whimsley Posted August 4, 2021 Report Share Posted August 4, 2021 I have a raku-fired copper matte reduction pot that I’m not happy with. I’d like to reglaze it and fire it to Cone 6. Do I need to bisque fire it again before reglazing and firing or can I just glaze right over the copper matte finish? I’d appreciate advice. Thanks Link to comment Share on other sites More sharing options...
Min Posted August 5, 2021 Report Share Posted August 5, 2021 Main issue with this idea is the raku glaze is a lowfire glaze and you will be firing it up to cone 6. The lowfire raku glaze is going too in all likelihood way overfire at cone 6. I know there are some lowfire glazes that are okay being fired hotter but the majority aren't, they blister and / or run etc. If you are really keen to try it I'ld try a test tile with the lowfire raku glaze on it, doesn't need to be raku fired, and put it in a little saucer of clay and fire it up to cone 6 and see what it does. If that test comes out okay then I'ld consider a very light application of your cone 6 glaze on the raku pot but would fire it on a waster slab to catch possible (probable) glaze runs. This is assuming your claybody can go to cone 6, most commercial raku bodies can. Welcome to the forum. Link to comment Share on other sites More sharing options...
neilestrick Posted August 5, 2021 Report Share Posted August 5, 2021 The other issue is that most copper matte glazes aren't good glazes- many aren't really a glaze at all but rather slightly fluxed out copper- and may not behave well with another glaze on top of it. It'll take some testing for sure, and I wouldn't trust any result to be food safe. Link to comment Share on other sites More sharing options...
Pres Posted August 5, 2021 Report Share Posted August 5, 2021 One final issue is the clay itself. Many of the raku clays fire below ^6, so you may have bloating or slumping issues. All in all, your best bet if to try a refire of raku, or to dump the idea. best, Pres Link to comment Share on other sites More sharing options...
Benzine Posted August 5, 2021 Report Share Posted August 5, 2021 @Pres The Raku clay I use is rated for Cone 10 and even beyond. I know of it even being used in wood firing. Link to comment Share on other sites More sharing options...
Pres Posted August 5, 2021 Report Share Posted August 5, 2021 I have used several different raku bodies in the earlier grad school years, Dontigny used one that fired to cone 9-10, but I had one from another teacher that was cone 4. I also used a fast fire clay body that use perlite as a filler along with saw dust, and grog. This clay was made for cone 4 max, and was H on folks hands so sandy. best, Pres Link to comment Share on other sites More sharing options...
Marcia Selsor Posted August 6, 2021 Report Share Posted August 6, 2021 I'd just refire it in raku. Maybe fire it 25-50 degrees hotter. It would not be a good idea to cover it wit a ^6 glaze. Marcia Link to comment Share on other sites More sharing options...
Benzine Posted August 6, 2021 Report Share Posted August 6, 2021 On 8/5/2021 at 4:33 PM, Pres said: I have used several different raku bodies in the earlier grad school years, Dontigny used one that fired to cone 9-10, but I had one from another teacher that was cone 4. I also used a fast fire clay body that use perlite as a filler along with saw dust, and grog. This clay was made for cone 4 max, and was H on folks hands so sandy. best, Pres Yikes, that's some "groggy" clay! I used my midfire white clay, which is rated for Cone 6, for a recent Raku workshop. I had never tried it before and was worried it might not handle the thermal shock. It did just fine. I also have a brown midfire body, that specifies that it is oxidation only. I kind of want to try it in Raku just to see what happens. Link to comment Share on other sites More sharing options...
Pres Posted August 6, 2021 Report Share Posted August 6, 2021 Perlite was used to allow overnight drying, and then raku firing, body was very open. This was at a state level PAEA conference. best, Pres Link to comment Share on other sites More sharing options...
Benzine Posted August 7, 2021 Report Share Posted August 7, 2021 18 hours ago, Pres said: Perlite was used to allow overnight drying, and then raku firing, body was very open. This was at a state level PAEA conference. best, Pres I added wood shavings to a body one time for pit firing, for the same reason. It's always nice to have a workplace, that has an industrial tech area! Link to comment Share on other sites More sharing options...
Pres Posted August 8, 2021 Report Share Posted August 8, 2021 Yeah, but there is a downside to that sometimes. My classroom in the basement in the beginning had a wood shop, and across the hall from them was the severely handicapped children. My worse time was when the shop teacher was planing a lot of cedar, and mix that with the urine a poop smells out of the spec ed room. . . . as I was down the hall from both, and the loading docks for the central supply was at the opposite end; I felt like I was living in a hamster cage! By the time I left though revenge was sweet, as the shops closed down. . . much to my chagrin and I took over the two rooms that the spec. ed had been in for my new computer animation classes. When this art teacher retired he had the most real estate of any one in the school district at the educational level. best, Pres Link to comment Share on other sites More sharing options...
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