There was a time when the only thing I was reasonably sure of about pit firing, as far as fuming effects and colors go, is that you’d get a jet black area where your pot is buried in the sawdust or horse manure. But those days are behind me now, and as I have achieved better control over the fuming effects of my pieces, I start to itch for ways to get rid of those jet black areas that are the tell-tale signs of pit firing.
There seem to be two kinds of potters out there. Some will put their best efforts in trying to make better or more beautiful objects, functional or otherwise; while others will spend at least equal amount of time — and energy — in finding out how the process really works, and treat the whole exercise of making and firing pottery almost like a branch of empirical science.
I most probably belong to this second group. Well, some might even say I had gone over the edge, that I was actually more a mad scientist than an artist — which I would gladly take as a true compliment, by the way. :-)
And here is a manifestation of this truth over beauty tendency of mine. Instead of following my own proven three amigos (steel wool, copper mesh, salted raffia) formula to make more good-looking pieces like these or these, I decided to try just one amigo at a time, and see what will happen.
I thought it was just a fluke the first time this happened. I was at a group pit fire last year where I had seven pieces out of a total of thirty some pots in all. Most of my pieces turned out beautifully, so I wasn’t too upset when I noticed that one of them did not have any colors at all — only black and various shades of gray.
Well, it must have been in a corner where we forgot to sprinkle copper carbonate; and the copper mesh and salted raffia wrapped around the piece must have gotten knocked loose by falling logs too — so I thought to myself, and promptly forgot about the whole thing.
Then I started to do a lot of firings in my little backyard pit, and much to my chagrin, these all-black or black-and-gray rocks also began to crop up a lot more frequently (figure 1 above, and figure 2 below.)
Those of you who have followed this blog for a while would know that I’ve long been looking for proofs that one doesn’t need copper carbonate, a toxic (and expensive) chemical, to achieve the kind of maroon reds and blueish grays commonly associated with copper fuming.
I came really close to showing that I can get the same effects with copper netting from “Chore Boy” type copper scrubbers; but a real proof would require not having any copper carbonate in the pit at all — which I couldn’t really do in a group firing, where other people were there to get nice results for their pots, and not to help me prove or disprove some fine point in pit firing theories.
But now I have my own test pit, and the only pots at risk are my own. Woo-hoo! So after two successful firings using my standard method, proving that this test pit works just as well as any other I’ve used before, I went for a test firing with no copper carb at all in the pit, and was very pleasantly surprised to see some very respectable looking results (figure 1) for my efforts.
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.
Well, well… it’s been over a year since my last post here. Though I did not get to fire much in the last two years, I finally managed to achieve fairly consistent results by the last couple firings. The firing method remains essentially unchanged, i.e. a fast 6-hour affair in a relatively shallow pit, details for which can be found here and here. And I still use mostly cone 6 porcelaneous clay, but now bisqued to cone 010 instead cone 06.
(Update 2009-10-25: now I typically bisque my pieces to cone 012 instead.)
What I want to write about in this post, though, is how I use fuming materials to achieve the kind of results as shown in photos above (figure 1) and below (figure 2). This approach, of course, does not work aesthetically in all situations — so I am offering this only as a hopefully useful reference. As always, take whatever you need from it and adjust to your own requirements as you see fit.
This is a video clip of a group from The Pottery School in Pioneer Square doing a pit fire at the beach in late July.
The firing was pretty similar to the Vashon Island firing except most pieces had no terra sig on them. They were all bisqued to cone 06. Here is what I have written down in my notebook about the pit layout:
The pots were mostly in a single layer (only 2 small pots were on top of other pots.) Copper carb was used more sparingly than the Vashon firing, and there was none on top of the pots. Besides the usual salted raffia, Chore-Boy copper netting, and steelwool strands that I brought, the participants also used copper wire of different sizes, inclulding some heavy gauge ones, as a fuming material.
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Besides toying with Chore Boy copper netting and steel wool, I also performed some other experiments in the Vashon Island pit firing last month. Here is a brief summary of these other experiments:
One experiment involves a piece which was completely unburnished, with no terra sig applied, and with a strongly textured surface from the thickly painted engobe. As you can see, the result (figure 1 above) has a very different quality from those other highly burnished pieces. Nevertheless, it is quite charming in its own way — there’s something simple and bold, and almost more honest about it… (perhaps because it’s less self-consciously trying to be beautiful?)
Packing materials: the usual cast of Chore-Boy, steel wool strands, salted raffia and salted burlap. The visible black and white net-like pattern apparently came from the Chore-Boy netting.
One of the experiments I performed at the Vashon Island pit fire last month involved the use of steel wool as a fuming material. I was curious about steel wool because I had thought it was the cause for the beautiful colors on a very nice piece from my first pit firing back in 2002.
Well, I am still not sure — now that the experiment has been performed — if steel wool was behind the colors on that earlier piece, but as you can see in figure 1 above, the fuming of steel wool can certainly generate some truly wonderful color patterns on a receptive (i.e. terra sig coated and highly burnished) surface.
I wrote a while back that, for my first pit firing, I got some very nice fuming effects from a disemboweled Chore Boy type copper scrubber; but I was unable to reproduce the same effects ever since. Well, at the most recent firing I finally managed to get similar colors (and then some) with the same setup — and so here is the report…
I had seven pieces in this firing, two of which were intended as Chore Boy experiments. The first is a small pinched pot (figure 1 above) with two layers of packing materials, both very tightly wrapped around the pot:
The feathery, wiggly lines in the deep red area apparently came from the copper netting that had started to disintegrate in that area. What’s unclear, however, is whether the larger, solid, and brighter red area to the right also came from the same. Or maybe it came from the admittedly plentiful copper carb in the pit instead?