Kelly in AK

It sounds like it’s being over fired. If it’s a low wide cone, perhaps fire it point side up with just a lump of clay underneath supporting the center. A picture might help people understand your problem better.

Just watched it with my partner in clay and in life. Movie night. We both loved it. Never had heard of Clarice Cliff. Getting to watch an inspirational feature length movie about an interesting person and geek out on clay at the same time is a rare treat. Thanks for mentioning it @Hulk!

Hi Maggie, could you let us know what clay body and glazes you’re using? That information may really help people solve your problem. Also, photos are invaluable for troubleshooting, if you can post pictures that would be great.

It does depend on whether it’s a deairing pug mill or not. If it is, then you shouldn’t have to wedge it if the clay is properly mixed. If it’s a pugger-mixer that shouldn’t be a problem, but if only a pug mill you might have to run it through a couple times. Now, if it’s not a deairing machine, then you might consider stack and slam wire wedging. Attaching a wire to my work table was such a good move, saves a lot of effort. https://ceramicartsnetwork.org/daily/article/Stack-and-Slam-Wire-Wedging-An-Efficient-and-Easy-on-the-Wrists-Way-to-Wedge-Pottery-Clay

I use something similar to dewater clay. There’s no moving these when they’re full though.

I saw a picture on the internet where someone was wondering about the chips of clay in their glazed pot. After further inquiry, this was a community kiln and it was discovered a pot blew up in the glaze firing. It’s happened to me, or to say it better, I’ve done that. Anyway, it got me thinking, “What’s the worst ceramic screw up I’ve ever made?” It’s a tricky one for me to answer. There are so many! If I had to gauge by number of pots ruined in a single go, well, I seem to do that as a matter of course with my own work. Those aren’t screw ups if they help me get the next round right. Okay, yeah, some are just plain screw ups, still an opportunity to learn from my mistakes. In my studio there’s no one to blame if something doesn’t come out right. So then I go to other people’s pots I’ve ruined. I’ve blown up a few, enough to know I didn’t want to do that anymore. I’ve disconnected a (poorly attached) handle or two when loading the kiln. Some of those incidents are shared responsibilities, so I can’t take full credit for all the disastrous things I’ve been a part of. Probably the worst is when I was learning to fire with a digital controller. I was a fresh-from-art-school tech at a community studio. They had better kilns than any I used in college. I was absolutely positive I put the numbers in right. Some how this bisque firing went awfully high. (?!) I had some earthenware pots in there, those came out great. Better than planned, clay was vitreous, the glaze was crystal clear, and fit like a glove. Completely unexpected. Everyone else’s pots, however, had become vitreous too! Cone 6 stoneware, I have no idea how hot that kiln got. I dealt with some unhappy campers that week. We learned how to glaze vitreous pots. I suspect I fired it to cone 4 rather than 04, though at the time I was convinced it was an error with the controller. Never happened again though. Now that I think about it, it’s a wonder my earthenware didn’t melt all over everyone’s stuff. Could have been much worse!

Dick, I think you’re going to like the frit! I resisted for years, not so much from cost, but because frits felt so “artificial,” and Gerstley is (was ) such a miracle material. I got over it. So totally over it. 3124 and 3134 are my trusty friends now. A little more Epsom salts, a touch of bentonite, because the magic power of Gerstley to keep things in suspension is gone. I’ve still got a couple glazes I need to recalculate myself though.

Anchorage is at the point where two giant glacial drainages meet. Our gravel pits, hence sand supply, are loaded (intercalated, geology not calendar) with silt, which is just the sand ground to such a fine mesh as to be reclassified as silt. In other places the silt is in lenses with clay and sand, which makes picking out clay tricky because they’re all the same color, made of the same stuff! So, bless our road crews, they dig up sand and spread it ‘round to keep us from crashing our cars, but the silt and clay get kicked up in spring. They’re not literally spreading silt on the roads. It’s always been a dusty paradise here, long before sanding intersections was common practice. Apparently buses here have a knack for concentrating the dust. @Russ, I have to chuckle at your reaction because that was a little bit my point. Driving a bus may be more dangerous to your lungs than having a clay studio! Mine is certainly no model of a “free silica free” environment. I’ll breathe more free silica on a windy summer day outside than through the cold months of winter plugging away in my studio. Most of us will die of something else long before silicosis is a problem. Still though, no reason to breathe more dust than you have to. I’ll confess, those final videos of Richard Batterham haunt me.

All I can say is I’ve never seen anyone say not to. I remember some discussion about how the two wear things out slightly differently, but both are so corrosive the larger issue is dealing with that. Someone said the soda residue was more hygroscopic, and freeze thaw cycles affected it more. I think that was in the context of trying to get away with building an IFB soda kiln. I’ll say this about wash- I use zircon wash on the walls and floor of my soda kiln. I feel it resists the soda better, maybe even creating a slight barrier. Alumina wash on shelves and to make wadding. Zircon fires very hard, even though it’s nowhere near melting. I made some wads with it once and those dang things were awful to get off the pots.

A friendly reminder to keep the studio clean showed up in my local news. Potters aren’t the only ones who have to worry about silicosis, apparently bus drivers in Anchorage do too: https://www.alaskasnewssource.com/2023/06/22/anchorage-fined-nearly-80000-silica-dust-exposure-municipality-buses/

To add, or perhaps say the same thing in a different way, my move is to put the words: ceramic arts daily forum in the with search term itself. For example, if I want to see what people said about spodumene I search “spodumene ceramic arts daily forum,” without actually using any quotation marks or “and,” because as Hulk said, those operators can prompt the search engine to do very specific things (at least they used to, everything has developed so fast I’m not sure what the rules are anymore!). Using just words has been working fine for me. Google, Duckduckgo, and Yahoo all present results slightly differently, but the forum posts are at the top of each search regardless.

My experience matches @Min, the more specialized my questions got in Google, the more often this forum appeared in the search results. I don’t generally do searches through the forum. I use Google or some other search engine. It seems quicker for me to go through a search engine and navigate that way, even when I’m looking for something specifically in the forum. Expressway vs. scenic route.

Veering slightly off topic, but I have a special place in my heart for Mack brushes @Hulk. My summertime alter ego is “sign painter,” no one makes a better brush for that.

Wonderful breakdown of a slice of earth, as dug. I very much appreciate comparing the photo to the analysis. So those white looking bits in the brown ball clay layer, are those shale?

Congratulations on your new kiln and welcome! If the piece feels cold against your cheek then it’s still drying. It won’t hurt to let it dry more, but you could hasten the process by candling. I fire lots of student work, just as thick as this, always candling for several hours (4-6 hours) before the kiln really starts to heat up. That will prevent explosions, getting all the water out

Looking forward to seeing how it all develops. I too am afflicted by this disorder, “good pots begin with digging good clay,” though I don’t believe it’s officially listed in the DSM (yet). I noticed the same thing: Tony Hansen and Glazy’s specs on Lincoln are different than what you’ve got. This is some special clay though, you’re fortunate to have it nearby. The proof is in the pudding, physical testing will show you more faster than any chemical analysis can, in real time, in real life. In a sense, materials analysis is just physical testing taken to an atomic level. Evaluating plasticity, shrinkage, firing deformation, and absorption are things you can do in house. Data you get from those tests are often validated by the spec sheet, but can’t be always discerned by just looking at a table of percentages unless you are a wizard. When you know enough, you could probably estimate the chemical composition of a clay by tests you can do yourself (“If this, then that, if not, then this, this, or some other thing…”). Anything Tom (@glazenerd) says about clay formulation and testing you can take to the bank. Continually thankful for his input wherever it occurs. Wizard. And Tony Hansen (Digitalfire) is some kind of saint. You will find more information, more documentation of tedious testing, more valuable analysis of clay there, freely given, than anywhere else on the internet. Glazy runs a close second. I stand by my suggestion to try a bit of “common clay,” local red earthenware, as a means to flux Lincoln to maturity at cone 6. My impression is that it won’t take much, since it already seems to vitrify around cone 8. I’m no wizard, just a fan of keeping it local. Glad to hear you raised the mixer. That move will save you a lot on physical therapy later in life!

Gonna go out on a limb here and suggest all chalkiness will disappear when you fire the clay to maturity. The sample photo many suppliers use shows it’s significantly lighter at cone 03 than cone 5 or 7. Considering most people bisque between 04-06, it may be lighter still in a regular bisque.

Sounds like you’re in a good place to get some clay someone else dug up, cleaned out, and processed for you. I wouldn’t mind that one bit! Lincoln 60 is a winner in my book. I used it as part of my clay recipe for a few years until shipping costs became prohibitive. (Mine’s very different from yours, cone 03). My first thought was to suggest blending a local red/common earthenware with Lincoln until you get the mix that vitrifies at cone 6. Tony Hansen suggests it ought to be possible by just adding feldspar (link below). https://digitalfire.com/material/lincoln+60+fireclay

Processing 150 pounds of clay. Should keep me going a little while. I’ll probably do another batch before fall.

Oh you’ve really challenged us here Preston. Now I’ve got to think of all the things I ought to be doing this summer, instead of all the clay work I could be doing now that school’s out. Thank you for bringing balance to The Force. Recent events have made me want to visit and reconnect with family, so far away. My son and I will be heading to Louisiana for a bit to do that. Then there is camping in the Alaskan wilderness. To her credit, my partner will not let me avoid it. I live in one of the most beautiful places on the planet, thankfully she prods me out of the studio enough to remember it. As always, the summer will fly by and I’ll do half the things I hope to (fix the broken parts of my house), it will be amazing, and I wouldn’t change a thing.

Ahhhh. The best solution. Find something that works and stick with it. No one can say you didn’t try, that’s for sure! I appreciate you sharing that journey.

I don’t think it’s exactly that simple, but probably not too difficult either. Glazes usually (always) have silica in them even if it’s not a separate ingredient. Clay, feldspar, and most frits contain silica, and those are major glaze ingredients. From a little searching I see that purples/violets from manganese are produced with a very small percentage (2% or less) in concert with an even smaller percentage of cobalt. Try searching for “manganese violet glaze recipe” or “manganese purple glaze recipe.” to start with and see what you find.

From browsing the web I see there is a variety of clay in all those states, Indiana seems to be the one where clay is still actively mined/processed on a large scale. https://igws.indiana.edu/IGSMap/mineralproducers The darkest blue dots on the interactive map show clay and shale producers.

I usually have resize photos, I use an online tool.

Post pictures and see if anyone can help. If you can, show the bottoms and any marks that might identify a maker. People often sign or stamp their work. Worth a shot. Fun story, I was having dinner at a colleague’s house. He’s the science teacher, I’m the art teacher. In Anchorage, Alaska. He says, “You’re into ceramics, you might recognize these bowls,” as he loads one up with salad. “They’re made by someone named Shoji Hamada.” So, he grew up in both England and Japan and his parents were great friends with Bernard Leach and Hamada. He just kept pulling out Hamada pots that his mom had given him while I was picking my jaw up off the floor. The kicker was when he pointed to a pot on his fireplace mantle and said, “That one’s a Peter Voulkos.” Sure as hell, a signed Voulkos, an early one, when still made pots that looked like pots. ”We use the pots because mom said that’s what he would have wanted. She loved pottery” You just never know.