Pit Firing Using a Good Old-Fashioned Charcoal Grill

As Sumi von Dassow explains in today’s post, you can get great pit firing effects on pots using a good ol’ charcoal grill. And, with so many people switching to gas grills these days, you could probably find a cheap charcoal grill at a garage sale, or you might even have one in the back of your own garage!

So if you’re looking for a fun activity to try out in your studio, read the article and start experimenting with this backyard pit firing technique. – Jennifer Harnetty, editor.


 

Pit Firing Without the Pit!

If you don’t have a kiln but still want to fire some pots—or you have an electric kiln but you’d like to do some smoke firing without digging a fire-pit in your yard or alarming the neighbors too much—the grill is a surprisingly versatile alternative. Yes indeed, your trusty old Weber grill—the little round one on three legs that you might have left sitting in your garage when you upgraded your outdoor kitchen—can have a second life as a mini-kiln.

I used a 22½-inch round grill, achieving a variety of effects with several kinds of clay and surface finishes. In order to replicate the look of Native American pottery fired in outdoor bonfires, I fired pinch pots and small wheel-thrown pots made from micaceous clay. This clay incorporates small particles of mica in addition to grog, which makes it beautiful as well as very resistant to heat shock. In New Mexico it’s traditionally used to make flame-ware for cooking directly on a fire or on the stove-top. I also tried a variety of smoke-firing techniques on pots made from smooth stoneware clay that was burnished either with a stone or using terra sigillata.

Pit Firing Pottery in a Weber Grill

To pit fire greenware on the grill, make pots with walls that are about 3/8-inch thick throughout—no fat bottoms or thin rims—and dry them thoroughly before attempting to fire them. You don’t need to use micaceous clay, but use a clay which is resistant to thermal shock such as raku clay, groggy stoneware, or paperclay.

Make sure the grill is clean, removing any ashes or partially burned coals in the bottom, then get it going just as you would for cooking, pouring lighter fluid over mounded charcoal and lighting it. Note: Wear gloves and protective eye wear whenever handling pots around the grill, from placing them onto the grid to taking them out of the coals after the pit firing. As the coals gradually begin to smolder, preheat the pots on the cooking grid above them.

Fig.1 Lift out the cooking grid, spread out the coals and put the preheated pots on the coals.

Fig.2 Cover the grill but leave the cover cocked to allow for air flow.

Fig.3 Surround taller pots with wood scraps. Use newspaper to encourage the wood to burn.

After 15 minutes or when the coals are turning gray at the edges, quickly and carefully move the pots, remove the cooking grid, spread the coals out and place the warmed pots directly in the hot coals (figure 1). Spread the coals out as you would for cooking, and nestle each pot into the coals. Cover the grill to retain heat, but leave the cover cocked for better air flow (figure 2). Be careful not to rest the hot edge of the lid on the plastic handle of the grill! Out of curiosity, I put a pyrometer inside one of the pots in this firing, and it registered as high as 1300°F, or approximately cone 018. After 30 minutes or so, your pots can be removed. Test them by tapping them to see if they ring, or scratching them with your fingernail. If your pot rings when you tap it and you can’t scratch it easily, it’s fired. Of course the clay won’t be fully vitrified and your pots won’t hold water, but the finished pots won’t disintegrate in water as greenware would. Coals alone reach a temperature of at least 1100°F, and will be enough to fire small pots. For pots above two or three inches tall, or to increase the firing temperature, you might want to pile wood scraps around them to ensure an even firing temperature from the top to the bottom of the piece (figure 3). To increase the heat even more, you can try blowing air into the grill with a fan (figure 4), though it’s possible that doing this repeatedly could shorten the life of the grill, particularly of the charcoal grate. Adding wood to the fire will make it smoke more and consequently the pots will come out with more smoke-markings.

Alternative Surfaces

For a beautiful decorative effect similar to horse hair raku, place horse hairs (or other animal or human hair) on the pot immediately after removing it from the fire (figure 5). When working with this technique, remove the pot using tongs, and place it on a piece of warmed soft brick to avoid cracks from thermal shock. The hairs will burn and leave squiggly black marks on the pot (figure 6). Have the hairs ready and work fast—you may only have a few seconds before the pot cools down too much.

Fig 4. Use a fan to increase air flow and heat.

Fig 5. Place horse hairs (or other animal or human hair) on the pot immediately after removing it from the fire.

Fig 6. Finished pot with horsehair decoration.

For other alternative pit firing effects, try burnishing your pots with a stone or applying terra sigillata. Depending on the type of clay you are using, you might want to bisque fire them in an electric kiln and use the grill for decorative effects. I create patterns on pots with copper foil tape (intended for stained glass work), gold leaf pens (figure 7), or masking tape (figure 8). Decorated pots can then be wrapped with a double layer of aluminum foil and placed either directly on the hot coals or on the cooking grid for 30 minutes (figure 9). I placed these tape decorated pieces on the cooking grid instead of in the coals because aluminum foil disintegrates when placed directly on the coals, which can allow smoke to blacken the pot too much. Since the grill can’t produce enough heat to burn off the adhesive on the copper foil tape, this needs to be scraped off after the firing.

Fig.7 This sphere has designs drawn with a gold leaf pen and lines made using copper foil tape.

Fig.8 This pot was bisque-fired to cone 010, masked with tape, and brushed with terra sig.

Fig.9 Place foil-wrapped, tape-decorated pots on the cooking grid rather than on the coals as the foil disintegrates in high heat.

 

Fig.10 A white stoneware lidded box with masking tape resist decoration after a smoke firing in a Weber grill.

I’ve found that different brands of masking tape can have very different effects-—some burn quite quickly and may leave your pot completely black if left on the grill for the full 30 minutes, while other brands have a great deal of sticking power, provide a strong resist and need to be scraped off after firing. The white stoneware piece (figure 10) was brushed with terra sigillata, bisque fired to cone 010, decorated with masking tape, wrapped in a double layer of aluminum foil and fired in the grill.

One more beautiful effect you can easily achieve pit firing in your grill is the rich glossy black of burnished and smoke-fired Pueblo Indian pottery. For best results, burnish a smooth red stoneware clay with a stone. If you want to bisque-fire it in an electric kiln first, fire it only to cone 018 to retain the burnish. To blacken it in the grill, wrap it in newspaper and then aluminum foil and place it in the coals. For a deeper black, place it directly in the coals and surround it with wood scraps.

When the wood is burning merrily, cover the grill, shut the air valve on the grill cover and close the cleaning valve on the underside. To protect the burnished surface from getting scratched or marked by the fuel, you can follow the same general steps but start by placing the pot in a coffee can or cookie tin that has holes pierced in the sides. Nestle it into some wood shavings at the bottom of the can, place the can into the coals (figure 11), and cover the can with aluminum foil or a piece of kiln shelf (figure 12). This way, smoke can surround the pot but the pot won’t be in direct contact with burning wood or coals. After 30 to 45 minutes, when the grill has stopped smoking, the pot can be removed. If the pot wasn’t bisque-fired beforehand in an electric kiln, you’ll need to carefully preheat it and fire it directly in the coals to get it hot enough to vitrify—but you’ll probably get the richest black color this way (figure 13).

Fig.11 Place a burnished pot inside a perforated coffee can prior to firing to create an even, glossy black surface.

Fig.12 Surround the coffee can with wood scraps to create more heat and smoke. Cover the opening with a piece of kiln shelf.

Fig.13 A red stoneware, stone burnished pot, bisque-fired to cone 018, placed inside a perforated coffee can and fired in a Weber grill.

I’m sure I’ve just scratched the surface in exploring the possibilities offered by this simple piece of equipment. Playing with fire in your barbecue grill makes for an easy and fun project you can enjoy by yourself or with your family—so break out the clay, get some charcoal, and fire away!

Clays used

Micaceous clay is available from: Coyote Clay – www.coyoteclay.com
or New Mexico Clay –  www.nmclay.com
You can also buy powdered mica and add it to your own clay body.

Red clay for burnishing: Navajo Wheel from Industrial Minerals Company – www.clayimco.com

Sumi von Dassow is a frequent contributor to PMI, the author of the best selling book Low-firing and Burnishing as well as the producer of the new DVD Pit Firing & Burnishing. For more information, go to www.herwheel.com. Her book and DVD are available in the Ceramic Arts Network Bookstore.

Comments
  • Fantastic! I in for some fun on the Bar-bee.
    Fun

  • Michelle L. B.

    Making cane handles, pouring molds and now barbecue pit firing. How much do I love Ceramic Arts Daily this week? Can’t be measured. What a fantastic community.

  • Hello Everybody, Really it is a good idea. I have a grill built from stone. it is enough deep. I’ll try to fire with sawdust next.If you think I share with you the result of fireing.

  • I love this place, every day brings fabulous new ideas and great tips for solving everyday challenges. This charcoal idea is just absolutely fantastic!

  • Katreen K R.

    Please avoid using sawdust, it is extremely combustible, and also may be filled with preservatives and toxins. I would suggest using the shavings that are sold for hamster bedding.

  • Never would have thought to BarBQue my bisque 🙂
    Can’t wait to try it!

  • Anne G.

    always knew this was a possibility but wasn’t sure how to go about it. found an old bbq at a garage sale and was waiting for inspiration. now i have it with directions. good job!

  • Margaret G.

    This is hilarious! We just improvised a mini Weber kiln a month ago. My 13 yr. old daughter, Isabel, made a figurative, terra cotta Inca vessel for a school project. Beautifully formed around newspaper, she forgot to put a hole in the piece to allow air to escape. We dried ‘him’ for 5 weeks, and fired up the bisque. Upon opening the lid come morning, shock! His head had blown off such force one of the shards knocked off the kiln sitter. A beautiful patina on the body confirmed a minimal firing of less than an hour. I had an eerie feeling the Inca gods were giving us a message…

    Isabel raised her chin, & sat down to make another head. We dried it in the oven and the San Francisco sun, w/ a day left before the project was due. But the head didn’t match the richness of the body…so into the mini Weber it went surrounded by newspaper,wood slats & countless giggles. After an hour of smoking it emerged,
    a perfect match to its body. E6000 Glue proved the trusted friend again, and a necklace of silver & turquoise beads hid his neck scar. Never had we heard of using a Weber before, and of course, here it is, circling the ether.
    Best to all.

  • Analia I.

    Buenisimooo!!!!me encanto!!!es genial!!!!

  • Susan C.

    I’ll have to dig up a kettle grill – mine’s barrel-shaped and probably wouldn’t work as well, but it sounds like fun!
    Being a purist on grilling – suggest using sticks and newspaper (rather than lighter fluid) to light the charcoal. They’re renewable.

  • Kathleen R.

    Wow, what fun! Too bad a friend just gave away his weber. My daughter’s gas grill is broken, so doesn’t function with gas anymore. I wonder if I could fire that up by using it this way? Comments, anyone?

  • Pilar B.

    what about using a backyard fire pit?

  • Kathleen R.

    Well, now that’s a good idea too, since we have the backyard to do it in. I think the grill idea is an option, especially for those unable to do a fire pit in their backyard. I actually think this might be fun to try, and perhaps an option for those with bad backs and joints…. it’s up at a higher level so no crouching, stooping, bending, etc.

  • this site rocks! Every day more and more great ideas come pouring forth. Can’t wait to try this one; here in San Diego we have the weather to do this anytime. thanks to all the editors and contributors for making this site so great; you keep us all inspired!

  • Jaci S.

    WOW! Everytime I open this site I am amazed. Today I was completely blown away. Thanks for an ingenious way to fire a pot without having the neighbors go ballistic.

    Jaci

  • Linda R.

    I’ve used an old grill for post firing my Raku for the last couple of years. It works great! Now I have another purpose for the grill.
    Thanks and happy firing everyone.

    Linda

  • Pete G.

    The “barbie” is a good place to do “foil sagger” work. Wrap a bisqued pot in foil, after sprinkling in stuff like salt, bare wires, or “interesting” plant materials. The idea is to use the foil wrappings to hold these things against the clay surface, so the heat will drive the resulting fumes into the bare clay. Miracle-Gro works nicely, so do shredded copper scrubbing pads, bare copper or brass wire, seaweed (especially if it’s still laden with salt), and I especially like to use leaves and thin vines that have been pre-soaked in brine…kind of a “low-fire Bizen” effect. Other metallic salts work well too, but use caution, as some of these can be toxic.

  • Christine P.

    I was just wondering what to do with the old rusted Weber.. I got a new, smaller one for myself.
    Now I know exactly what I’ll try!
    Oh my gosh! I can hardly wait..

  • Vikki R.

    Thanks for the great ideas. We are about to do a pit firing this Winter at our Pottery shed & all the ideas help. I can’t wait to try the ‘Webber’ idea too. Maybe in conjunction with the pit firing. Thanks everyone.

  • Pat H.

    I have a 3x6x4ft. deep pit in my back yard (on a farm). We have used it for pit firing and it worked quite well, but it is a lot of work to set up and fire. We have heard of firing in a barrel as well, but have not tried it yet. I wondered about putting cinder blocks in the barrel to protect the pieces a bit.
    This idea of the BBQ would work great for anyone living inside city limits!! It would also be good for anyone who fires smaller items – figurines, jewellery,etc. I’ve been looking for a tabletop kiln for such a purpose – this might be the solution. Thanks a lot for all the information!

  • Yossi S.

    great idea thank you

  • Halema A.

    Thanks for the great ideas

  • Yvette M.

    Fantastic idea! My husband makes wrought iron braziers and ‘Weber’-type bbc’s, so I have a choice to experiment with. Thank you!

  • Dolores B.

    Would this method work for raku glazes?

  • Pete G.

    The only way to get any sort of glazes to melt in a pit-fire would be to use a blower to help raise the heat of combustion, and a surrounding of firebricks to hold the heat in! You’d need enough fuel, and enough draft, to get the ware up to a bright red heat, where most of the subtle nuances that happen in pit-firing would probably get cooked off. In other words, you need a kiln. But then…..you are no longer firing in a pit.

  • Michael G.

    I have no way to do raku firing at my home studio: it is in the middle of a city, and just lighting a cigarette will cause the neighbours to call the fire department. However, as long as I am doing what I am doing within the confines of a barbecue (even an old charcoal-burner), everyone accepts it as valid and no one bothers me. I have fired raku pots with raku glazes to cone 06 in my 12 cu. ft. electric kiln. After the kiln is cooled, I re-heat the pots as Sumi advised over a charcoal “fire”, and when fired, immerse them in the charcoal. As Pete says, the temp is not high enough to melt the glazes, but the surface is still porous and the clay gets the smoked colour. The glaze also changes, with the smoking. The glaze I use is a lithium-based glaze, quite coarsely textured. So far the effects on the glaze have not faded or changed, although they might do so after some time…it’s not raku, but it works…

  • Michelle H.

    great idea thank you

  • I am so inspired! I have been busy taking accounting classes in college and my love of raku and horsehair firing has diminished behind alot of accounting numbers. With God’s grace, I will soon be back in my studio and growing my own business around my love of ceramics. Thank you so much Sumi and CAD, I would be lost without you.

    How do you keep the wood from fracturing your greenware when placing it on the coals? The most obvious wording is “carefully”, but do you have any specific suggestions?

  • Patty O.

    On a recent trip to Nicaragua I visited a pottery that used a similar technique to “smoke” their pots. The potters there applied slip decorations to pots that had been fired once, and then put the pots into a traditional kiln amidst some already-burning wood. When the pots were sufficiently smoked, they removed the pots from the kiln and scrubbed off the slip. The areas that had been protected by the slip were a deep red-brown while the areas that had been exposed to smoke were a darker brown. For a detailed explanation, visit my blog: http://www.geist.com/blogs/pattyo/2010/02/day-5-nicaraguan-journal

  • Kassim N.

    الموضوع جميل ويستحق الوقوف عنده لكن هل توجد خسائر اثناء الحرق مع الشكر

  • Hilary C.

    I’ve been pit firing in a cast-iron backyard ‘fire pit’ for a little over a year now, and it works wonderfully. Here’s my blog entry about this pit — http://www.claymonk.com/blog/?p=43. Note the flames were generally much more mellow than shown in the photo, except during the initial 5-10 minutes of the firing; but if you’re still worried about drawing unwanted attention, you can start with fewer logs, and then add fresh logs more frequently instead.

    I’d love to try the BBQ method again, with charcoal as fuel this time as per your suggestions here. Thanks all for the great post and comments!

  • Subscriber T.

    okay-new to this-does anyone know if you can “smoke” unglazed tiles and then refire them with a clear glaze in an electric kiln?

  • Barb H.

    I AM NEW TO THE POTTERY WORLD BUT REALLY LOVE TO PLAY WITH CLAY.
    I HAVE MADE SOME FIGURES AND WOULD LIKE TO TRY THE BBQ METHOD. IT SOUNDS VERY EXCITING.
    MY QUESTION IS DO I HAVE TO BISQUE FIRE THEM FIRST OR CAN I FIRE THE AS GREENWARE?

  • Tracy W.

    greenware is OK but you might have some cracking. Be sure to preheat.

  • I am new at ceramics and also love to play and experiment with clay. I have just tried firing some greenware pieces and got some mixed results. I pre-heated my pieces on the grill as the coals were heating up, as per instructions in the article. One piece made it quite late onto the grill compared to the others and cracked…so it proved the importance of putting the pieces on the grill right away as you are lighting the coals.
    Two of my pieces that were nestled in the coals after pre-heating ended up desintegrating where they were touching the hot coals…Did I leave them in for too long? They were uniformely dark grey by the time I noticed that there were areas that were turning white and breaking off. Any advice would be appreciated, on this site or at josee@telus.net. Thanks!

  • Gelly J.

    Thanks for this inspirational article. I had a go firing my paperclay pots and cups in a metal pot and also rocket stove using wood and briquettes, but unfortunately each kept popping like popcorn and each pieces exploded. Perhaps it was because I heated the grill too quickly dumping all my fuel in at once, orglazed it before bisquing my pots and cups. Also I noticed that I was meant to leave it to cool for up to 30 minutes before removing it from the ‘bbq kiln’, but i took it out immediately and notice it was unevenly fired.

    I wonder if using a pyrolising grill (made out of two empty tin cans- unbelieveably cheap and simple, but powerful) will fire earthenware sufficiently since it can reach 1500 deg F according to this blog’s experiments.
    http://www.greaterdemocracy.org/archives/1084
    http://www.greaterdemocracy.org/archives/1116

    If anyone does try firing with the 2 tine can pyroliser please share your results. It might be a breakthrough on DIY kilns.

  • Gelly J.

    Regarding preventing cracks and sudden surprises, I was watching a Mata Ortiz youtube today and discovered how the potters prepare their pots for firing.They warmthem in the oven first and then put their beautiful black burnished pots on metal prongs. Cover with a metal washtub then surround the tub with ashes and wood. The wood is then twist tied together with wire to keep the wood upright against the wash tub. The fire is lit with petrol and left to fire.

  • Lezama J.

    This is a fantastic idea. I will try for some of my samall pots. We are a small group trying to do pit firing in differen´ways. Thanks for your ideas!

  • Ana G.

    This is a fantastic site. I have learned so much about the different teckniques and I am amazed at how many different ones there are. I do lmost small sculptures and I think I may try it in my gas grill.Thanks for the info

  • Gelly J.

    Hi Ana, a recent invention I found much more realiable for firing without a risk of explosionss or cracking is to make an earth clay oven with a mixture of clays, straws, earth, potash. You can watch the amazing oven / kiln here: http://www.youtube.com/watch?v=VypiS5X31aA

  • I love this idea.. I did exactly what you recommended I used a white lagunna 66 burnished stacked wood around the piece. Amazing results..thank you so much!

  • Thank you for this! I’m 16, and just experimenting with digging up my own clay – was looking for a way to fire it without having to have a expensive or large kiln – can’t dig up the yard, but I can use the old grill for this! Am going to make a wash of rust(iron oxide) and water to stain my wares before firing(red clay from my yard, grey clay from the stream, mixed) in this bbq kiln. I also found a one-use woven paper basket kiln idea on youtube i want to try – but this is easier for a first try.

  • Mattie A.

    Tried the barbecue grill method this morning. 2 pots in aluminum saggars, 2 wrapped in newspaper. Everything had been previously bisqued in an electric kiln to 09. All pots survived the firing. The newspaper wrapped ones are not as black as I would like so, I plan to re-fire them, placing each inside a tin can with wood chips. I love this method. Thank you, Sumi.
    Yes, I have your book and video.

    Mattie

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