Our obsession with brick ovens is a fascination with the ability to harness fire itself. Ever since Prometheus stole lightning from Mt. Olympus, we've been entranced by the power of an unpredictable flickering flame. Although we've been baking breads in simple brick enclosures for six thousand years, ovens still carry an air of mystery that we can't seem to shake. I'd like to take a close-up look at perhaps the most enchanting of pizza baking structures: the coal-fired oven. The once-necessary-then-obsolete-now-re-popularized coal oven has an interesting past that traces the story of pizza development in the Northeastern USA.
Those who have experienced the goodness of a coal-fired oven may take for granted the resulting pizza's crisp yet chewy texture, but how did these chunks of black rock get into our ovens? Coal was already a dominant heating fuel when Neapolitan immigrants landed in the United States in the 1880's. Newly arrived bakers used hard coal instead of wood to heat their ovens because it took up less space and burned more efficiently. A cord of wood (8 ft x 4 ft x 4 ft stack) weighs twice as much and takes up double the space as a ton of coal while both have the same heating capacity. So it's cheaper to transport and store coal, which is important when storage is at a premium.
The biggest difference for bakers is that wood contains water whereas anthracite* coal is approximately 92% carbon, so the latter provides a much drier baking chamber. Wood smokes as it burns, but coal does not. That's why chimneys fed by wood-fired ovens have to be cleaned more often than their coal-fueled counterparts. Coal ovens are also built differently to facilitate the unique requirements of the fuel. Since it burns best with constant oxygen supplied from beneath, coal sits atop a cast iron grate. The grate also allows ash to fall into a separate chamber so it doesn't contaminate the oven floor.
You'll recognize a coal oven when you see a firebox located to the side of the oven door, usually a bit lower than the floor of the baking chamber. There will also be a handle protruding from the oven face on the side opposite the firebox. That handle is your damper, which controls the flue opening and regulates your heat draft. This location allows air to move across the oven hearth and out the far end of the chamber. No need for a fan, just natural suction!
The oldest coal ovens were originally built as bread ovens. They would be fired daily until the chamber reached proper baking temperature, after which the fire was removed and bread baked on the bricks' stored heat. The jump to pizza came with the food's increase in popularity as more Southern Italians entered the USA, but the ovens remained outfitted for bread production. These beasts are so large that they were often built outside the buildings in which they continue to reside. Take a look at the building's profile next time you visit a century-old coal-fired bakery or pizzeria and you'll see a multi-story building that drops to a single level extension. There might even be a visible shift in brick color or a line where the construction began. Bakeries/pizzerias that still use century-old coal-fired masonry ovens include Lombardi's (original location AND current location), Parisi Bakery, Luzzo's, Verde (Bushwick), 18th Ave Bakery (Bensonhurst), Royal Crown Bakery (Bensonhurst), Frank Pepe's (New Haven), Sally's (New Haven), DeLucia's Brick Oven (Raritan, NJ) and Little Rendezvous (Meriden, CT).
Most of these surviving ovens are known as Scotch or black ovens because the coal burns inside the baking chamber. The other coal oven type, white ovens, are loaded through a completely separate compartment in the back and feature pipes that direct heat into the baking chamber. These ovens are much more manageable than black ovens but they can't get quite as hot. The only white oven I've seen in a pizzeria is at Modern in New Rochelle, NY but it was converted to oil sometime in the mid 20th century.
By the 1920's, new coal-burning ovens were available in stainless steel frames for better mobility and a smaller footprint. Still quite large by today's standards, these manufactured ovens were being used for small bread production and pizza. They function exactly like their big brothers but tend to be more efficient. You can still find them in use at John's (Bleecker Street), Totonno's (Coney Island) and Arturo's (Houston St). These were built locally by the Universal Oven Company and date as far back as 1924.
Most coal-fired ovens exist in the Northeastern US because that's where our nation's largest anthracite mines are located. Shipping coal to the west coast was possible, but not economical. Any glimmer of coal was crushed when the Federal Fuel Administration prohibited shipments of coal to the western states during the first World War. The ban provided a perfect opportunity for more efficient fuels like oil, gas and electricity to pick up the slack. Just as it replaced coal in home heaters, natural gas was the big winner in pizza ovens. Nobody cried for the loss of coal, which was dirty, heavy, required storage, and demanded constant supervision. Gas ovens turn on and off with the flick of a switch and bake more easily than their predecessors. There's a romantic idea that coal ovens are incredibly rare in New York City because they were outlawed, leaving only those with previously existing ovens "grandfathered in," but I have found no such law in the building code or Clean Air Act. The truth is that coal ovens are rare because nobody wants to deal with the hassle.
Plenty of new coal ovens have been built in NYC and the rest of the United States in the past 15 years. Los Angeles-based Earthstone Ovens has shipped over 130 units in the past few years, starting with the now defunct Lombardi's location in Philadelphia. Chains like Anthony's Coal Fired Pizza have introduced this oven style to customers all across the country, specifically in the chain's home base of Southern Florida. Anthony's slogan "Our pizza is well done" attempts to educate their customers that the pizza is charred—not burnt. It's a new concept for some and a reminder of New York for others.
*For more information about anthracite coal, visit the Anthracite Heritage Museum in Scranton, PA. Trust me, it's amazing.
About the author: Scott Wiener runs tours of significant NYC pizzerias with an emphasis on the history, science, technology, economics and deliciousness. You can sign up for a tour at scottspizzatours.com or follow his pizza explorations on Twitter via @scottspizzatour