thiamant Posted April 14, 2021 Report Share Posted April 14, 2021 Is it easier to convert a cone 6 glaze to cone 10 than doing the opposite? I don't have mid range clay bodies available in my country (let alone porcelain), but I have a couple SiC glazes I would like to try. What do you think? Link to comment Share on other sites More sharing options...
Bill Kielb Posted April 14, 2021 Report Share Posted April 14, 2021 Cone 10 is a thing because that is where the earths geology melts. So all glazes really sort of start as cone 10 and we have found ways to make them melt at cone 6. We make things melt earlier by having less alumina and silica, more fluxes, some special flux combinations, often zinc and one of the most popular - the addition of boron. So most glazes in my mind start as cone 10 and we use techniques to get them to melt at cone 6 or lower. With that in mind, I think it’s easier to go from cone 6 to cone 10 but also would add you should be able to go on Glazy.org and find plenty of cone 10 recipes to try. Are there simple ways to know if something will fire to cone 6 and or 10 just by looking at the formula? Not really, many cone 6 glazes will make it to cone 10. If it has boron in it, it’s likely not needed to get it to melt at cone 10. As far as lowering silica and alumina, neph sy is one that has low silica and alumina amounts, so often cone 6 glazes will rely on it. That’s not to say neph sy will not go to cone 10 though but it is an easier material to get to melt at cone 6. Glaze calc software can help, but I don’t believe there are any that predict when something melts fully. Testing is the only way to confirm a glazes melting range. Having said that a cookie or way to catch an over melted glaze is always prudent when testing. SIC can be a difficult material to work with at any cone so careful with each test. Link to comment Share on other sites More sharing options...
thiamant Posted April 14, 2021 Author Report Share Posted April 14, 2021 Ok, what about using a cone10R glaze and adding very small amounts of SiC and see? I've seen celadons adding also zinc oxide in combination with the SiC, but I don't know the reasons behind that Link to comment Share on other sites More sharing options...
Bill Kielb Posted April 14, 2021 Report Share Posted April 14, 2021 25 minutes ago, thiamant said: Ok, what about using a cone10R glaze and adding very small amounts of SiC and see? I've seen celadons adding also zinc oxide in combination with the SiC, but I don't know the reasons behind that Maybe .......... in reduction you are looking for a way to set up favorable conditions for something to gain electrons, hence reduction reaction. If you are firing cone 10 with fuel then carbon monoxide is your friend and only a handful of oxides are affected anyway so learning how to achieve and hold a level of reduction is the challenge. If you are firing cone 10 in an electric kiln, it will be very hard on the kiln elements decreasing their life to 25% or less than cone 6 so I suspect you will not do that for long. SIC can potentially get you local reduction, but defining exactly what you are trying to do to what materials will be important to figuring out likely successful tests. It’s not necessarily a cone 10 thing actually. So if I understand correctly you are seeking reduction effects on certain oxides and your plan is SIC regardless of temperature. Again, not bad to search Glazy for similar results at the cone you want to fire. If you are using SIC to make a volcano glaze, then search for that as well. Each will require learning some chemistry of what you intend to happen which will be a good thing. Not necessarily a cone 10 thing though so converting cone 6 to cone 10 maybe not as relevant as you originally thought. maybe Post exactly what you are trying to do here (especially with respect to reduction, including color, oxides, etc...) and see if someone has a recipe that is tried and true. Often learning from the research of others saves a bunch of time learning. Link to comment Share on other sites More sharing options...
thiamant Posted April 14, 2021 Author Report Share Posted April 14, 2021 Ok. So to be more specific I wanted to achieve a celadon using some base with 1% or less RIO and also copper red in cone10 ox. With respect to celadon Im not sure if the effort is worth because maybe I could achieve a similar glaze using copper. What do you think? Some examples Cone 9-10 celadon https://glazy.org/recipes/101633 Cone 6 celadon https://glazy.org/recipes/92879 Cone 6 ZnO / SiC biaxial https://glazy.org/recipes/90751 Link to comment Share on other sites More sharing options...
Bill Kielb Posted April 14, 2021 Report Share Posted April 14, 2021 The copper red part will require reduction or use of different oxides to mimic copper red. Post a picture of your desired result here with the desire to fire cone 10 oxidation if that is still the case as well as the celadon look you are trying to achieve. You will likely get some great suggestions. It’s fairly hard for folks to comment or speculate without a picture Link to comment Share on other sites More sharing options...
thiamant Posted April 14, 2021 Author Report Share Posted April 14, 2021 Ok. Will upload some pictures when I get back home. Thank you! Link to comment Share on other sites More sharing options...
thiamant Posted April 14, 2021 Author Report Share Posted April 14, 2021 Ok with respect to blue celadons being able to get something like this in oxidation would be great. https://glazy.org/recipes/2895 I have a celadon recipe around for cone 9 that has 4% zinc oxide in it. I think i will try to add 0.2% sic to that and see what happens... So for copper red this id great but its a cone 6 recipe: https://www.instagram.com/p/CDL9jhdjf_y/?igshid=1b7vaseb6zqk8 Im still looking for good cone 6 clay bodies in my country so if someone from spain or in the EU can help me find one, I would consider changing... Link to comment Share on other sites More sharing options...
Min Posted April 14, 2021 Report Share Posted April 14, 2021 1 hour ago, thiamant said: Ok with respect to blue celadons being able to get something like this in oxidation would be great. https://glazy.org/recipes/2895 A clear base plus a ceramic stain will get you something similar, electric or reduction. Same for a green celadon or some bases work with a tiny bit of copper carb. Excellent article by Tom Turner on electric fired SiC Copper Reds here. Link to comment Share on other sites More sharing options...
thiamant Posted April 14, 2021 Author Report Share Posted April 14, 2021 I don't really like ceramic stains because (at least where I live) most of the time they don't tell you what's in them, and sometimes there's lead or Cadmium/selenium in those... Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted April 15, 2021 Report Share Posted April 15, 2021 One thing that hasn’t come up yet is if you want that icy shade of blue, you’ll need to use a porcelain or a porcelain slip over stoneware, or use some other colourant like a stain. Celadons are sensitive to changes in clay, both in the recipes, and in regards to the clay they’re on. If you put them on stoneware, you’ll get a more Koryo Dynasty green colour because the iron and titanium affect the colour. Link to comment Share on other sites More sharing options...
neilestrick Posted April 15, 2021 Report Share Posted April 15, 2021 Stains require some knowledge of how they behave in different base glazes, just like oxides. They will color shift in some glazes, but not in others. Mason, for instance, has charts that show what is required in a base glaze in order for their stains to work. That blue would be simple to achieve with a turquoise stain. Chrome/tin reds are very nice, but do not have the same look as a copper red because they are formed differently. For the two glazes you're shown, you should be able to find something close to what you need already in the cone you want. Link to comment Share on other sites More sharing options...
thiamant Posted April 15, 2021 Author Report Share Posted April 15, 2021 5 hours ago, Callie Beller Diesel said: One thing that hasn’t come up yet is if you want that icy shade of blue, you’ll need to use a porcelain or a porcelain slip over stoneware, or use some other colourant like a stain. Celadons are sensitive to changes in clay, both in the recipes, and in regards to the clay they’re on. If you put them on stoneware, you’ll get a more Koryo Dynasty green colour because the iron and titanium affect the colour. Yes. The intention is to use porcelain to show that nice subtle color the best possible way. According to some findings on glazy.org, using very small amounts of SiC for local reduction, plus adding ZnO seems to reduce the carbon trapping effect. I have a celadon recipe that contains 4% ZnO. So I will try adding SiC to that and see... I will post the results since I think not so many people have tried sic celadons at cone 9-10 Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted April 15, 2021 Report Share Posted April 15, 2021 The celadon recipe with the zinc likely has the zinc for crystal formation. In the notes for that recipe on Glazy, the author seemed to be very excited about those micro crystals. I’m super curious about cone 9-10 SiC. Do let us know how it turns out! Link to comment Share on other sites More sharing options...
PeterH Posted April 15, 2021 Report Share Posted April 15, 2021 18 minutes ago, Callie Beller Diesel said: The celadon recipe with the zinc likely has the zinc for crystal formation. In the notes for that recipe on Glazy, the author seemed to be very excited about those micro crystals. I’m super curious about cone 9-10 SiC. Do let us know how it turns out! Which reminded me of an early paper on local reduction. (ref in https://community.ceramicartsdaily.org/profile/34897-peterh/ ) One of the most interesting ideas was the use of a SiC containing under-glaze (or IIRC body) which then influenced the colour of a SiC-free glaze applied over the bisqued piece. - They give under-glaze/glaze combinations for copper reds at cones 012 and cone 9. - They suggested that silicon carbide achieves reduction-effects over this remarkably wide range by only reacting when in contacted with liquid glaze. I haven't seen this idea mentioned elsewhere (and would be very interested in pointers). Link to comment Share on other sites More sharing options...
thiamant Posted April 24, 2021 Author Report Share Posted April 24, 2021 On 4/15/2021 at 5:04 PM, Callie Beller Diesel said: The celadon recipe with the zinc likely has the zinc for crystal formation. In the notes for that recipe on Glazy, the author seemed to be very excited about those micro crystals. I’m super curious about cone 9-10 SiC. Do let us know how it turns out! Here is the result. Just about 0.02% is enough. I guess the micro bubbles are unavoidable when using SiC. Link to comment Share on other sites More sharing options...
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