It's interesting how sometimes one thing leads to another in unforeseen ways. I'm currently on one of these little adventures. Post firing reduction is a method used to impart a black, grey, smokey look to a ceramic piece, sometimes using glaze and sometimes not. Western Raku is one of the most well known forms of this and pit firing is another. For many years I have used variations on the pit firing method to finish my Podrums using different materials for combustion, etc. Most typically I would bisque fire the pieces to my desired temperature first, Cone 010 (aprox. 900*C) and then after they had cooled down I would place the drum in an old garbage can filled with newspaper, light it from the top with a blow torch and after a few minutes I'd put the lid on and let the whole thing smolder until done. Usually in about half an hour or so I was able to pull it out. If it hadn't received enough smoke I'd flip and repeat. This was working fairly well and I liked the quickness of it all but after losing a few too many pieces to cracking (thermal shock)I decided to change my approach. I now preheat the pieces to 450 celcius in my electric kiln before placing them in the bed of newspaper. This means the paper ignites almost immediately on its own and there are less hot and cold spots for the pot to contend with. I usually do this on dark rainy nights (not hard to find in Vancouver) so I just let things smolder slowly overnight and by the next morning it's cool enough to pull out.
The other interesting angle to this process is that the first drums I tested were ones that I'd burnished. Unexpectedly, some of my fingerprints were revealed after the smoke firing giving an interesting abstract finish. Wanting to play more with this altered, resist like finish I started gathering freshly fallen maple leaves from the trees next to the kiln shed. I placed these on top of the first layer of paper and then pressed the glowing pot into them before covering with more crumpled paper. The results have been very satisfying. The moist leaves don't burn as fast, therefore leaving the surface a bit lighter in that area. I have begun experimenting with different types of leaves etc. and am having a blast. The final step to this process is a light coat of floor wax to bring out the shine. Although their low fire porosity means they won't hold water, these pieces are perfect for showcasing dried flowers or interesting branches. As with all ceramic endeavors, one small change in protocol can lead to something completely different. I'm not sure where this adventure is going next but it sure is satisfying and if you see smoke rolling down Railspur Alley don't call the fire department, it's just me.