How to Barbecue Your Pots
Warming the pots on the upper rack
Firing set-up with fan
Pots buried in coals, top temperature
Decorating pots with hair and combustibles
I developed this method for firing pots in a barbecue when I lost my studio during the 2020 covid-19 pandemic. It is based off of this Ceramics Monthly article by Sumi von Dassow.
A charcoal barbecue
Hardwood lump charcoal (not briquettes, they won't burn hot enough)
An electric fan and extension cord
Barbecue tongs (make sure they aren't made of a material that will melt)
A bucket of water
Light the charcoal like you would to barbecue. Making sure your pots are completely dry, you'll slowly start to introduce them to the heat. A barbecue with an upper rack is ideal for this step. The important thing is to keep the pots away from direct heat at first. I leave them warming up for about half an hour, incrementally moving them closer to direct heat. You'll have a lot of loss at first, figuring out where the heat is on your grill, how thick/thin/evenly you make pieces, how patient you have to be, and how much you can push it. I'd recommend wearing glasses when you're working around the grill at this point because pots will explode and send shrapnel flying at your face.
After about 30 min, when the pots are warmed up, you'll remove them from the grate and nestle them directly in the coals. Push the coals around to make space for the pots. Just like a bisque, you can stack the pots together no problem. Then, pour more charcoal on top of the pots, trying as best as you can to cover them completely.
Get as much oxygen to the pots as possible. I set up an electric fan on one side of the barbecue, as close as I could safely get it. Chances are you don't have a pyrometer, so you'll be judging the heat from sight. I've been able to get the charcoal glowing bright orange with enough oxygen, which puts the temperature above quartz inversion. It's still going to be low-fire and brittle, but it will be fired.
After about an hour in the coals, give the fire one more blast of oxygen and heat for good luck and the take the pots out, raku style (if that's what you're going for). I've used the metal lid of a garbage can and metal baking trays to place my hot pots on, and I've used an empty metal coffee canister to smoke my pots. Just, of course, have a plan for where you'll put glowing hot pots.
Decorating Your Pots When You Don't Have Access To Many Materials:
Making a terra sigilata:
1-2 tbsp of deflocculant - I used sodium carbonate
To make sodium carbonate, spread some baking soda on a baking sheet and bake for approximately 30 minutes at 350ºF. The powder will become more granular and slightly duller.
I've had success applying my terra sig to bone dry pieces (3 thin layers) and buffing gently with a rag from an old cotton shirt.
Black and greys are easy - just smoke the pots with combustibles. For a deep black, I smoke the pots in an old metal coffee canister. Hair held to the hot pots will leave wiggly black/metallic lines and smell awful as it burns. Sugar sprinkled on will give small black dots and smell like candy.
Iron - I marinated some old nails in a bit of water to make iron oxide. It's not as strong as studio-quality iron, and I'm not convinced it's totally fluxed but it does give some brown/redness
Pink - Put salt directly in the barbecue while the pots are firing for unpredictable salmon blushes and rusty spots. When the salt directly touches the surface of the pot, it leaves strong rust spots and can leave texture. If the salt vaporizes near the pot without touching it, then you'll get more subtle blushes.