Saturday, June 26, 2010
When I started figuring out the stack, I discovered two things: One, I had placed a soda port too close longitudinally to the flue, such that the stack will block it; and two, the Fourth Law of Kiln Building, which states: However many cinder blocks you have, you need two more.
I finished my efforts last night in time to attend a reception at the Center for Maine Craft, a preview of the plates that will be featured at Watershed's Salad Days gala. (That's coming up July 10th -- hope to see you there!) I love those events for more than just free wine: I learn so much talking to other potters. Last night I came home with two helpful kiln-building ideas:
1) I could probably get away with building the arch out of superduty soft brick, despite conventional wisdom that the interior of a soda kiln must be entirely lined with hard brick. It is certainly true that the lower half of the walls take almost all the abuse; has anybody out there had any experience with this? I'd love to use IFB instead of hard brick, for the obvious reason of its (much) greater insulating qualities, but also because it's cheaper and easier to work with.
2) A potter whom I greatly respect mentioned that he had heard of people glazing the interior of their soda kilns, either with a very stiff glaze like a shino, or perhaps with a wollastonite glaze. He wasn't ready to vouch for this technique, not having tried it, but I am quite intrigued by it. It appeals to me on an aesthetic level -- remember, I am enamoured of kilns as beautiful objects -- and also because it seems like one of those ideas that is so obvious that you wonder why it isn't standard practice. I can't think why it wouldn't work. However, there is a world of difference between "Lori can't think of a reason" and "There is no reason" so again, I'd be delighted to hear from anyone who has seen this done.
It's a gallery-sitting day for me. so I won't make any progress today, except the mental work of figuring out my soda port problem. But do me a solid: poll your potter friends and let me know if anyone has tried either of the ideas I mentioned, and how it worked out. You can comment here or email me at email@example.com with any news. It takes a village!
Sunday, June 20, 2010
The header row is a row of straights. Get it? Header-row? Hetero? Come on! That was funny. Oh. Heard it?
Anyway. The hricks in the header run perpendictular to the line of the wall, to tie the two walls together and thereby strengthen them. One should really place a header every fifth row, but because there were some many cuts, seams, and related goofiness on the rows containing the various ports, I wanted at least one solid row before the header, or it can't do its good work. In my case, because this will be a soda kiln when it grows up, everything on the hot face must be hard brick, so excepting the corners, the entire header is hard.
Reaching the header is a kind of milestone, and depending on the weather, I am inclined to take the day off and do some gardening; my other passion for which I have had precious little time. The next post might be of the see-what's-blooming variety.
Friday, June 18, 2010
It's starting to look like a kiln! Tomorrow I will finish the layer above the burners, which contains the burner lintels, and two soda ports. After that it is smooth sailing until it's time to build the arch; at which point I have another anxiety attack scheduled. The burner ports and the flue all look gigantic to me, but they are appropriately sized according to Olsen, and anyway it's easy enough to make a port smaller if need be.
Some mistakes I could have made, and didn't:
- I almost forgot to leave a space between the cinderblocks under the stack to accommodate the propane pipe. Fortunately I noticed before I started building the stack, so it was no problem to correct.
- All of the ports need to be surrounded by hard brick, not IFB. The soft brick I am using is only rated to 2300°, because it is cheaper, and more than sufficient for the exterior. However, the burner ports are going to exceed that temp. What I almost forgot was that the soda ports need to be hard brick also, because a) soda deteriorates IFB, and b) sliding a bit of angle iron, or even the nozzle of a sprayer, into a port at cone 9 is an excellent way to get a bunch of little pieces of grit stuck to the pots.
While I was at INFAB purchasing the extra long brick to make the lintels over the flue, I asked the nice man to chop one of my own 3-inch brick in half. I didn't even have to play the cleavage card! (Just kidding. That card is a bit tattered these days.) He agreed so readily that I wondered if I should have asked him to cut a few of them; but that would have been pushing my luck.
So anyway, tomorrow I will be cutting hard brick with my trusty chisel. Only a few...but that's a few too many. It's supposed to be 87° out, so I might take the afternoon off and head down to the river for a swim.
Thursday, June 17, 2010
I hate Lewiston. Sorry, all you Lewistonians, but it's true. All of the streets in Lewiston are one way. Worse, they are all one way in the same direction..
Okay, so that's not literally true, but sometimes it seems that way. I headed off for Lewiston Refractories this morning thinking I knew where I was going. I hadn't been there in a few years, but I knew once I got to the general area, I could find it. HA!
It wasn't where I thought it would be. It wasn't a little further along than I thought. It wasn't the next street over in any direction, and nobody in the neighborhood ever heard of it. But I didn't imagine it; I still have some inswool I bought there in 2006. I remembered that they changed their name to INFAB, and searched a little more.
Finally I gave up and went into the offices of Oxford Networks, an internet service provider, and asked the receptionist to google it for me. Ha-ha, funny joke, they'd moved! I'd been driving around Lewiston in the traffic and pouring rain for almost an hour and I wasn't even on the right end of town.
When I did find them, it turns out they don't sell 3" brick. Is that really such a weird size? The fellow there told me I couldn't get it anywhere in New England, they had to special order it out of Maryland. Which they weren't inclined to do for eight soaps, and a couple of stretchers.
So now I am back home, figuring out a new plan. Sincce I don't want to dirve to Maryland, and I have plenty of 2 1/2 IFB. I think I am going to buy the additional hard brick I need and build the burner port/ flue layers of 2 1/2 inch brick. I was going to have to buy more hard brick for the stack anyway. The goofiness factor just went up a notch, but hey, there are no kiln police, right? As long as it works, I don't care if it looks like it was built by the cast of Ringling Brothers. I am off to re-do my brick count.
Of course, this all means I will have to return to Lewiston tomorrow, and I hate Lewiston. It'll be a little better now that I really do know where I am going.
Saturday, June 12, 2010
The Tenth Rule of Kiln Building States: No matter what, you will end up half-assing something. (The Sixth Rule of Kiln Building is "Have the right equipment." I haven't yet formulated the others, although they are there in my brain, swimming around, disarticulate.) Is it bad if my half-assery begins before the burnerport layer?
Despite all my careful measuring, levelling and squaring, the first layer, all soft brick, is a half-inch wider in both directions than my second layer. This only matters on the corners, where the angle iron will need to come all the way down past the top edge of the cinder block in order to accomodate a tie rod which will run below the stack. At least, I think that is the only place it will matter, so I nipped off the end of the corner brick Cutting soft brick is a breeze with a coping saw. Cutting hardbrick is a different story, requiring lots of patience and a good chisel, or else an expensive chop saw. (Of the tree, I possess only the chisel.) In fact I re-laid the hardbrick floor layer when I was halfway done, to avoid having to cut hard brick. Undoubtedly I will have to do ti at some point, but I'm not going to do it when it can be easily avoided. It's not what I would call recreational.
Each layer seems to require me to stop and cogitate for a while before moving on to the next. In theory that should prevent re-dos like the aforementioned; in practice I think some re-dos are inevitable. Maybe that is the 11th rule of kiln building.
Thursday, June 10, 2010
I woke in the middle of the night on Monday thinking, t-square. I spent all that time laboriously levelling the cinderblocks and soft bricks on the top plane but forgot to square the sides. Stupid stupid stupid; but not as stupid as getting ten rows up and noticing that the kiln is askew.
So I went and bought a t-square, which I am dying to use, but it's raining again. I'm not made of sugar (sweet as I may be) but even under the shelter, kilnbuilding in the rain is no fun; and it is supposed to clear up later.
So I am doing something else in the meantime. While demonstrating contrasting inlaid clay for my Monday night class, I had a flashback to a millefiori technique I used to teach to summer camp kids, back when I taught at the Bloomington Art Center, in Minnesota. (Hi Sue! Miss you!) I am exploring this technique a little more this morning, and if I haven't said so already, this is why I love teaching: it pushes me to try new things, and remember and change up old things.
I start with two short coils of contrasting clay, and flatten them out. Brush a little (a very little) vinegar on one surface, and then lay one on top of the other. The bottom one will be the outer color of your millefiori slices. Starting on one short end, roll the two up into a spiral; then roll the spiral like a coil to make it wider and narrower.
At this point you can cut slices from the cane, with a flexible metal rib not a fettling knife (thinner blade, less distortion.) I like my canes square, so I tap and paddle the bi-colored coils square before I cut them.
You can use the resulting spiral slices in many ways; for the dessert plate above, I lay the slices on a 1/4 slab, and then gently rolled in both directions. I didn't flatten them out completely, but left the appliques just a hair higher than the surface of the slab.
Sunday, June 6, 2010
I was able to build the entire first layer -- soft brick to protect the cinder blocks -- out of salvaged brick. Sweet! I got all the way to the last course before I had cut a brick. I took it as as my sign to take a break, since my coping saw needs a blade. Doug and I took a walk to the hardware store, which happens to be across the street from our neighborhood pub...you can see where this story is going. Doug likes to order oddball drinks, that small town bartenders won't see often; this young lady was easily stumped by a Vodka Gimlet. Anyway we are done kiln building for the day. Tomorrow it's back to the IPTOG, so I won't make any progress until Thursday. Maybe Wednesday night, if the weather cooperates.
It's not a technical, kiln building tip, but I do want to suggest: if you, like me, suffer from anxiety when faced with a challenge, try writing it out! I experinced a paralyzing anxiety from the moment I ordered the brick (notice how few blog posts in March, April, and May) until I wrote out my fears. Now I can't wait to build! If it doesn't reach temperature, well, hell -- I'll keep adjusting it until it does! If need be, I'll tear it down and rebuld it! But that won't happen. I've got Fred Olsen (and a few other knowledgable friends) on my side. This is gonna be good.
I'm very level-headed. At least, I am now! Last night I dreamed of that mysterious, Kryptonite-green liquid, and of capricious, hard-to-please sliding bubbles.
I don't know if I am being more persnickity than is strictly necessary, but I do know that there is no fix for not-persnickity-enough. Though "half-assed" could be my middle name, in this case, I am making sure it's done right.
A couple of things:
- The sand I got, called paving sand, was actually a little too coarse for the second layer. Once I started using shreds of inswool, things got easier. Silica shot or fine grog might be better. Don't use it to level the first layer, though: 80 pounds of silica shot would be an unnecessary expense.
- The second layer was at least a million times easier than the first. Which makes sense, as I was laying the second layer on top of a foundattion which had already been levelled.
- Because the whole kiln is dependent on the sand underneath to keep it level, we needed to channel water from a nearby downspout away from the kiln pad, which lay just slightly down grade from the stream. Doug solved the problem for now by digging a channel leading away. Probably I will have to do something (not sure what yet -- half-pipes? Do they sell those?) to make that a permanent feature.
Saturday, June 5, 2010
Okay, scrambled eggs and refired beans (not a typo; that's what I call them) under my belt, a third cup of coffee, and though the rain has diminished, it's still pretty steady. I am off to Home Depot to buy angle iron: either one piece, 6 ft long, to do the levelling, or all four, since I will need them for the kiln's exo-skeleton. Do they sell angle iron at Home Depot? Hmmm...well, if they don't I'll let you know. You know what I miss? Fleet Farm. As the name implies, it is actually a farm supply store, but, excepting refractories, you can get anything you need for kiln building at Fleet Farm. If you live in Minnesota. Which I don't, anymore.
Okay, I got the angle iron...but it doesn't look right. Angle iron is supposed to be blackish and look like it was forged by Vulcan himself, as primal as clay. This is metrosexual angle iron, bringing to mind skyscrapers and briefcases. In fact this isn't iron at all; it's steel.
Geez louise, what does it matter? I'm only using it today to level the sand. Anyway steel is stonger, right? That's why they invented steel. Superman is called the Man of Steel, not the Man of Iron. Silver is a nice color. I'll get used to it.
It is a measure of my inexperience that something like this is throwing me into a minor tizzy. Anyway I don't have to decide today. Later I'll call Paul Dresang, who taught me everything I know about kiln building. HA! Maybe I will have a word with him about that, too. Seriously, though, Paul will know the answer and be kind enough not to laugh at the question.
Two pieces of not-necessarily intuitive information, leftover from the plumbing removal:
- No end of propane pipe can be left open without a either baso valve or a cap, regardless of how many simple valves are between the tank and the open end. The propane company will throw a legitimate hissy fit, and perhaps even pull your service.
- DO NOT use a rubber cap for a propane pipe. Propane as it emerges from the tank, where it is liquid, is so cold that, should it ever touch the rubber, it will freeze and likely crack it, rendering it useless. I got a metal cap. I got the wrong size at first, because I meansured the exterior dimension of the pipe. Pipe sizes are described by the internal diameter. Fine Mess Pottery: We fuck up, so you don't have to!
80 pounds of sand. WIll it be enough? Hard tellin', not knowin', as we say in Maine.
And the answer is, "Yes!" 80 pounds of sand looks like about the right abount to level an approximately 4' x 4' kiln. It does make me wonder, though: What is to stop the sand from slowly washing away, over years? I should think of a way to protect against that. Othe people don't use as much sand, I think, because they probably start with more level concrete pads.
And now for the slow process of levelling the blocks. They beed to be levelled both the long way and the short way, individually and relative to each other. This is looking to take longer than I expected, so I am publishing now, against the possibility that this will take all day, and I won't feel like typing anymore, when I am done.
Wednesday, June 2, 2010
I often walk around in my life with the feeling that other people know something about living that I don't. Like, maybe there was an instruction manual, and my kit just didn't come with it. I always feel like I am just bluffing my way through, vastly relieved that so far no one has noticed that I am not, in fact, a grown-up at all.
I might buy that most people feel this way, more or less, but some clearly don't. I have a friend who, some 3o years ago, bought a shell of an old farmhouse, with no plumbing, wiring, or insulation. He proceeded to install all of those things himself, despite having no education in such matters. He just assumed he could do it, and then he did it.
I particularly envy people who have that kind of confidence about kiln building. My old kiln is demolished, and we took apart the plumbing today, and I have the brick, so there are really no obstacles to construction. Still I linger over The Kiln Book, hoping one more review will cause me to understand such passages as:
The K factor is a measure of orifice efficiency, based upon its shape and approach angles against a frictionless orifice. This efficiency has a value from 0.4 to 1.3. The best atmospheric burners have a value or 0.8 to 0.85
Actually typing it out seemed to have a salutatory effect of my comprehension. Perhaps instead of reading it, I should be copying it over!
Anyway sometimes naming my anxiety decreases it; and tomorrow I must decide the placement of the burners & ports, an necessary step after which I can begin placing and levelling the cinder blocks upon which the kiln will rest. Then come two layers of brick, and then the walls. I will begin by pretending to assume that I can do this thing, and then I will do it.