Claymonk's Journal

Three years ago, when I first started this blog, I wrote about using a BBQ smoker for pit firing, because I did not want to draw unwanted attention from nosy neighbors and fire marshals. As those of you who live in modern big cities would know, we often have all kinds of fire ordinances and burn bans to contend with, and striving for a look of innocently doing what every other urbanite or suburbanite would be doing is an important ruse for self preservation, if one is to succeed in pit firing in the city (or suburb) in the long run.

Unfortunately these BBQs didn’t work out all that well, as they were not designed for the prolonged high heat generated by a log burning fire. My BBQ smoker, for example, has paint on it that would start to burn after a while, and would give out noxious fumes and visible black smoke. Talking about trying not to draw attention! So I gave up this approach after just a few times.

Then I started to see these stand-alone outdoor ‘fire pits’ made of metal or clay at the patio furnishings section of department stores. Would these work for my purposes? After all, they were designed to burn logs, no? So I bought a cast-iron one (figure 1) from Home Depot and start to experiment with it. I did my first firing with it at the end of April this year.

Initially, I worried a little that, since the bottom of this ‘pit’ thing doesn’t touch the ground, the firing may cool too fast, resulting in incomplete color development, or worse, in cracking and breakage. Well, it so happens that my fears were unfounded. The pieces turned out just fine — see figure 2 beblow: a group shot from the second firing, just after the pieces were removed from the pit, before any cleaning or waxing. Oh the first firing was good too, but I didn’t have a group shot like this to show you. :-(

So now I have a little test pit to try out different fuming methods and effects, and to ask questions that I’ve been itching to have answers for, e.g. can I get away with not using any copper carbonate at all? How about using no copper of any kind, not even the copper nettings (e.g. from a “Choreboy” type copper scrubber), just steelwool and salted grasses? Or no copper, no steelwool, and just the salted stuff? Or how about using copper and steelwool, but no salt at all? Or…

Do you want to know the answers, too? Stay tuned. As it turned out, I have done many of the experiments already — I have done 10 firings in this test pit so far — and will show you some of the results shortly in an upcoming post.

Meanwhile, here is another picture of a nice piece from this firing ( figure 3 below) after it has been cleaned and waxed.

And below is the other side of the same piece (figure 4). Notice the inscription on the piece — which says “HC0812-23″. Okay, here is what this is all about. “HC” is my initials, “08″ is for the year 2008, and “12″ for the month of December, and “23″ means this is the 23rd piece made in the month of December 2008.

Someone once asked me whether this is an On Kawara kind of thing. Well, no, actually it isn’t. Not at a conscious level anyway.

For me this is simply a unique identifier — a serial number, if you will — for the piece, that comes in handy in conjunction with meticulous note taking, which I usually do. Here, for example, I can look up my studio notebook and see that this “HC0812-23″ piece was made with OH6, a white porcelaneous stoneware clay from The Clay Art Center, that it has two coats of OM4-based terra sig, and that it has been bisque fired to cone 012.

Also, from my firing notebook, I can see that this piece was packed with my standard three amigos of steelwool, copper netting (”Choreboy”), and salted raffia, and that it was placed in the first layer (directly nestled in sawdust) at the north end of the pit.

In the photo below (figure 5) is another piece from the same firing. Again, from its unique identifier, HC0812-35, I can find out that it, too, has two coats of OM4-based terra sig, that it was bisqued to cone 012, that it was placed in the first layer in the pit (at the south end), and that it was packed with the same three amigos of steelwool, copper netting, and salted raffia. The claybody, though, is a commercial buff-color stoneware called Idaho Buff, also from The Clay Art Center — and not the porcelaneous, B-Mix type OH6 used in the previous piece.

Below is yet another view (figure 6) of the same piece.

“Aha!” — I can almost hear some of you exclaim now — “I see these nice maroon red areas in the OH6 piece, but none here. So white porcelaneous clay gives you these reds, and the buff clay doesn’t, yes?”

Well, no, not so fast please, my friend.

Remember, we have precise documentation on clay body, surface treatment, bisque temperature, etc. because these information can be easily recorded and documented. In a typical pit firing, however, there are a lot of other information, some of which are far more critical than what we have here, that are nearly impossible to record with any degree of certainty and specificity.

A prime example is the flame pattern. How much flame action did each piece get to see? For how long each time, and at what stage of the firing did this happen?

Another is the firing atmosphere local to the piece in question. How early did the piece become exposed, and thus had its fuming materials burn in an oxidizing atmosphere? Did it then get buried by embers and ashes again, and thus entered a reduction phase locally? And when did this happen? And did the ashes burn down eventually and re-expose the piece again before everything cooled down?

While impossible to document precisely, such information can be gleaned in a general way, via written notes in conjunction with photos and videos taken during the firing; and they provide important clues to interpret the results of the firing. I’ll have more to say about this in a future post.

This entry was posted on Sunday, October 18th, 2009 at 12:43 pm and is filed under Pit Fired Pottery. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.