I spent two weeks in a fog of brick dust, aluminum products, and cement powder the month I built the masonry pizza oven at my restaurant Il Forno. It took a steroid shot to get my lungs back to normal. That was five years ago, and my stance on protective gear was reckless at best.
Years ago I got my hands on an obscure book coveted by serious professional bakers. The Bread Builders, by Alan Scott and Daniel Wing, explores the ancient, elemental, almost spiritual relationship between food, fire, and stone. Wing presented pencil sketches of the most primitive ovens all the way to photographs of the most ornate, perfectly carved stone ovens of the Gothic period. He described in great detail the physics of draft, the thermodynamics of heat transfer, and the conductivity of materials – not to mention the chemistry and biology of natural yeasts and fermentation of dough – inviting us down a dark and twisting passageway into the primordial soul of cooking.
I was hooked.
I made a very primitive oven-like contraption in my backyard from big sandstone chunks I found around the property. That was a disaster. The rocks exploded like grenades. Then I made a series of clay ovens. That was marvelous fun (and cheap), and they hold up amazingly well. And it was in no small measure the impetus of this book that made me decide to build a pizza shop, based entirely on an oven that I would make myself.
With an imagination full of Puebla Indians, Spanish missionaries, and Roman arches, I decided I would not use one stick of modern structural innovation: no beams, no screws, no steel, no frames.
The base alone, which resembles the Arc de Triomphe rendered in black concrete pavers, weighed in at over 1,000 pounds and took two trips with the truck to gather materials for. First I made a long, tunnel-shaped wooden frame out of cheap wooden slats to guide the bricks in a curve, sticking them together with Portland cement. These materials would only be stable up to around 500 degrees Fahrenheit, but that was OK, I reasoned, because the real hot business would happen far above where I meant to employ the good-quality, high-heat stuff.
On top of the brick platform, in accordance with tradition, was a thick layer of sand for the firebricks to rest on. I carefully laid out a straight, flat floor – what would come to be called a “hearth” – and carefully built up the dome of firebricks that would surround it. Where walls are straight, it made perfect sense that bricks are flat and parallel. But when the wall begins to curve inward, math starts getting weird.
For the bricks to press against each other, there must be something wedge-shaped to exert that force (hence the Roman invention of the keystone, which is tapered like a trapezoid). Lower down on the walls I used refractory cement to create this wedging effect, and as the heavy stone curve leaned over and approached dangling overhead, it became clear that the firebricks themselves would have to be carved on four sides.
I used an electric tile saw with a diamond blade to cut the angles. The blade did not reach all the way through the brick, so I had to cut half from one side, then flip it over and do the other half from the other side. I would mark each brick with a Sharpie, then holding the brick I would cut them freehand and hope the cuts matched up. (I ruined a lot of bricks.)
The interior dome made out of those big, chunky firebricks is meant to absorb and hold heat for days, weeks, even years. The next layer is intended to insulate. Opting for tradition again I chose vermiculite, a kind of lava product, for insulation. It looks a little like Rice Krispies of stone and can take 2,500 degrees without a hiccup. I tossed it with a light cement slurry, just to hold it together while I got it packed on the dome to a thickness of about four inches.
When mixed with Portland cement, it caused a cloud of strong ammonia, like a super overripe cat pan, burning my eyes and lungs. I let this set for a day to firm up, although it was never quite got there.
Last was a thick shell of Portland cement to hold everything together, which I ran my fingers through in a swirl resembling the print of my right thumb. Then I painted it with black tractor paint.
And off we went full blast, pouring in a storm of wood and pouring out a storm of pizza.
The structural strain on a masonry oven is just incredible. These things ride between 700 and 1,000 degrees Fahrenheit (that’s almost the melting point of aluminum) about 200 days a year. Whenever it heats, all the joints expand; then when it cools they contract, changing shape slightly and relaxing into a different position. It boggles my mind how any brick oven can do this and not fall to blazing pieces.
The first cracks in the dome appeared in months. Smoke started to escape the cracks, but the oven held. It was the mouth that started to go first. We were terrified. “God, there goes the restaurant,” we thought.
After rebuilding the busted-up mouth once myself after about two years, we had a professional oven builder come out (to my great shame) and install an aftermarket mouth of his own. This in turn started to fall (to my mild amusement), and I welded a steel collar to put in the mouthpiece and hold the bricks up. Nobody knew then that changing the shape of the mouth would take away the pressure that held the bricks in place up in the dome. That brought us to year four.
The base began to spread, spaces appearing between the hearth bricks and squeezing the outer bricks out both sides. To hold that together, I welded some steel straps and screwed them into place around the corner bricks. (A steel band all the way around to hold the guts in is in the planning stages.)
Then, one day a brick fell out of the dome, and we knew we were in for it.
I pushed the bricks back into the holes and put my head and torso inside a 400-degree oven (because it takes three days we never have for the oven to actually cool, so no cement or anything can dry or cure properly) to drive in little pieces of metal (even a butter knife once) to try to keep the bricks from slipping back.
When the third brick fell out, I knew I had to take drastic measures. It cooled for three days before I began the most serious repair I have ever done.
The repair took me 27 working hours in late November. We were against the clock because the restaurant is almost useless without the oven. In the repair this time, I included a thin layer of fiberglass to allow some “slip” between the layers, in the hope that the movement of the firebrick doesn’t crack the outer shell. This time I used lots more “keystone” shapes in the dome reconstruction, realizing now that refractory cement can break down and stone-to-stone contact is just a better bet.
The oven must sit unbothered for five days to cure (which it did all week), then a succession of smaller-to-larger fires are lit in it each day, “warming the oven up” to the idea of being 1,000 degrees. On a Wednesday we lit the first fire. By the following Friday, we were able to cook an actual pizza.
It reminds me of life somehow: wonderful and precarious, each service a tiny little miracle. It could crumble at any minute. And yet, what joy it brings.
