Kelly in AK

I have to jump on the train and say that not only will it be easier to find video references for what you want to learn, but they’ll probably give you more information faster. You can use your experience to interpret what you see: How soft does the clay look? How are different sizes of pots approached? What is the relationship between work done on the clay and work to keep the wheel moving, and does it change as the piece progresses? I like to read more than I like watching videos, but some things are easier to apprehend seen than read about.

You can glaze them, it may be a challenge.Warm the pots, spray the glaze. Thin layers with, ample time to dry between coats.

It’s not for food. Liquitex matte medium, a room temperature finish, may fit the bill. It’s UV protectant. Produces a satin finish. Reliable and long lasting. Your fired pieces should be archival without that though.

My reflex response was “iron, cobalt, and manganese together.” @Min covered it, so I just want to second that. The commentary on the Vince Pitelka recipe on Glazy is as valuable as the recipe itself.

Yes, no problem in a bisque firing. And, yes, wadding is fine on porcelain.

I appreciate this conversation, I had similar issues since getting a Peter Pugger (VPM20) a couple years ago. After using it I learned how it’s different than every other pug mill I’ve used. Had trouble maintaining a vacuum at first, tried all sorts of gyrations including sealing with clay. That all went away, it works without thinking about it now…magically. I’m still trying to get every ounce of perfectly mixed de-aired clay with the least amount of effort though. This thread helps.

Mark, you may be slowing down but the production, even in “retirement mode,” blows my mind. I don’t know many potters, because in some corner of my mind it’s a title. You are a Potter. Rare breed, I think. Along with others, I’m grateful you share your experience and expertise.

It’s just conjecture on my part, maybe someone will chime in with other ideas or experience, but my mind goes to more calcined clay in the slip for less shrinkage wet to dry, and perhaps cmc gum to make it harder it once it’s dried. Rhodes crackle slip (various versions on Glazy) doesn’t produce the extreme texture you’re looking for, but it’s a step in that direction. Applied to bisque ware.

Something like this reminds me a bit of Robert Sperry, along with some really gnarly shinos in historical Japanese pottery. Granted, they’re two different things. I was told many years ago Sperry used slip on top of glaze for his dramatic effects, I can only imagine it was the product of serious experimentation. I’m afraid that’s all I can offer. https://www.bellevuearts.org/exhibitions/past/robert-sperry

What a delight to hear more about the lives of people I interact with regularly but don’t really know at all. I’m an art teacher at a public school (22+ years). It’s unusual in that it’s a k-12 school. I have to explore all sorts of creative endeavors just to be good at my job. A few of them drew me in far beyond what I needed to teach the subject. Clay is where my heart is, I got a BFA and MFA in ceramics before my teacher life. A significant part of “extracurricular” creative activity still revolves around it. I like to make the tools I use and I want them to be as beautiful as my pots. The wood for handles and ribs comes from what I collect and I will use a branch or plank or block I harvested over lumber from the store at every turn. The students got me into paper making, poor things didn’t know I was going to make them chop apart plants, boil them in alkali, then spend hours beating them to a literal pulp. I’ve made a lot of paper of my own since then. Coptic stitched a few journals too, @GEP. A serious creative anomaly happened when I decided it shouldn’t be so hard to distill essential oils from plants. I was wrong, but the process relies on third world technology and I’m pretty fluent in that. A couple years later I had an efficiently working still and system and obtained essential oils from the most interesting plants growing locally. When I learn about something I get more interested in it. It’s a blessing, and a curse. I’m always up to something.

Stands for Question of the Week Hyn Patty, and this one sounds great.

I have used gold and silver lusters in Raku firing on burnished clay. The more polished it was, the better. Lame on bare clay. The most dazzling effects came from spraying them with ferric chloride right after pulling them from the kiln. I was a bit bold in my younger days. Ferric chloride can produce its own luster on polished light colored clay/white terra sig. As the pots cool applying more tends to look like smooth rust. Where it interacted with the commercial lusters was strongly metallic, iridescent, and variable. It was a special firing, somewhere between cone 018-016, very low. Only skin deep, but very compelling. The clay body was white as a bone. 30 years ago.

I feel obliged to say that nearly everyone who has programmed more than a handful of firings has done this. Once. Welcome to the club!

Don’t place your cones too far from the peephole, they’ll get lost in the glow (advice). IR glasses were a great move for your long term eye health as well as to see through all the radiant energy. I might put cone 7 in the sitter, then babysit the kiln till witness cone 6 goes down, shut off the kiln, then figure out how to adjust the sitter. I often have a misplaced sense of economy, so that’s not advice, more like a confession.

Ramblings follow. The pots I value most sell the best. Price, style, glaze, size, and type, seem less relevant. Bowls, mugs, and cups may seem to break this pattern because they’re a “type,” something easily adopted into any household, and fall into a narrow price range. They sell most. But, no, my assertion holds. The bowls mugs and cups I value most sell first, even priced the same as other like items. The only magic formula I’ve found is to make pots I think are interesting and beautiful based on what holds meaning for me, and share them best by making work that’s a pleasure to hold and use and look at. Never boring and always a challenge. People are buying more than a ceramic object. They are buying an object from you. If, somehow, you are a part of that object it changes the equation. For me, if a person picks up a piece and asks one question, it’s as good as sold. Not because I’m a salesman, I’m awful at it, I just answer, we talk, and it confirms they’re looking at something from the heart, made by a human, and it’s a good thing. Rare. I tried chasing million dollar glazes and decorating fads a while and found it soul deadening. I’m not above making an object that sells like hotcakes, it’s just not my driving force. Everyone always says blue sells well. Hope that helps Betty.

To be sure, a picture is worth a thousand words. Very helpful. The clay body looks gritty. The pinholes are not like craters at all, no raised rim, not looking like bubbles that popped and didn’t heal. Every one is more like a sinkhole. Widely but evenly spaced, not concentrated in a particular area. Important diagnostic clues. I can’t say more at the moment, I just know the picture tells a lot.

Getting it double thick to the top of the kiln will certainly make a difference, I can only guess if it’ll be enough. Since you’re so close, I suspect it will be. Soft brick is better for that outer layer, yes, better insulator.

This guy is 2-1/2 pounds, so I suppose it started with around three pounds of clay. It feels about right. No “ballast” around the bottom. I have to say, I put some real effort into throwing eggshell thin for a long time, and like to do that in demos for beginners, to show them what’s possible, but better too thick than too thin is my vibe now. Balance.

Making the world a better place. Good man. I appreciate the sharing.

You’ve gotten tons of excellent advice here and provided great documentation for people to help you. My first impressions were: Beautiful kiln, you’re going to get there, just a few tweaks away. The first two are general principles, the third applies directly to your kiln, forced air or not. The firebox always has to be larger than you think, wood needs a lot of room to combust. There has to be significant space under the grate, air is what’s making the wood burn hot enough (air’s got to go under the burn, not over it). Double brick that chimney! Insulate it. At least to the height of the kiln. The higher the better. I’m not going to give you a long story, I’m just telling you in all sincerity it will change things dramatically. Air is key, and that column of air has to stay hot to create the draw needed to make wood burn at 2300.° You’re advancing along this learning curve rapidly, Olsen and Rhodes’ guidelines are excellent, but, as you may have noticed by looking at many kilns, not set in stone. The groundhog kilns of the Carolinas were my inspiration. I built a mini, and double bricking the chimney took it from cone 6 with difficulty to cone 11 with ease. 12 hours.

I don’t want to bark up the wrong tree, so I’ll ask this way: What’s changed? You’re using the same body, but is it possible the formula has been changed? The clay maker might not give you the formula, but they’ll probably volunteer whether and how it’s been changed. Have you used cones lately to verify the kiln is doing what you think it is? Which material you’re using is the newest purchase? That’s a of questions and no answer. My feeling is you’ve been riding on the cusp of this a long time. The drop and hold schedule suggests you’re already correcting for it (edit: I imagine the drop/hold and slow cool may also be to enhance mattness). Some single variable pushed it over the edge is my guess.

And here we come to it, the rub. Glazy has been a godsend to me, and I’ve yet to see anything bursting that bubble. I learned glaze chemistry and calculation thirty years ago in college, and used it loosely, only to evaluate recipes. Now, as then, I rely heavily on materials knowledge and gross ratios to come up with what I believe will work. Glazy allows me to put my guesses into a context of what has worked in other places for other people, and reduces (not eliminates) the testing. For materials that don’t have a published chemical analysis, or materials that have the same name but varying compositions (this talc vs. that talc, “ potash spar,” “boron frit,” or my local clay) there’s still guesswork. It takes much less effort to arrive at a data point that before would have been tedious to find, even with previous glaze calculation software. Glazy rests on the shoulders of everything that came before it and I don’t discount that, but we live in good times. Three cheers for Derek Au. I, like @Roberta12, look for that sweet spot on the UMF chart, nudge my glazes towards it and wait and see how the pots look after a few years in my kitchen. The only faster way to test seems to be alternating baths in strong alkali and acid (good old lye and that potent 30% vinegar @PeterH mentioned in another post). Like the weatherman, we haven’t arrived at perfect prediction, but it’s a lot better than it used to be.

The least amount of exposed skin. Long sleeves and full pants. Clothes you won’t cry about when an ember burns a hole in them. Cotton or wool, not synthetic. I mostly use ordinary leather gloves until late in the firing, when I switch to leather welders gloves with the high cuff. Comfort and dexterity are important until it gets too damn hot. Never synthetic gloves (though there are heat resistant synthetics such as Nomex, I just haven’t tried them). Leather shrinks and becomes rigid when exposed to extreme heat. Seams fail first because they’re synthetic (plastic) thread. I consider gloves a semi-consumable. I’ve used cotton jersey gloves, they’re very cheap and provide some insulation, won’t melt onto your skin, but they also wear out quickly. Don’t use any glove with a hole in it, anywhere, you will get a burn. Footwear is always closed toe, usually leather, not necessarily boots, but socks must go above the ankle. No exposed skin! There is a lot to be said for behavior over wardrobe. Tie your hair back. Never reach in, use a stick. Don’t stand in front of the firebox, stand to the side. A position five or ten inches lower can be 100° cooler.

I wasn’t reading carefully enough, and spoke before I knew what I was talking about. Sorry about that, it happens occasionally. I’ve had a concentrated share of picking up the pieces after deceased family members the past two years and my mind went straight there. I wish you (and Phil) the best of luck completing this arrangement.

This prompts me to share two microwave experiences in which pots cracked. Very different clays and experiences. The first was an earthenware bean pot I made. It had regular use on the stovetop. Always soaked in water before use, heated slowly over gas, and made the best beans. I was fastidious about cleaning it. Occasionally it grew mold. I would scrub with baking soda, fill it with water and boil for a couple hours, then rinse and dry, which kept it sanitary for a while. Once after this process I had the bright idea to put it in the microwave to dry it better, mold needs humidity. After a couple or three minutes I heard a clearly audible crack and discontinued that experiment. The pot made three or four rounds of beans after that before I decided it was ready to fall apart and tossed it. The next was trying to gauge how the microwave affected vitreous ware, mostly interested in iron content relative to heating. I tested a cup, iron rich clay, interior glazed only, for absorption. Heated in the (regular) oven at 185° to make sure the dry measurement was accurate. Two hour boil, then sat in the pot of water another four hours. Came out at less than 1%. Then I put it in the microwave (empty) to see how hot it got after two minutes. Before the time was up I heard an audible crack and stopped it. The cup was too hot to touch. It has a crack you can find if you really search for it in good light. I still use it. These are the only two times I’ve had a microwave wreck a pot. Both were empty and dry on the exterior but were also saturated, though one had below 1% absorption. No explosions.