown out the stack.
> Phil...
>
Charles Moore on tue 25 mar 03
David and others,
I wonder what the effect of ^6 reduction is on zinc oxide. Anyone know?
Charles
Sacramento
----- Original Message -----
From: "David Hendley"
To:
Sent: Tuesday, March 25, 2003 8:06 AM
Subject: Re: Zinc Oxide in Reduction?
> I'm all for learning theory, but reality is what is important to me.
> The reality is that zinc oxide does, indeed, have an effect on some cone
> 10 reduction glazes. A few years ago, I tested 6 glazes with high
> percentages of zinc oxide (at least 4%), with and without the zinc.
> In half of the cases, there were discernable differences in the zinc/ no
> zinc tests (no differences were noticeable in the other half).
> So, there is some purpose for zinc oxide to be in some cone 10
> reduction glazes, even if the theory says that it ends up going out
> the exit flue.
> The smart thing to do is to test your glaze with and without the
> zinc, so you won't be wasting it if it has no effect.
> David Hendley
> Maydelle, Texas
> david@farmpots.com
> http://www.farmpots.com
>
>
>
>
> ----- Original Message -----
> > Hi Folks,
> > I've read that Zinc Oxide Volatilizes completely in high fire
> > reduction. Yet some of my favorite Reduction glazes contain it.
> > Is the Zinc there for oxidation firing?.
> > Is there a purpose for the Zinc in cone 10 Reduction?.
> > Seems a waste if it's only function is to be blown out the stack.
> > Phil...
> >
>
>
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Mondloch on thu 27 mar 03
The last time this was discussed, I was in the process of struggling to get
my ^10 high zinc rutile blue to work in a new gas kiln. I tried removing
the zinc ( didn't work) and then adjusting the firing schedule for that and
other considerations. It's working now (knock on wood) with the following
firing schedule.
Overnight candle. Damper full open and slow up to ^08 with a one hour soak.
20 minute body redux at .65 oxy probe ( important I think- I do not let the
temp rise over 1740F during this reduction.) Damper out to .08 oxy probe
until ^6 when I do another 20 minute redux. Damper out to .08 oxy until ^9.
Turn burners down and soak for about an hour at lower temp until ^10 bends.
During this soak time I stoke some wood sticks with resulting short periods
of reduction. Shut down with damper slightly open.
I think the important thing for my zinc glaze is stopping the body redux at
1740F. According to my Hammer book, that's the temp when zinc metal boils
off . When I stayed in reduction after body reduction I had the tell-tale
yellowish powder on the underside of the metal damper. I don't get that now.
My guess on why I don't lose the zinc during reduction after ^6, is that the
zinc is held in the melt then.
Sylvia
---
Mark & Sylvia Mondloch
Silver Creek Pottery & Forge
W6725 Hwy 144
Random Lake ,Wi 53075
HotArt@silvercreekpottery.com
http://www.silvercreekpottery.com
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