Downtime

I would do the happy dance, but I am too tired. The kiln is done! Well, sort of. The door blocks are cast, and it will take them a few weeks (!) to dry, and then they will need to be fired ever-so-slowly; but as far as work, there is nothing left for me to do. That feels really weird. I keep thinking I should be doing something, but there's no work to be done.

Sure, I could tweak a few things. The stack could be a foot higher, and it could use an angle iron frame; but those aren't things that really need doing before the first bisque.

I will be posting an entry about the process of casting the blocks soon. That was the only part for which I had never even been present when someone else was doing it, during my prior kiln-building experiences, so I was flying blind but I think I got it sorted out okay. (We'll see. If I didn't, I'll show you that, too.) And thanks to a site called Lulu, I am publishing a book about this project. But mostly I will be spending the three-week drying time making pots to fill this kiln. Not today, though. Today I am gallery-sitting, and resting on my laurels. Laurels decay rapidly, but they sure are comfy while they last.

Cheers! Thanks for tagging along.

Plumb Straight

It's hard to see what's going on in this photo, so I will clarify: I tacked a string with a small weight (a "plummet") tied to the end from the rafter of the roof over the kiln. The purpose is to make sure that the stack goes up straight, as over 30-plus courses of brick, a slight list can turn into a giant, unstable one. As you can see, the 2 courses above the standard come in slightly; fortunately we hung the plumb line before it got any taller. Such simple technology; but nothing better has yet been invented. 

Though the exact function it was made for is unknown, the little stone being used as the plummet has a small groove carved around the narrow end, making it perfect to tie a string around.  That groove was carved over 3000 years ago. The rock was found on the Sebastacook River, a remnant of the people who lived there before Europeans came to this contintent. We've already brought this item to the attention of the archaologist at the Maine State Museum. who deemed it authentic but not particularly unique or interesting, which is why we still have it; but it pleases me to use it to plumb my stack, and imagine somebody millenia ago used it to make straight lines as well. 

A Few More Notes About Castable

Sorry. Castable is my boom! It won't last. 

I started to apply the insulating layer to the arch today. I decided to mix and apply it one five-gallon bucket at at time, because bashing up soft brick is killing my neck and back, and I just can't do all that I need without interruption. 

I started out intending for the crushed softbrick particles to be about the size of coarse grog, but quickly settled for a gravel-sized bits instead, when I saw how dreary and, eventually, painful the task of crushing brick was going to be. 

They only sell Portland Cement in 94-lb bags. 94 pounds!! Come on. While there are lots of people who can easily lift 94 pounds, there are lots more who can't. I can lift 94 pounds, but, ya know -- I don't want to. I'm going to grunt, and stumble, and possibly lose my grip on the bag, and have to heave it to get it in place, and my back will hurt the next day. Whoever decided that 94 pounds is the optimal package weight in which to sell portland cement was obviously not thinking of women, but not just that -- there are lots of men who would have trouble, too. The entire lot was only $9, which I suppose is great if you need lots and lots of it, but really, who needs that much? I mean, besides almost everybody who buys portland cement. But what about all those -- I don't know -- hobby masons? They must get stuck with loads of extra cement. Me, I would have gladly paid $9 for 40 pounds of it, which I can easily lift. And now I am going to have to figure out what to do with the leftover. Which is going to mean lifting most of it, as I only need a few pounds.

Oh, and I am sure you already know this, but portland cement and concrete (which is conveniently sold in bags weighing as little as 25 pounds) are not the same thing. Concrete has little rocks and other crap in it, which we don't want, as we are going to add our own little rocks and other crap in the form of crushed brick and Hawthorn Bond. Cement is also not to be confused with plaster of paris, but that is a story for another day. 

Anyway. I mixed up a five-gallon bucket using parts-by-volume, 12 pts crushed brick, 7 pts Hawthorn Bond, I pt Portland Cement, 2 pts water. I applied it with a trowel to the west side of the arch, and will finish tomorrow. I certianly hope I am doing this right, as it is a sort of leap of faith -- if I've got it wrong, I'll probably eff up the work I've been doing for months now.

Either way, I'll let you know.

And Now a Word about Castables

Warning: this entry will likely be hideously boring to non-potters. My apologies. Sometimes I note things here so I know where to find them!

Several words, actually. Turns out to be a more complicated subject than I thought, and very little information is available on the web about castables. It's worth noting that two of the three potters I consulted recommended commercial castable, specifically mizzou, if it is to be used for anything structural, like, say, casting the arch itself. I was able to score four (or four and a half, depending on how you look at it) recipes for insulating castable, such as you would use to put over a brick arch, to slow heat loss. I was quite surprised by how widely differing the recipes are.

Tim Cichocki, a potter from Norrgidgewock, Maine, used this recipe to insulate his groundhog kiln:

Equal parts:

• Fireclay
  
• Sawdust
• Silica Sand
• Portland Cement

From Tyler Gulden, Executive Director of the Watershed Center for Ceramic Arts:

• 12 parts crushed soft brick
• 7 parts fireclay (Hawthorn Bond)
• 1 part Portland Cement

Tyler also offered a more durable, less insulating version:

• 10 parts crushed soft brick
• 9 parts fireclay
• 1 part Portland Cement

From Reeder Fahnestock, Watershed's Facilities Director:

By weight

• 4 parts Fireclay
• 2 parts Alumina
• 1 part sand or grog
• 1 part crushed soft brick
• 1 part Portland Cement

I found two castable recipes on the web from Goshen College in Indiana. This page contains a very thorough treatment of the subject, and more complicated than my needs require, what with all the laminating of the hot-face and insulating mixes. For my door, I am only casting hot-face blocks, and using soft brick outside them. The recipe that I need for this purpose is:

Door Brick Castable Recipe for Soda: Non-Insulating

• 10 parts Kyanite
• 1 part Ball Clay
• 2 parts Fireclay
• 3 parts Kaolin
• P-grog (a high heat duty grog, sold by AP green)

I will be applying the insulating castable directly to the exterior of the arch, so of course there is no way to fire it; therefore Portland Cement is useful is persuading it to set. Portland Cement melts at ^10, however, so I decided to steer clear of any hot-face recipe that contains it. ( I know, I know -- lots of highfire claybodies contain material that fluxes at ^10, it all depends on the proportion, blah, blah, blah. I guess I just don't trust it. Plaster has never been my friend in the studio.) I am leaning towards the recipe which is heaviest on the crushed firebrick, for my insulating layer, mostly because I have  a whole boatload of rubble softbrick, and it seems a shame to waste it. I just have to pulverize it. 

Applying castable will also be a learning experience for me. Specifically I am wondering how long it will stay workable. Should I rent a small concrete mixer to keep it from setting? Or mix up small batches, only as much as I can apply before the set time. What is the set time, anyway?

If you have the answers to these or any of life's persistent questions, shoot me an email at castable@finemesspottery.com , or reply in the comments.

It takes a village to raise a kiln. 

Boom Boom: Out Comes the Form

Burn it out? Or slide it out? Burn it? Or slide it? Burn or slide? These are the things I spend my hours wondering. How best to remove the arch form, now that the brick are in place. 

Burning is more fun by miles, but sliding is more practical, as someday I will need to rebuild the arch, and when that day comes, it would be nice to still have the form. So I'm sliding, if I can. It will still be necessary to burn out the frame holding up the form, so I get a little of both. Here goes!

Past the first ring of brick, which required a bolster in one place, but held...

Uh-oh. Damn that quarter-inch plywood! Damn my cheapskate nature.So, the form will not survive anyway, which means Plan B is activated: Burn that baby out!

I had meant to take photos while the form was burning out, but as it happened I didn't care to set down my trusty hose once the blaze began. The spaces in front and behind the arch forn were still unbricked, so the flame was not entirely contained. A couple of notes: 

• If you live in town, as I do, inform the fire department and your neighbors what is going on. There is going to be a world o' smoke. 
• We've had a crazy dry summer, so I hosed off evrything near the kiln, including the beams of the roof over it. The tongue of flame jetting out of the front opening would have licked the shed roof five feet above it if I had not been there  damping it back with the hose.
• I only burned enough to remove the actual  arch form. The support that was holding it at the proper height is  (obvs) very charred, but I will remove it by hand, becuase of the whole out-of-control smoke and flame thing. 
• A half-brick that had not even seemed loose when I was building dropped precipitously when I slid the form forward. I propped it up until the brick around it could sink the fraction of an inch I knew would occur when the form was no longer holding them up. Once the other brick sank and pressed against it, my woould-be dropsy brick was pinned in place. 

Next on the to-do list: castable. 

2 x 2 x 2

Arch construction is easier with two: 2 people; a 2 x 4; and a 2-pound sledge. Here's Doug tapping in a brick for a nice snug fit.

I was frustrated (so what's new?) because the charts in the Olsen book did not include a combination of brick for my span, which was 31". I know that is a weird span, and it ought to be 31 1/2", as brick are 9" long, but remember I had those weird-ass bricks. I had a little flexibility in the span, but the closest width on the chart was 33".That seemed like too much to fudge, as it would create turbulence in the flame, and with it inefficiency and probably a hot spot.

But I used the numbers suggested for the 33" span as a starting point to purchase arch brick, and then stood them in a ring on end to discover what combination of what brick got me closest to 31", without going under.  This worked out quite well, although, as it turned out, once I placed them on the form, I hat to switch out a row of arches for another row of straights, because they were much tighter with gravity pulling them together. 

I do have two "loose teeth;" Possible solutions include custom-cutting (or grinding) a hardbrick; stuffing the gap with a tiny sliver of softbrick, which I would glaze (shino) on the bottom; or..well, I guess those are the only options. I might try both: the sliver of softbrick up front where it will be (relatively) easy to replace if anything goes wrong, and a custom-cut brick in the back. 

I have the week of Labor Day off from the IPTOG, during which I hope to complete construction at long last. My to-do list looks like this:

1.  Repair 'loose teeth"
2. Build form to cast door blocks
3. Mix up hot face castable and strike the blocks
4. A trip to INFAB, probably in a rented truck, to get the necessary brick for the stack
5. Mix up and apply insulating castable on top of the arch
6. Build the stack. 

Wow, it looks more daunting all written out like that; but on the other hand it is an observably finite list, as opposed to the nebulous "all that stuff" label I had been applying to my remainig tasks. 

I should have cast the door blocks first, as waiting for them to dry will push off the first firing by as much as two weeks. Guess I should move them to the top of my list. 

Think good thougths for me, that Maine doesn't get clobbered by Hurricane Earl, and also that this week stays out of the nineties. Brick dust stuck to sweat is itchy. 

Arguing Eggheads

These s & P shakers will be in the first bisque, tentatively scheduled for September 5th, and then in the first soda firing, Sept. 10, unloading the 12th.

Problem Solved!

Since the Great Welder Meltdown that happened Independence Day Weekend, I have been dithering about how to get the welding done. Well: not just dithering. The plumbing; the stack; the arch form; I worked around the problem for as long as I could, and tried to work up my courage to call Augusta Tool Rental. Everyone kept telling me welding was easy, I'd be able to figure it out no problem. Still, I was intimidated, so I put it off and put it off. 

Last week a friend of ours was visiting, an elderly gentleman of Ivy League background. I showed him the progress I had made on the kiln and explained the obstacle: welding the frame. I told him I was thinking of just renting the equipment and figuring it out myself, at which he shook his head: "No, no, my dear. That's for the other folks."

"The other folks, Bob?"
"Yes, the ones who do that type of thing."

There was no use explaining to Bob that I have always endeavored to be one of those other folks, the ones who know how to do things, and anyway I realized that as wrong-headed and snobbish as the comment sounds, he was right in an essential point: there are people for whom 16 two-inch welds of iron bits would be nothing, no more difficult than throwing a board of mugs is for me. I knew welders existed, of course, but that was when the lightbulb went on that it makes no sense to struggle and dither when I could just get it done, in an hour. It's okay to have help.

Arch Nemesis

I so wish I had a camera! The arch form is complete, and it is such aa appealing object, itself.

I had one false start, when I decided I was very very clever and would avoid the tedious assemblage of slats by using a length of flexible hardboard bent over the form. Yeah, don't do that. The board is not THAT flexible, and tacking it down was almost impossible -- it kept pulling nails loose, and the flat sides weren't flat. Oh, for my camera! The result would have been funny instead of murderously frustrating if I had known I could share it.

Anyway the form is complete. Hopefully I will be able to get some shots of it before its duty is done.

Canoeing today, if the rain stops!

How Things Stack Up!

Obstacles, obligations, and temperatures in the nineties conspired to make July a bust for kiln-building. No lie, the entire month was inchwise. And our camera went bye-bye, so you'll have to take my word  that it's August now and I am back on track. On the downside, I am bailing on a family vacation (well, half of it) to get there. I feel like a bugturd about it, but I was just so frustrated with everything taking priority: work, family, classes, vet appointments, gallery-sitting, everything.  All important stuff, to be sure, and most of it not optional, but at some point I had to declare that the kiln is important, too; otherwise it just won't happen. (See: Housepainting, three-quarters finished. )

Technically I got back on track yesterday, the very last day of July. I started building the stack finally, and while there is, predictably, some half-assery going on, I made good progress. Is it a bad thing if my tolerance for half-assery rises geometrically as this project wears on? I've reached the damper, for which I need a lintel brick that I don't have (natch), so I am going to build the arch form today, instead, and head to INFAB tomorrow. I need some more arch brick anyway. 

I was surprised to discover that INFAB doesn't sell skewbacks, so my choices are 3: have them shipped from Sheffield, MA (although, surely, now that I think on it, there must be another supplier of refractories closer than that: I can't believe that no one in the entire Boston metro needs kiln brick); make them out of castable (cheap and doable, but one more step in a project with too many steps already); or have INFAB cut them out of straights. So I guess I've got some phone calls to make, about pricing. I only need about 8, so how much can it be? 

Anyway. It looks cool and dry today, a perfect day to build an arch form. Feeling only slightly guilty, I will wave my family goodbye and get moving!

Quick Kiln Updates

1)Like so many things, plumbing turns out to be not half the big deal I thought it was going to be, It helps that Home Depot will cut and thread pipe for you, at a ridiculously small price. (I did have an amusing incident at the register, when the cashier accidentally rung up my 37 inches of pipe as 37 feet. She was a little huffy and said the tag was written wrong, but really, does this look like 37 feet of pipe?) Any case the plumbing is ready to go. If I'd known it was so easy (and so cheap!) I might have repositioned the two burners that remained as they were in the old configuration, but what I've got will work just fine. Just storing it away in my Big Book o' Lessons.

2)We had to fire our free welder, for repeatedly (and persistently, after several requests to stop) making racist and homophobic remarks. You think you know someone...Anyway. That sucked, but some things are more important than kiln building. (Not too many, but some.) We have another friend who can help if we get ahold of him; if not, I do know a professional I can hire. Welding is not a task I'd try to learn on the fly. I am kicking myself for not learning to weld during either my undergraduate or graduate programs, when the metals sculpture studio was right next door. (I wasn't too interested in the metals, although I remember having an interest in one or two of the sculptors...)

Salad days at Watershed today! Hopefully photos tomorrow. 

Get it Right the Second Time

I had to tear down one wall of the kiln this week, due to a 'clever" design change I made to the flue. I'm not sure what inspired me to re-work my original flue design, but I suspect that it was a desire to avoid having to manually cut soaps (lengthwise halves) from 3-inch brick. The second design looked like this:
I built all the way to the top layer of straights before I realized the problem. As you can see, if you follow the vertical line of the edge of the flue upwards, it butts right against the soda ports. Which means the soda ports will be hidden behind the stack wall. Nice going there, Ace! I spent a day trying to figure out how to rework the stack or the ports before I decided that was too much power to give to a mistake: better to correct my error than compound it.

So Thursday I took the back wall down, built the flue as I should have in the first place, soap-cuts and all. By this time I am an old hand at cutting hardbrick with a chisel, and though it was slow going it wasn't really difficult. 

Lessons learned: 1) Don't make design changes on the fly; and 2) the difficulty I am trying to avoid might not be the big deal I think it is.