Tumbleweed Pottery Posted May 31, 2019 Report Share Posted May 31, 2019 I'm looking for some clay bodies that are DARK. I have an idea in mind, and I'd like to have a clay as dark as something like cassius basaltic clay. But I've seen that it's SO finicky, and a lot of people have their glazes crater on that clay. I would like to achieve this kind of contrast between my clay and glaze: Sorry for the blur. Does anyone know of a reliable, tested clay body that is dark chocolate or near black, and fires to cone 6? *I know these clays can sometimes contain high levels of manganese. Does this render the piece non-food safe? Link to comment Share on other sites More sharing options...
liambesaw Posted May 31, 2019 Report Share Posted May 31, 2019 Dark bodies have lots of iron disulphide in them, or lots of black stain in them, each have their issues. My clay bodies fire a dark maroon, which is good, but also have issues with glazes that don't heal well as carbon and sulphur burn out. Link to comment Share on other sites More sharing options...
Tumbleweed Pottery Posted May 31, 2019 Author Report Share Posted May 31, 2019 13 minutes ago, liambesaw said: Dark bodies have lots of iron disulphide in them, or lots of black stain in them, each have their issues. My clay bodies fire a dark maroon, which is good, but also have issues with glazes that don't heal well as carbon and sulphur burn out. Sounds like the best way to figure things out is to buy a 25lb bag, and fire a few test tiles with my intended glaze? Then if that works well, move to a small vessel? Link to comment Share on other sites More sharing options...
GEP Posted May 31, 2019 Report Share Posted May 31, 2019 Standard 266 looks like that, but it has bloating issues if you overfire it just a little. Better to fire it to cone 5. It can also react with glazes in unexpected ways, so testing is required with all new glazing schemes. Link to comment Share on other sites More sharing options...
liambesaw Posted May 31, 2019 Report Share Posted May 31, 2019 27 minutes ago, Tumbleweed Pottery said: Sounds like the best way to figure things out is to buy a 25lb bag, and fire a few test tiles with my intended glaze? Then if that works well, move to a small vessel? Absolutely! And definitely slow bisque it. I love the look of iron clay bodies though, so I try to adjust my glaze recipes to have a less viscous melt in hopes the holes will heal over. Either that or just let the glaze have defects. I'm gonna be trying out some porcelains tonight and see if I can throw/handle/like them as much as I do the dark bodies, we will see Link to comment Share on other sites More sharing options...
Joseph Fireborn Posted May 31, 2019 Report Share Posted May 31, 2019 https://www.sio-2.com/us/language_changed/subfamily/93 This clay will do exactly what you want but is very expensive and problematic to throw well. *shrugs* Maybe other's don't have a problem throwing it, but I for the life of me cannot get a pot higher than 12 inches with it, and I can throw all of the "difficult" porcelains just fine. I have never had black ice bloat, and I have fired it all the way to cone 7, and I also have single fired it with no bisque. The clay is remarkable, and I don't know how they get the dark body, but it doesn't change the color of the glazes on top at all. Here is a cup with the clay as a slip, which is how I use the clay as I prefer to use it as a slip on my work because of the texture I get using it. (plus its cheaper to use as a slip since I don't have to use nearly as much clay to get the look I am after. The black area is the unglazed area with black ice. This is cone 6. Link to comment Share on other sites More sharing options...
neilestrick Posted May 31, 2019 Report Share Posted May 31, 2019 Standard 266 is a wonderful body to work with. Don't go past cone 5, though, and test your glazes first like GEP said. Link to comment Share on other sites More sharing options...
PotterPutter Posted May 31, 2019 Report Share Posted May 31, 2019 Agree with the others who recommend Standard 266. It's a dream to work with. I fire to cone 5 with a 10 or 15 minute hold and it is perfect every time. Link to comment Share on other sites More sharing options...
NancyAmores Posted June 3, 2019 Report Share Posted June 3, 2019 Kentucky Mudworks Brown Bear is available in a 25# sample bag. I love this clay, along with all of their clays it's just really well made. Easy to form, low absorbency, most glazes look great, particularly whites and other light colors. Edit to add Laguna's WC-391/B3 is another alternative, you may be able to find a nearby supplier to save on shipping costs. It has more manganese (4% I believe) and so is slightly darker than the BB. It's also a nice clay, but be sure to have a good vent setup, my self-rigged updraft fan wasn't sufficient so I had to stop using it after 2 time because of the strong smell. Beautiful clay, though. Link to comment Share on other sites More sharing options...
Babs Posted June 3, 2019 Report Share Posted June 3, 2019 well could solve prob by applying a black matte to lower third of pot.... like my mugs in "interesting results" in Studio forum:-/ black glaze could be more matte and black by tweaking..... just saying. Or a black underglaze.. Link to comment Share on other sites More sharing options...
HarleyDP Posted June 19, 2019 Report Share Posted June 19, 2019 Standard 710 is the same as 266 but with added grog - I fire it to a hot cone 6 without any bloating on thinly thrown mugs/bowls. It's a really nice clay to throw with! It does react strangely with some glazes so testing is key of course. Link to comment Share on other sites More sharing options...
neilestrick Posted June 20, 2019 Report Share Posted June 20, 2019 11 hours ago, harleydp said: Standard 710 is the same as 266 but with added grog - I fire it to a hot cone 6 without any bloating on thinly thrown mugs/bowls. It's a really nice clay to throw with! It does react strangely with some glazes so testing is key of course. Grog will bump up the peak temp. Is it a coarse grog or fine? I could see 266 being really nice with fine grog. Also, is the grog visible in the fired clay? Link to comment Share on other sites More sharing options...
HarleyDP Posted June 20, 2019 Report Share Posted June 20, 2019 14 hours ago, neilestrick said: Grog will bump up the peak temp. Is it a coarse grog or fine? I could see 266 being really nice with fine grog. Also, is the grog visible in the fired clay? It is a fine grog and yes, it's visible in the fired clay. This is from Standard's website about 710: "Gives a reduction-like dark brown color in an electric kiln. Smooth and plastic. Contains manganese and a small amount of fine grog is added. It's good for all techniques. We recommend firing to cone 5." Here is a bowl I did with 710 leaving the rim and foot unglazed (KY Mudworks Everglade glaze and Amaco Temmoku for the stripe) Link to comment Share on other sites More sharing options...
Michael D Posted January 8, 2020 Report Share Posted January 8, 2020 Hello All, I love that bowl you made, Harley DP. Anyone have any experience finding a clear glaze that works on the 710 without pinholing and blistering? I ran a bunch of test tiles, C6, and none of my clear glazes came out well. Maybe I have to apply then paper thin to remove the blistering... Please, any advice. On 6/20/2019 at 2:54 PM, harleydp said: It is a fine grog and yes, it's visible in the fired clay. This is from Standard's website about 710: "Gives a reduction-like dark brown color in an electric kiln. Smooth and plastic. Contains manganese and a small amount of fine grog is added. It's good for all techniques. We recommend firing to cone 5." Here is a bowl I did with 710 leaving the rim and foot unglazed (KY Mudworks Everglade glaze and Amaco Temmoku for the stripe) Link to comment Share on other sites More sharing options...
Hulk Posted January 8, 2020 Report Share Posted January 8, 2020 Hi Michael, Clear that's working for me on red clay (Aardvark SRF) - clears the microbubbles - does fairly well on Aardvark Clay Cassius Basaltic, fwiw. Last glaze firing included a set of Basaltic test tiles and a small bowl. The other clear glazes either scabbed up or retained a froth of micro bubbles. The glaze is "Wollastonite Clear" https://community.ceramicartsdaily.org/topic/20620-does-anyone-recognize-the-source-of-this-glaze-recipe/ It didn't come out perfectly smoothed over on the bowl, which may be due to thickish walls; the test tile smoothed over nicely. Solid cone 5, dropped 100F and held for fifty minutes, then free fall cool. Link to comment Share on other sites More sharing options...
neilestrick Posted January 8, 2020 Report Share Posted January 8, 2020 @Michael D Try a slower bisque, especially the last 200 degrees. You may want to drop it down to 60F/hr to make sure you're getting everything burned out. Link to comment Share on other sites More sharing options...
Michael D Posted January 8, 2020 Report Share Posted January 8, 2020 29 minutes ago, neilestrick said: @Michael D Try a slower bisque, especially the last 200 degrees. You may want to drop it down to 60F/hr to make sure you're getting everything burned out. Thanks Neil! Will do. I also think that I was hasty in mixing my first test glazes, not sieving enough, and brushing them on too thickly, The glazes all looked great on a white body, but on the dark 710 (which I love) they look horrible. (Which makes me think it has something to do with escaping gases from the body) Michael Link to comment Share on other sites More sharing options...
Michael D Posted January 8, 2020 Report Share Posted January 8, 2020 Also, (sorry to hijack this thread). My daughter made her first mugs (dark clay) and wanted to gift them to friends back at college. She is leaving soon and I don't want to rush it and ruin them. But I also need to have them finished by this weekend. If I fire a clear glaze on them and the glaze comes our with too many bubbles (making it opaque), is all lost? Can I fire it again and, say, soak longer, to clear the bubbles? I'm planning on brushing on the glaze very thinly this time. And slow firing it to C6 with a soak at the peak, and short soak coming down. Michael Link to comment Share on other sites More sharing options...
Min Posted January 8, 2020 Report Share Posted January 8, 2020 24 minutes ago, Michael D said: She is leaving soon and I don't want to rush it and ruin them. But I also need to have them finished by this weekend. If I fire a clear glaze on them and the glaze comes our with too many bubbles (making it opaque), is all lost? Can I fire it again and, say, soak longer, to clear the bubbles? I wouldn't count on it working. Are you adding brushing medium to these glaze recipes? It's difficult to brush on dipping glazes evenly without it. Link to comment Share on other sites More sharing options...
neilestrick Posted January 8, 2020 Report Share Posted January 8, 2020 30 minutes ago, Michael D said: Also, (sorry to hijack this thread). My daughter made her first mugs (dark clay) and wanted to gift them to friends back at college. She is leaving soon and I don't want to rush it and ruin them. But I also need to have them finished by this weekend. If I fire a clear glaze on them and the glaze comes our with too many bubbles (making it opaque), is all lost? Can I fire it again and, say, soak longer, to clear the bubbles? I'm planning on brushing on the glaze very thinly this time. And slow firing it to C6 with a soak at the peak, and short soak coming down. Michael Bubbles may or may not get better with refiring. Sometimes they get worse! A thin application should help in this case, though. Link to comment Share on other sites More sharing options...
Hulk Posted January 8, 2020 Report Share Posted January 8, 2020 "...Try a slower bisque..." Aye! I've been following Nerd's bisque fire advice, particularly slowing down through 752F, 1063F, and 1500F Detailed article: https://community.ceramicartsdaily.org/topic/17903-critical-firing-temperatures/ Compilation of links: https://community.ceramicartsdaily.org/topic/20132-slow-bisque-kiln-help/ Tony Hansen's article: https://digitalfire.com/4sight/glossary/glossary_glaze_bubbles.html Link to comment Share on other sites More sharing options...
liambesaw Posted January 8, 2020 Report Share Posted January 8, 2020 Slower bisque with plenty of oxygen. Use a venting system or fire with peeps out. I gave up on clears over red clay unless I'm spraying a very fine coat Link to comment Share on other sites More sharing options...
Min Posted January 8, 2020 Report Share Posted January 8, 2020 If there is a bit of iron in the clear it helps clear the bubbles. Liner glaze on red clay pot below, zero bubbles, nice and perfectly clear. I fiddled the recipe to fit this low COE clay but it started out as this one. I don't know if just adding some very fine iron to an existing clear would have the same effect. If you try this the amount of iron in the recipe I used is approx 3.5% (from the Alberta Slip). Link to comment Share on other sites More sharing options...
Marian Lake Posted January 9, 2020 Report Share Posted January 9, 2020 That's the first time I've seen a red clay look red with a clear over it, @Min Every time I've tried a clear, I had the same muddy, cloudy color after firing b/c of the bubbles. Will try your version with Alberta Slip, thanks! Link to comment Share on other sites More sharing options...
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