Tuesday, January 31, 2012

Brick Oven Curing

In the process of building a brick oven a number (3-8) of gallons of water are used to mix mortar, insulating layers, and outer shells of stucco etc.
This water will evaporate very slowly on its own.
Curing the mortar requires that we leave it moist for at least a couple of weeks. Following that a warming fire is lit in the oven and the bricks are heated gradually.  When the radiant heat reaches the moisture in the masonry it drives it outward. This is where you want to give it somewhere to go. If tightly enclosed, an oven at this stage will weep water that has condensed on cool outer surfaces making it seem as if there's a sprinkler running above the dome.
evidence of a good draft in the throat
So start small and go slow. Then close up the oven mouth and let the heat radiate. Do this a couple of times, increasing the fire  until the oven is 'up to temperature'. This can be measured visually (carbon burns off the roof of the dome at about 600 degrees) or with probes or infrared thermometers.
It may take a few real firings to get all the moisture out and you may smell the steam from the heating but eventually you'll have a thoroughly dry masonry unit.

Monday, January 30, 2012

Brick Oven Insulation

antique French oven
Unlike brick ovens of colonial era and earlier, modern wood-fired brick ovens seek to keep the heat of the firing as long as possible using relatively high-tech insulating materials.
vermiculite mix

The simplest of these is vermiculite, or expanded mica. These particles, easily found at greenhouse and nursery supply stores, are fireproof and full of air.  Mixing them with a small amount of Portland cement allows you to cast shapes that will provide rigid insulating barriers. I have used loose vermiculite as a final filler in ovens of mine that have a ''house" type enclosure. 'Insulcast' a Mt. Savage product, duplicates the vermiculite/cement capabilities with a controlled albeit more expensive product.

Foamglass, Fiberfax board and brick
Insulation beneath the oven needs to be rigid and strong before the first layer of firebrick for the oven floor is laid. Again, vermiculite/Portland cement is a low-cost option but this needs an additional concrete slab below it to provide tensile strength. 
Foamglass, a refractory insulator, comes 4" thick in slabs that can be easily cut with a handsaw. It is expensive but very effective. 

For the outer part of the oven, ceramic fiber blanket can be layered to any depth to provide a high-temperature barrier.

The long and short of it is: more insulation holds heat longer. If that is your goal (a 30 hour cooking window per firing) then more is better.  I've "over-insulated" the house I designed and built for myself. The result is one-fifth need for whatever fuel source heats it.  Kind of a no-brainer.

Saturday, January 28, 2012

Indoor Brick Oven Construction: Part 4

view up throat
brickwork above throat
Once the dome, the mouth and the throat of the oven are built, accommodations are needed to get the flue gases out of doors.  Truly, indoor brick ovens need to be especially adept at preventing smoke from invading the living space. Aside from the obvious annoyance of smoke, the remnant odor and its tendency to trip smoke alarms make this an important detail.

open flue channel
chimney connect
The illustrated oven additionally needed a flue channel that directed the smoke over the dome so that the insulated metal chimney passed through into an adjoining attic space and up over the roofline. The flue channel was built with standard firebrick and large slabs of firebrick panels and runs approximately 30" horizontally before it converts to the thimble connecting it to the metal chimney.

Insulating concrete was used to build a bracket for the flue channel.
Following blogs will illustrate the complete insulation and surround of the oven.

Friday, January 20, 2012

There are bakers and bakeries and there are BAKERS AND BAKERIES. Whenever I was in Portland, Maine, I stopped into Stephen Lanzalotta's bakery, Sofia's. There I discovered that transcendent bread (in the form of Lunas) and remarkable pastries DO exist.
Prior to my forays to Sofia's, I never imagined that pepper had a place in confections or that confections don't have to shout SUGAR to get your attention. What I have learned since is that Stephen is perhaps unique among all bakers.
Before my first trip to Italy in 2006, I asked Stephen where I might learn Italian and he steered me to Paola D'Amato at the Institute for Italian Studies in Portland (www.iismaine.com/)
Born and raised in Trieste, Paula guided me and the other students in conversational and written Italian. Having had a solid base in Spanish I managed to morph with the intermediate class and arrived in Italy that November ready to adventure into the countryside.
For the last twenty years Stephen Lanzalotta has played with the idea that there are inherent ratios in nature, including the “golden section,” and if you obey them, good things will happen. He has baked his bread using ingredients measured to certain ratios that he believes were discovered by ancient Greek and Egyptian mathematicians, and which have been used throughout the ages by the great artists, architects, and inventors — indeed, which he uses in his own paintings, exhibited at Sophia’a and another Portland art gallery. When Sophia’s bread sales dropped precipitously during the Atkins diet days, Lanzalotta fought back with a diet that he concocted using his numerological techniques, and for the past three years he has been lecturing his bemused customers about his ideas. The popularity of Dan Brown’s Da Vinci Code gave him another opportunity to popularize his theories, and helped him land a book contract for a diet book to be published next April by Warner Books (pictured).
Lanzalotta recommends 20% protein, 52% carbohydrates, and 28% fat (see diagram below), deriving these percentages by “linking together exponentials of phi.” Phi (φ, pronounced “fee”) is the number 1.618, the so-called golden ratio.
Other numbers incorporated in Lanzalotta’s diet are 144 (the dozen dozen), 360 (the optical plane), 432 (the Vedic earth revolution age), 666 (the number of Mephistic planes in the Louvre pyramid), and 756 (the length in feet of the great pyramid of Khufu).

Lanzalotta, who used to turn out 60 different kinds of bread at his Sophia's Bakery in Portland, downsized about four years ago and set up shop in Micucci's to focus exclusively on the pizza (and a few other specialties including flaky sfogliatella, focaccia, and a hearty seed and nut loaf produced only on Fridays).

It so happens that Micucci's Grocery (a REAL Italian grocery) www.micucci.com/ has been my favorite store in Portland for the 40 years I've lived in Maine. Now I can stop in to smell and buy the piquent cheeses and salamis in front and wander past the pasta and wine racks to the baker for some of that amazing food that Stephen Lanzalotta turns out with spellbinding regularity.
Thanks to the writers at calorielab.com for the review of The Diet Code and to Paula at the Instituto for helping me enjoy Italy.

Wednesday, January 18, 2012

A Brick Oven Builder's Geneology

Kiln shed and wood pile a lot like my old one

Almost identical kiln to my old one
I can trace my interest in building brick ovens back almost 40 years. In the mid-1970's I was making wood-fired stoneware and porcelain pottery. As a ploy to lure customers down the back road and quarter mile path to my pottery, I made a large batch of bread dough. On the morning following the 2100 degree (white hot) firing, the kiln had cooled to 500 degrees and using fireproof gloves, I removed the pots from the top kiln shelf and slid the bread pans of dough into the kiln. Twenty minutes later I and my customers were enjoying the most perfect bread. Whether I sold any pots doesn't stick in my memory as well as the bread.
A recent 48" oven I built
Fast forward 30 years. I'm still baking bread. I've been a professional landscape designer and stone mason for a dozen years. The bricks from my old kiln have been gathering moss. A few friends talk about building ovens. I have an old work trailer capable of carrying a ton or more.
My first oven (still in use) was built on the Pompeii model, a style I still advocate. Those old bricks, some of which were witness to bread baking many years ago, now see dozens of meals, bread, roasts, pies, pizzas as well as the people I feed.
My first brick oven

As a potter, I burned 12 cords of softwood a year. As a baker I burn an armload of hardwood each firing. If anything, the bread has gotten better.

Thursday, January 12, 2012

Wood-Fired Portland

Portland, Maine reputedly has more restaurants per capita than any other city in the country. Fortunately it is de facto Maine's and my locus of activity (despite its frequent use in the above sentences, Latin is not Maine's native language).
Two prominent restaurants feature wood-fired ovens. I recently stopped into Fore Street (located on. duh, Fore St.) and Flatbreads (on Commercial St.)
Their ovens differ greatly in design but function well for the food they specialize in.
Fore Street has a sprung-arch rectangular oven, visible from the dining area, and set behind a work station. At two in the afternoon, the fire was stoked for roasting and ingredients set out in preparation for the evening's influx of customers.
The oven face, finished with brick and a black keystone, gives a sophisticated impression, and the restaurant is known for its well-prepared food.
Flatbreads oven is a rustic assembly of stone and cob with a central fire and raised cooking hearths on the left and right. From the color of the interior, the baking of the thin-crust, lightly topped flatbread pizza is done using reflected heat from the central fire.  The oven vents into a large exhaust hood above the oven.
Of the two, I found the Flatbread oven had a primitive, communal feeling. I'm told that teams of co-workers gather for a day and 'throw' one of these together. The hand-print and roughly shaped crown of the oven, all set atop a rough stone foundation make the effort to build it appear relaxed, despite the approximately 4 tons of material that go into the construction.
Make no mistake, if you go to Portland to eat, you WILL be distracted by dozens of fine restaurants even before you reach either of these two establishments.