skuzbucket

Sorry, I unloaded a little before I remembered to snap a photo. the kiln was loaded pretty much as tight as possible given the way the dome curls downward at the arch- which is a slight pain in the butt but not horrible. certainly I was able to sneak pots put tight to the arch even at the top of the front stack... so there were two distinct sections to the stack- the back half like this:

and the front half composed 2/3 of pots on shelves with those two tall pillars off to the side- the front was the portion that got the most hot- was it stacked to a similar tightness as the back?- I pretty much think so, but the nature of the spaces was totally different- lots of choppy ones instead of tall columns as it was in the back... anyway- the front was massively more hot than than the back- cone 12. the back top was at about cone 8, bottom more like six.
this is so you can see what I'm talking about with the flue openings- lots in the floor, and a lot in the wall- so for this first fire, I had all the wall closed off, and most of the floor open. it was closed only on the right side near the firebox, because I anticipated using only one side of the kiln's potential fireboxes. but that's another story.

so it is clear that simply having most of the floor openings open in the back is not enough to move the heat back there-- ok, now we know. you can see what was open in the second photo. and remember that I yanked out the bag wall, which was a triangle-shape, taller in the back of the kiln. this would have been even worse, in hindsight. Stephen Mickmaster came to the unloading and suggested a small bag wall at the opposite of where I had had it even temporarily- a little deflector triangle at the front of the kiln- I may do that yet, but I like the rest of his suggestion better- open up some ports in the wall portion of the flue- and figure out a way to slow the flame- more of a skateboard of a target brick, or a rubble by Richard's idea, and of course more focus on air to the back in terms of flue openings... What I'll probably do is load a super-dense load of pots at that place where the bag-wall should be-

But here's the current bane of my existance: SCUM!! scum started when I asked my clay company to ad 5% redart to a "takamori" blend of porcelain. I had done this in grad school without problems.. big disclaimer there- so I had no qualms about ordering half a ton of the special blend from the clay company. they mixed up 2800 lbs for me, which I should have noted to them at the time... as it happened, something about the redart is causing a migration to the surface of the soluable calcium- as the pot dries, any oils on my fingers are making - not a resist- the opposite- a magnet for a scum to form. it shows up in the firing as a thin but distinctly gray layer. flowerpots below are from this firing. color is a little wacked but unintentional surface design is evident.

Below is a pot from a previous firing at Mt Hood college- in a salt kiln, and reduce-cooled, as this one was. Neely thought that perhaps the salt was aggravating it, essentially giving a light tacky surface on which the soot would settle and integrate with the surface. (I hope I got that straight- it was over a year ago). but there was no salt in this kiln... may I draw attention to the orange flashing at the center of the frame- I sanded some of these pots before firing them, to see what would happen- that orange is the most clean clay. then there's the scum, and an inbetween zone.

one photo shows the marks from my rubber rib- there at the top of the left-hand pot is where I pulled the rib upward. lower on that cylinder is a big gray band- why there and not elsewhere? anybody??


so here's the left hook: while I was at Penland, a friend used my studio, making pots with her own porcelain. here's one of hers:


there's no glaze on that pot. there is pretty much no chance for soluable soda ash or any of those quirky elements to be responsible for that mark. turn the pot right-side up in your head- looks to me like water dripping from the lip, absorbing into the clay, like she had washed the rim (with water from my tap...!), and then trimmed it- trimming off the bottom half of the "active ingredient"-- anybody? does this make sense? clearly, the marks on her pot are not scumming but flashing. but is is possible that the minerals in my water are reacting to the redart in this batch of clay to create an unusually subtle problem?? comments, please?!
I'm going to throw with distilled water for a while and see what happens-
next firing scheduled for the end of september.

Ist firing- Aug 2, 2008

Damage assessment reveals that a mere 20 gallons of honey-gold veggie oil, not more than 1/2 cord of wood, and 33 beers were consumed during the first firing. Given how little of the first two were used, I am forced to assume that the primary fuel required for this firing was alcohol. This is not a boast. The first firing tested all manner of variables. One of them was how I lead. I was sober, of course, as was the person "on shift". beyond that, it gradually turned into a fuzzy line- there were hangers-on who made themselves useful in a time of need and we could not have done it without them... I prepared as best I could given the wide array of unknowns, but we suddenly needed a pile of side-stoke wood, and lo! it was created, without loss of finger. Later in the firing, we needed to carry on side- stoking wood, and helping hands were still there. My gratitude to all who helped in many ways... Richard, Jack, Jamie, Oliver, Tim and Travis. hats off, my dears-

The first firing was excellent. Not at all how I expected it to be, excellent in its own way. It helped enormously to spend a few hours warming up the chimney before beginning the candle. most pots were green, large, and porcelain. six hour candle, slow rise to 900*, and about 100*/hr after that. this made for about 24 hours up to 900, 12 hours to cone 04, six more to cone 12, and four in reduction cooling to 1850. There was a certain point in the evening when Timmy and I were puzzling over the correct path and Richard confirmed what was becoming a growing realization: this kiln really loves the woodfire. But he loves the oil fuel too. we found ourselves side-stoking, directly into the firebox, through a port I had imagined would be used mostly for soda, or reduce-cooling with wood. it was remarkably painless, for woodfiring.

The whole story: Here's a photo of he floor of the kiln, from the front.there is a firebox channel 9x9 in cross-section that runs continuously from the front of the kiln to the back. at one opening, we stoke wood. at the other is an oil burner. the kiln is symmetrical- there are two such channels at each side. there are vertical dampers that control the opening to each fuel source, and a space by which the channel opens into the chamber. In the center are also two parallel 9x9 channels of floor flue, making it a downdraft kiln. those channels are spanned by these huge bricks with holes in them. there is also a large opening in the wall of the chamber so that the entire floor flue area can be closed off, including the place where it enters the chimney, and the whole kiln can be fired as if a crossdraft (except it isn't really a crossdraft since the fuel sources are more like a downdraft configuration- from the back sides and exiting the back, but it might give a more crossdrafty look than not)

I think that bit about the wicking action of the bed of coals was accurate. in the pre-firing, I had managed to turn on the oil when the chamber air temp was about 600*, meaning much much lower than that at the point where the oil burner was located. of course I was hugely excited and watched the temperature soar as I turned on the air and oil together. I managed to find a setting that was about 100* an hour, a safe heat gain for the hypothetical pots. I watched it as such for about an hour before heading to bed, thinking an hour was sufficient proof that the burner worked at that temperature because of its efficiency among other things... all well and good.

BUT the coals had not fully burned off in that baby firing. I think now that if I had observed the oil burner for two hours instead, I would have seen what we saw during the real firing: as the coals burned off, the wick burned away. the sudden temperature soar was the sudden rush of air from the burner over the coals. the slow gain was the adjusted air flow but basically still the same action. without the wick of coals, the oil could not burn properly at lower temps?? something- it needs a porous craggy surface from which to burn. maybe a rubble of soft brick would work as well. but i think it's not just a wick but also a radiant heat action taking place-- what we observed, to our dismay, is that at 600*, at 1100*, at 1600* on the pyrometer ( located again, far away from the burner port,) at every point, we would switch on the oil, observe a sudden spike in temperature, a gradual tapering-off, and then a slow but inarguable decline --as the coals burned off---. at 1700* we tried yet again but by this time, night was falling, we would have kept the ladies of the house awake with any more wood splitting- (oh- yes, so up until 1700* we basically gained temperature by side-stoking wood.)--- so we stood around staring at the pyrometer like some folks stare at a television set hoping and praying that the oil would catch and stay caught. But before we dared find out that it wouldn't, we just kept on with light side-stoking while keeping the oil on.

so, to be clear, before about 1700*, we gained temp with wood, occasionally trying oil, finding it ineffective, and shutting it off, resuming wood. by 1700*, we'd pretty much realized what was going on and decided to keep up a light side-stoke for the primary purpose of maintaining a proper bed of coals into which the oil would spray. It was as if the oil was super-charging the coals, and the amount of wood required to gain temperature was minimal- 3 or 5 short sticks every few minutes for a cyclic gain in temp as woodstoking tends to show.. Oil flow to each burner was at full throttle. air passing through the blower was at about 2/3 open. we figured out a pattern that seemed effective, averaged out the heat gain at about 80* an hour including all the noodling around and failures, and calculated that we were only three hours behind an optimal schedule without mishap. at 12 am, I took a cone reading in which 1s were down, and passed out for three hours, anticipating a long and intense night. Richard closed off the last 15 square inches of passive damper and wakes me up a bit later- "um, we have good news for you- cone 12 is down almost everywhere..." -- the consistently cool spots at about 9. so Jamie and Oliver took off (thank you two ever so much!) as Richard and I sealed up the kiln and began reduce-cooling. he slept for a few hours as I continued, and the firing was complete at about 7 am monday morning.

other tidbits: 1: at a certain point mid-afternoon, we had tried the oil for the second time (1100*), and found it was smoking badly, acrid smell, as if a heavy reduction. kiln was behaving as if he were choking. I leaned a ladder against the chimney and removed the piece of expanded steel that I had installed on the suggestion of a fire marshall. it was about 3/4 blocked off with soot. I added a foot onto the chimney. I will add another foot, for a total of 14 from floor level. I've decided to do this because through out much of the firing, we pretty much had the active dampers wide open and the passives all in. I would like to have a little more elbow room than that.

2: for this firing, the "cross-draft" flue opening in the kiln was completely blocked off, and 10 of the 12 "down-draft" holes in the floor were open, primarily on the left side of the kiln, and towards the rear. this would make for 70 square inches of flue opening in a 65 cubic foot kiln, about twice what Nils Lou suggests in his book. I opted to double it for two reasons- mostly being chicken, and wanting the control of quantity of air flow to come from dampers which could be changed during the firing. but those holes in the floor intrigue me- how to move the heat more forward or back by which ones are open-- as a side-note- no bag walls in this firing. I loaded about 40 cubic feet of pots into the space, densely packed.

thoughts for the future: build an after-market bourry- box on each side of the kiln for more effective and physically comfortable wood-stoking in the beginning of the firing. a fine idea from richard. the only catch is that we need to be able to push the coals into the channel near the oil burner so that we can use them as the wick. I'm sure I can figure that out... one big question is this- what if we push coals forward at, say, 1000*, and continue to "side-stoke" above them lightly as the oil droplets soak into them. will it work? or will we need to continue with wood somehow. next time, we will find out! same bat-place, same bat-channel......

roll the drums

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Tin Man

Meet the TIN MAN....he just passed his most difficult inspection. THREE CHEERS!!!

what's happening these days is that I did indeed need to employ a third party inspector, partway because of tightening permit requirements and partway because we are a specialized bunch, us wiley potters who make their own kilns. we are a blur on the screen, electrons of questionable location. they just can't keep up.
so we passed! a slightly elder statesman named Sandy trundled into the back yard with his computer and a suitcase full of gadgets and gizmos, surprised that it wasn't running. Running! this might be a three-day process, I can't just flip a switch! but we met in the middle, me explaining the ways in which I had incorporated an afterburner, how I had designed it, and how I expected to fire it, and we looked at the burners and took them apart a bit, changed the power cords to ones compliant with UL listings which involved a little bike ride to the hardware store, and over the course of the day ended up trading all kinds of great stories about fire and boats and treasure hunting. then we let the burners run without flame for a while while he gave me a great idea for a cheap oxy meter, and told me to look into creating a reduced atmosphere by replacing some of the gas inside with nitrogen... and suggested thinning the oil with alcohol in winter. (so long as i can get a stir-stick into the tank somehow.) He was impressed with the design and construction... so I'm gloating right here.
SO! I'm going to fire it up, empty, tomorrow. Sandy doesn't buy it that the oil wouldn't ignite below cone 08, so I'm going to try. a potter friend of mine says they do it in Japan.. he says that it's only at first that the burn would be at its least efficient, and that is when it would be producing the most carbon monoxide. then we'll load on monday, tuesday, fire uh, friday, sat? I'm all involved in the Portland Open Studio tour, interviewing people and going to meetings, so there are two of those events in the middle of all this, but that's the idea...
and I still have to get 70 gallons of oil in the bed of my truck into the tank in the garden. Jack and I spent all day battling two shitty hand pumps from harbor freight- trying everything, plan f, plan t, plan x, y, and z, plan arrghh!- so I think that until my new 12V pump that I eventually forced myself to order arrives by stork, I will indeed be siphoning it out a few gallons at a time- if it will out of such a tall tank, and pouring it into a funnel. I suppose there are worse ways to spend a day. this is how people get buff without meaning to..

one ox-cart, a middle-aged horse, and a sword

I'm having engine troubles. This is my incredibly useful truck, ie ox cart, shown here transporting two barrels of honey-gold fry grease to the kiln. .....but every trip to the gasohol station costs seventy dollars now. so obviously I drive only when I need to move something other than my own little tush. thank god I live in Port-land of bike lanes and kneeling busses. if I played the oboe, even the bassoon!, I could live without any vehicle whatsoever! But how to visit Brenda or Robin, nestled with their families among the fields and fens? What of the ocean? two hours and a hundred dollars away... or, heaven forbid, I get a steady job teaching somewhere? it came down to blind passion. last summer, in a fit of crush, i bought a horse. I'd been stuffing the paltry earnings of my so-called business into a bottle for a year. my kingdom for a horse! I made the man who sold it to me break the bottle over my table to get the bills out:

he's kinda old. not a pretty boy, i mean bike. tempermental. solid.. I love him. but yes, it's a little scarey- there are still lots of suv's out there, left over from the old days... so there's the crux of the debate: we are at the tipping point- oil is not going to get cheaper. the culture of oil is dying- all the petroleum that goes into the production and transportation of beef, the availability of strawberries in january, felling trees in Canada to build homes in Houston, boiling and refining tar mixed with sand(!?) to feed our ignorant demand for everything, anything, and NOW. the suburbs will be abandoned and recycled- who can afford to drive to them? or they will become townships in themselves- an autonomous ship of a town, economy once more localized, part of a flotilla, serviced by carriers of goods whose oars might be oxen... probably segregated, but that's another story. do I digress? I was just on this fabulous road trip all around the east coast, carried aloft like a dankity queen on the sound waves reverberating off luxury speakers in a luxury car. I lived luxe, i burned a lot of fuel (and I bought a lot of pots- he he!). and I knew it would probably be the last time I had the chance to be so carefree before the hammer really fell.
so what do you do when the gavel falls? is this the story? have one last blowout and then buckle down? is buying a motorcycle a luxury of romanticized freedom or is it a transportation necessity? is it somewhere inbetween- a new paradigm for the shifting times? a new horse? or is it just dangerous and irresponsible and I ought to take my pop's suggestion and run it off a cliff (presumably I would be strapped into a hang-glider at the moment of take-off) - wasn't there a winged horse in greek mythology? Pegasus: it sprouted from the body of the gorgon (not gorgonzola) Medusa when some handsome man named Perseus cut off her head- I think the gorgons had snakes for hair and one could not look into their faces or else be turned to stone- Perseus looked into a mirror instead. how apt. we must look inside to make the changes. we must act differently.
Now I will deliberately digress: really fastinating article in the new yorker called "the itch"- did anyone read that one? the nerves that register itch are not necessarily nerves, but often memory without connnection to external stimuli. the itch is mental. same as phantom limb pain. there is memory that gets shorted out, creating physical sensation. a remarkable therapy places a mirror edge-to the body axis of a person with phantom limb pain, mirror side on the half of the body that has a full limb. then, wave the arms, conduct an orchestra in the air- look at the limb in the mirror as if it were on the other side. the memory gets a shock, a scrambling- new information, new limb, new paradigm. the train of old thinking about pain jumps a track.... me, I've been experimenting. every time I'm lonely at night and want a drink, I reach for the new yorker instead. I'm just trying to not look the gorgonzola in the face.

and what of the sword? I killed my chainsaw the other day. oh fool, how could I? put generic two-cycle oil into my fuel instead of brand-name. and not quite enough of it either... my trusty sword, smoking hot! which would be sexy if it weren't also a problem. so here is a tear-streaked eulogy to this chivalrous knight's trusty damascus. I place it in the stone: "he who so pulleth out the sword from this stone and anvil is the rightful king of all england" .. maybe I'll pull it out this winter and teach myself how to fix it. yea, right- I'll probably end up turning it into yet another useless art project: "Mechanisms of Chivalry: an mobile of Irreconcilable Ideas". hot air rises and makes smog about this. and this.

prickly pear

I decided to stay. a few factors weighed in- not so much formal obligations but more like self-perceived nebulous ones. basically, I can't stand to be quite that irresponsible. I know beauty is in the eye of the beholder and so is whether or not I am irresponsible, but since it's my life and my perception, I'll just blame my lutheran roots and carry on working...
really, no-one would have missed me at the special exhibit of woodfire work that brought together all the local characters with some international flavor, but it was great to see people that I love and like to fire with... it's an excellent community I've fallen into here- it's great to be home. that's what it comes down to- it's great to be home- I actually would much rather be here now, learning how to fire my kiln, this summer, than anywhere else in the world. grease fire in portland beats out flame trees in Fiji. my heart is here. ...not to mention that pop wouldn't have been captaining her- I'll gamble for the day that I can make such a remarkable passage with him.

And SO! I have been insulating the kiln. have I mentioned that I am in love with my kiln? god, I hope i did a good job designing it and that I don't gett shut down via some mishap with a neighbor. I'm famous for mishaps, so I'm nervous. but as much as i can comply with city code, I am, so there's little to complain about. other than the plumes of smoke that smell like fish and chips, perhaps. my landlady is amazing. and so is stephen mickey for giving me all those awesome bricks.

more free materials came my way in the form of many random scraps of insulation- so random and so valuable. I used to do thousand-piece jigsaw puzzles when I was a kid, so this was nothing. just itchy like fingers on a chalkboard. it all worked out to a solid four inches on the dome roof:

and a layer around the walls, backed by about two inches of mineral board ripped into lenghts on a slight bevel so they'd make a relatively seamless curve. chicken wire to hold it all in place:

Lady Linda has most graciously agreed to let me borrow her burners while i wait for mine, so I am in bizness!!! I am aiming for a firing in two weeks time. but there is much to do including final inspections by the city. (chief dude knows me- he saw the kiln walls but no roof)

I like Jack's comment: looks like an engineer did the front and a boy scout did the back.

much love from the great northwest-
C

prickle fish