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maryO

Raku - Reducing A Copper Matte Glaze

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Ok, the topic re: ideal bisque for raku was so helpful as I am loading my kiln right now & firing as usual to ^04...

So my question for discussion is..."Is there an exact way to reduce a copper matte glaze?" I'm firing the glaze to ^06. Do we put it in an airtight container w/combustibles and leave it alone to cool? Do we "burp" after a few minutes? Do we throw in more combustibles to re-ignite? Do we quench w/a hose? I'm using a "tweaked" Piepenburg Patina glaze. My pieces are large-ish box shapes with about 3/8" to 1/4" walls. I've done all of the above but have had excellent results & mediocre results. I'd really like to know what works for you...

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I use a lot of copper matt. My plaques don't fit into garbage cans . I put them face down on straw and cover that with a 40" diameter steel (?) feed container I got in Mexico..actually got 2. I put newspaper on top so the back gets reduced and then place this metal container over the whole thing.

When doing this in minus 20 degree temperatures in Montana, I got the best color. I do not water the pieces down until they are almost cool, then I wash them. I have tried "burping" but I have not noticed much difference in the final results. I fire to 1850 on my pyrometer...matts don't get shiney wet to fire by eye. I bisque to ^04 or 05.

Marcia

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I use a lot of copper matt. My plaques don't fit into garbage cans . I put them face down on straw and cover that with a 40" diameter steel (?) feed container I got in Mexico..actually got 2. I put newspaper on top so the back gets reduced and then place this metal container over the whole thing.

When doing this in minus 20 degree temperatures in Montana, I got the best color. I do not water the pieces down until they are almost cool, then I wash them. I have tried "burping" but I have not noticed much difference in the final results. I fire to 1850 on my pyrometer...matts don't get shiney wet to fire by eye. I bisque to ^04 or 05.

Marcia

 

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Thanks Marcia! I'll be raku-ing tomorrow & using my usual technique...fire to 1850F, put in metal can w/plenty of shredded paper, seal, leave alone to cool down...seems like everyone has their own magic & it gets confusing.

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Thanks Marcia! I'll be raku-ing tomorrow & using my usual technique...fire to 1850F, put in metal can w/plenty of shredded paper, seal, leave alone to cool down...seems like everyone has their own magic & it gets confusing.

 

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Hi there, we do a lot of Raku in Aus. Last week we had a mixture of results with copper lustre, the ones that worked well had lots of sawdust put on them in the reduction bins for about 20mins then hosed.

The ones with only newspaper on them turned out turquoise instead of copper red. Hope this helps. Lyn

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I have used newspaper and gotten copper reds. Could it be that those pieces didn't get into the reduction as quickly as those that went into sawdust?

I don't think the combustion material is the cause of the turquoise rather than copper red. Maybe there wasn't enough paper?

I guess I need to understand the situation.

Marcia

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Instead of newspaper ( ink = nasty fumes) try getting end rolls from printers, usually fairly cheap and no ink! Same beautiful reduction. Regarding different materials for reduction , I found no difference between paper and sawdust, straw and other organtics can give a lighter reduction.

Try to pull the copper pieces out of the kiln first and get them into reduction barrels fast. You should be successful, as long as you don't quinsy the pieces you can throw them back in the kiln and fire them up and reduce again.

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After reading the above, i am thinking that perhaps 'Lyn from Aus' might be talking about a turquoise glaze not a copper matt glaze? As we all know a turquiose glaze has the potential to turn to a lovely shiny copper lustre when a good reduction is achieved.? Two differant types of glazes. Just been doing that the last couple of weeks and decided that my reduction bins are perhaps too big for my pieces and that smaller bins (to suit individual pieces) would help in achieving a better result, as i get a great reduction on the side that is laid in the bin and not so good on the 'up' side. Love Raku! Jan from Aus.

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