Chess Denman on fri 10 sep 99
I am still very inexperienced with copper reds and would appreciate some
advice. Out of the last four firings one produced red bits, in one red went
fine and in two all copper red was absent.
I use three recipies for copper red which are adaptations of american
recipies to my english purposes they are:-
++++++++++++++++++++++++
+++ Lewis Red LR +++
++++++++++++++++++++++++
Firing type: Reduction
Glaze type: Copper red
Date: 11/29/98
Cornwall Stone 30 30.9% Hazard!
Barium carbonate 49 50.5% Hazard!
Silica 10 10.3% Hazard!
Tin oxide 5 5.2%
Bentonite 3 3.1% Hazard!
-------- ------
97 100 %
Black copper oxide 0.64 0.7% Hazard!
++++++++++++++++++++++++++++++++++
+++ Pete's copper red. PCR +++
++++++++++++++++++++++++++++++++++
Firing type: Reduction
Glaze type: Copper red
Date: 11/29/98
Nepheline syenite 56 55.4%
Silica 22 21.8% Hazard!
Gerstley borate 10 9.9%
Whiting 12 11.9%
Tin oxide 1 1 %
-------- ------
101 100 %
Black copper oxide 0.19 0.2% Hazard!
++++++++++++++++++++++++++++++++++++
+++ Copper red (Oxblood) CRO +++
++++++++++++++++++++++++++++++++++++
Range: 9
Firing type: Reduction
Glaze type: Copper red (Oxblood)
Color: turquoise green with hint of red
Surface: Gloss
Transparency: Opaque
Date: 08/18/98
Cornwall Stone 54.74 54.7% Hazard!
Potash feldspar 10.53 10.5%
Barium carbonate 34.74 34.7% Hazard!
-------- ------
100 100 %
Black copper oxide 2.11 2.1% Hazard!
I thought it was temperature then I thought it was not enough reduction then
I thought I would put transparent glaze on top to protect them............
However.
1 Firing cycle is now constant and regular
8 hours to cone 9 down with a soak at the end to acheive this at 1260.
2 Putting a transparent glaze over the top works to preserve reds in firings
where the unprotected surface has no red. But in the firings where lots of
things went red it makes a kind of pink frothy effect (?too much allumina)
3 In the firing that worked best I had smoke from the kiln
4 I have just started using an oxyprobe and in the last firing which
produced no red on almost everything at all except the protected half of a
test plate the reduction used was intense - almost "off the scale" but no
smoke. Also the flame from the peep hole was 4"long and green!!!!!!!!!!
Ok this is my hypothesis.
Far from having insufficient reduction I have too much on the firings which
dont work.
The smoky firing was good because smoke means poor reduction - burning isnt
good enough even to produce CO.
So, Was I literally burning off copper into the flame last time? Could one
burn it all out and is that why some firings don't prooduce reds? Or am I
barking up the wrong tree.
Doubtless red experts will sigh and say here we go again but please, be
indulgent,
Chess
Ammateur trying to be scientific sort of.
Nils Lou on sat 11 sep 99
One thing you might try, Chess is: After applying the copper red glaze
spray or dip a THIN coat of any 06 clear glaze. This will prevent
volitalizing of your copper. Also, it is important to have reduction early
in the firing starting at C010. It does not have to be heavy, but early is
good. Let us know if you try it and if it helps. NL
On Fri, 10 Sep 1999, Chess Denman wrote:
> ----------------------------Original message----------------------------
> I am still very inexperienced with copper reds and would appreciate some
> advice. Out of the last four firings one produced red bits, in one red went
> fine and in two all copper red was absent.
> I use three recipies for copper red which are adaptations of american
> recipies to my english purposes they are:-
>
> ++++++++++++++++++++++++
> +++ Lewis Red LR +++
> ++++++++++++++++++++++++
>
> Firing type: Reduction
> Glaze type: Copper red
> Date: 11/29/98
>
> Cornwall Stone 30 30.9% Hazard!
> Barium carbonate 49 50.5% Hazard!
> Silica 10 10.3% Hazard!
> Tin oxide 5 5.2%
> Bentonite 3 3.1% Hazard!
> -------- ------
> 97 100 %
>
> Black copper oxide 0.64 0.7% Hazard!
>
>
> ++++++++++++++++++++++++++++++++++
> +++ Pete's copper red. PCR +++
> ++++++++++++++++++++++++++++++++++
>
> Firing type: Reduction
> Glaze type: Copper red
> Date: 11/29/98
>
> Nepheline syenite 56 55.4%
> Silica 22 21.8% Hazard!
> Gerstley borate 10 9.9%
> Whiting 12 11.9%
> Tin oxide 1 1 %
> -------- ------
> 101 100 %
>
> Black copper oxide 0.19 0.2% Hazard!
> ++++++++++++++++++++++++++++++++++++
> +++ Copper red (Oxblood) CRO +++
> ++++++++++++++++++++++++++++++++++++
>
> Range: 9
> Firing type: Reduction
> Glaze type: Copper red (Oxblood)
> Color: turquoise green with hint of red
> Surface: Gloss
> Transparency: Opaque
> Date: 08/18/98
>
> Cornwall Stone 54.74 54.7% Hazard!
> Potash feldspar 10.53 10.5%
> Barium carbonate 34.74 34.7% Hazard!
> -------- ------
> 100 100 %
>
> Black copper oxide 2.11 2.1% Hazard!
>
> I thought it was temperature then I thought it was not enough reduction then
> I thought I would put transparent glaze on top to protect them............
> However.
> 1 Firing cycle is now constant and regular
> 8 hours to cone 9 down with a soak at the end to acheive this at 1260.
> 2 Putting a transparent glaze over the top works to preserve reds in firings
> where the unprotected surface has no red. But in the firings where lots of
> things went red it makes a kind of pink frothy effect (?too much allumina)
> 3 In the firing that worked best I had smoke from the kiln
> 4 I have just started using an oxyprobe and in the last firing which
> produced no red on almost everything at all except the protected half of a
> test plate the reduction used was intense - almost "off the scale" but no
> smoke. Also the flame from the peep hole was 4"long and green!!!!!!!!!!
>
> Ok this is my hypothesis.
> Far from having insufficient reduction I have too much on the firings which
> dont work.
> The smoky firing was good because smoke means poor reduction - burning isnt
> good enough even to produce CO.
>
> So, Was I literally burning off copper into the flame last time? Could one
> burn it all out and is that why some firings don't prooduce reds? Or am I
> barking up the wrong tree.
>
> Doubtless red experts will sigh and say here we go again but please, be
> indulgent,
>
> Chess
> Ammateur trying to be scientific sort of.
>
Dannon Rhudy on sat 11 sep 99
>----------------------------Original message----------------------------
>I am still very inexperienced with copper reds and would appreciate some
>advice. Out of the last four firings one produced red bits, in one red went
>fine and in two all copper red was absent.
>--------------------------------------------------------------
Your difficulties are much more likely to be the way you fire than
the glaze(s) you are firing. Pete's Red, at least in my experience, is
extremely reliable.
Try beginning your initial light to moderate kiln reduction at
about cone 012 to 010. Perhaps 45 minutes to an hour. Then
continue to raise the kiln temp until you reach your target cone.
I keep mine in light reduction all the way up, but you needn't. Do
begin reduction again when your target cone is bending, and
keep it in reduction until you've reached temp. Then, and this
may be the most important point: SLOW DOWN THE COOLING
time. Copper reds appear during COOLING, and if the kiln
cools too quickly, you may not get good or consistent reds. There
are numerous articles concerning copper reds. Among the easiest
to understand are two fairly recent (within the year) articles in Clay Times,
by Pete Pinnell. Or get/read Tichane's book on copper reds, for a
really in-depth look.
Regards,
Dannon Rhudy
potter@koyote.com
At 12:10 PM 9/10/99 EDT, you wrote:
Dennis McAvoy on sun 12 sep 99
My experience with copper reds says the glaze has to be applied in a thick
coating. I use a lot of Pete's Red and if it is put on thin it just doesn't
tern red. Hope this helps.
Dennis
Smoky Mountain Pottery
Gatlinburg, TN
maker of pots, plaques and custom stamps
gwalker on sun 12 sep 99
You are absolutely right, Dannon.
I have been firing copper reds for 30 years. The first 10 at 1100 deg C,
the last 20 at 1300 deg. C., but it is only recently that I have
discovered that by far the most critical factor is the cooling. This
should be as slow as possible right down to 700 deg. C. I DO think you
can have too much reduction ... light seems to work best for me from 900
deg. C. through to the end and then simply shut down and clamp kiln.
I will admit, though, that the factors influencing the colour are
miriad.
Good luck,
Geoff. On the Glorious Gold Coast. A more perfect day no-one could ever
wish for.
Dannon Rhudy wrote:
> ----------------------------Original
> message----------------------------
>
> >----------------------------Original
> message----------------------------
> >I am still very inexperienced with copper reds and would appreciate
> some
> >advice. Out of the last four firings one produced red bits, in one
> red went
> >fine and in two all copper red was absent.
> >--------------------------------------------------------------
>
> Your difficulties are much more likely to be the way you fire than
> the glaze(s) you are firing. Pete's Red, at least in my experience,
> is
> extremely reliable.
>
> Try beginning your initial light to moderate kiln reduction at
> about cone 012 to 010. Perhaps 45 minutes to an hour. Then
> continue to raise the kiln temp until you reach your target cone.
> I keep mine in light reduction all the way up, but you needn't. Do
> begin reduction again when your target cone is bending, and
> keep it in reduction until you've reached temp. Then, and this
> may be the most important point: SLOW DOWN THE COOLING
> time. Copper reds appear during COOLING, and if the kiln
> cools too quickly, you may not get good or consistent reds. There
> are numerous articles concerning copper reds. Among the easiest
> to understand are two fairly recent (within the year) articles in Clay
> Times,
> by Pete Pinnell. Or get/read Tichane's book on copper reds, for a
> really in-depth look.
>
> Regards,
>
> Dannon Rhudy
> potter@koyote.com
>
> At 12:10 PM 9/10/99 EDT, you wrote:
Mike Bailey on mon 13 sep 99
In message , Chess Denman writes
Dear Chess,
I seemed to me that the main firing factors for getting reds were:
1. Starting the reduction earlier than 950 - maybe 850 deg C.
2. Maintaining reduction throughout the firing - it needed be heavy but
there.
3. A reasonably fast cool to stop re-oxidation.
Looking at your recipes you're presumably interested in mattish glazes.
Cheers,
Mike.
>----------------------------Original message----------------------------
>I am still very inexperienced with copper reds and would appreciate some
>advice. Out of the last four firings one produced red bits, in one red went
>fine and in two all copper red was absent.
>I use three recipies for copper red which are adaptations of american
>recipies to my english purposes they are:-
>
>++++++++++++++++++++++++
>+++ Lewis Red LR +++
>++++++++++++++++++++++++
>
>Firing type: Reduction
>Glaze type: Copper red
>Date: 11/29/98
>
> Cornwall Stone 30 30.9% Hazard!
> Barium carbonate 49 50.5% Hazard!
> Silica 10 10.3% Hazard!
> Tin oxide 5 5.2%
> Bentonite 3 3.1% Hazard!
> -------- ------
> 97 100 %
>
> Black copper oxide 0.64 0.7% Hazard!
>
>
>++++++++++++++++++++++++++++++++++
>+++ Pete's copper red. PCR +++
>++++++++++++++++++++++++++++++++++
>
>Firing type: Reduction
>Glaze type: Copper red
>Date: 11/29/98
>
> Nepheline syenite 56 55.4%
> Silica 22 21.8% Hazard!
> Gerstley borate 10 9.9%
> Whiting 12 11.9%
> Tin oxide 1 1 %
> -------- ------
> 101 100 %
>
> Black copper oxide 0.19 0.2% Hazard!
>++++++++++++++++++++++++++++++++++++
>+++ Copper red (Oxblood) CRO +++
>++++++++++++++++++++++++++++++++++++
>
>Range: 9
>Firing type: Reduction
>Glaze type: Copper red (Oxblood)
>Color: turquoise green with hint of red
>Surface: Gloss
>Transparency: Opaque
>Date: 08/18/98
>
> Cornwall Stone 54.74 54.7% Hazard!
> Potash feldspar 10.53 10.5%
> Barium carbonate 34.74 34.7% Hazard!
> -------- ------
> 100 100 %
>
> Black copper oxide 2.11 2.1% Hazard!
>
>I thought it was temperature then I thought it was not enough reduction then
>I thought I would put transparent glaze on top to protect them............
>However.
>1 Firing cycle is now constant and regular
>8 hours to cone 9 down with a soak at the end to acheive this at 1260.
>2 Putting a transparent glaze over the top works to preserve reds in firings
>where the unprotected surface has no red. But in the firings where lots of
>things went red it makes a kind of pink frothy effect (?too much allumina)
>3 In the firing that worked best I had smoke from the kiln
>4 I have just started using an oxyprobe and in the last firing which
>produced no red on almost everything at all except the protected half of a
>test plate the reduction used was intense - almost "off the scale" but no
>smoke. Also the flame from the peep hole was 4"long and green!!!!!!!!!!
>
>Ok this is my hypothesis.
>Far from having insufficient reduction I have too much on the firings which
>dont work.
>The smoky firing was good because smoke means poor reduction - burning isnt
>good enough even to produce CO.
>
>So, Was I literally burning off copper into the flame last time? Could one
>burn it all out and is that why some firings don't prooduce reds? Or am I
>barking up the wrong tree.
>
>Doubtless red experts will sigh and say here we go again but please, be
>indulgent,
>
>Chess
>Ammateur trying to be scientific sort of.
>
--
Mike Bailey
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