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Dawn

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My favorite Raku glaze has a finish much like a cone 10 glaze.  High gloss, even and without crackle.  In fact, I have left my work in the kiln to cool without a reduction chamber.  However, the reduction chamber creates iridecent and copper flashes as well as white "flames" in the glaze that are amazing.

 

It needs to be plenty thick to turn plum.  Brownish if thin.

 

Wild Plum

Gersley Borate or Colemanite  75

Nepheline Syenite                 25

Tin Oxide                            4

Copper Carb                        1

 

 



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Dawn Atkin
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Reply with quote  #2 
Hi Dawn,
I just tried the Plum raku recipe you have with the delicious photo..
I fired it to about 1750 and heavily reduced it.  I'll let another test cool in the kiln in the last fring of the day.
It is a pale green crackle over all...did I make it way too thick?
Ideas?
Thanks, Jane
Dawn

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Reply with quote  #3 
Yes, this recipe is green to pale blue clear crackle when the firing is not right.  At least you know the recipe is correct.

Plum does work better hotter.  We always put all the Plum in the last firing of the day and ran it to 1800 to 1850 depending on which incorrect analog pyrometer we were using.  Boy we are spoiled by digital pyrometers these days.  I believe this came to 100 degrees hotter than the normal raku firing on our pyrometors, so try 1850 first.   

Reduction is, of course, the key to turning copper green to red but the reduction must be at the right temperature.  Apparently this glaze needs it right at the end up in the 1800s.

Let us know if it works!

Dawn

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Dawn Atkin
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Reply with quote  #4 
Hi Dawn,
Ok, heres todays' run at it.
The icky brown was fired too low (my pyrometer is an embarrasment..)
The second tile was fired almost high enough all over (I guess)..and reduced
The pot was fired as high as that tile and left in the kiln to cool.
The copper red was on the flame side.
Can you get all over purples and browns by leaving it in the kiln?
How did I get copper red without reduction?
Is your photo of one that is reduced or just left to cool?

Thanks, Jane 

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Dawn

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2006 Past President
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Reply with quote  #5 

The vase in my photo was placed in a garbage can reduction with enough strips of newspaper to go half way up the vase.  The can was closed for about 15 minutes then quick cooled with a hose.  I am sorry I dont know what clay I used. 

Your red and blue tile is on the right track.  The whole point of this glaze is variations.  I have never seen the bubbling at the edge of the red like your tile shows.  Best guess - the firing was a little too hot.  Could also be a thinkness issue.  It does not appear on your other pieces, so I think it is just an odd glitch.

You asked how your vase got the copper red spot w/o reduction.  This glaze should get reduction while in the kiln, not just in the redux chamber afterward.  You will get less blue if you put the kiln into reduction after about 1650 degrees.  Of course where the pot is over the flame there is a reduction atmosphere right there - thus the red spot. 

Looks great.  I love the crane design on the tile.  -Dawn

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Dawn Atkin
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