Brick Oven Specs #3

angled mouth with door stops

I have been able to add one significant change to the design of modern brick ovens. 
In many of the modern brick ovens, the throat and flue sit above a deep recess between the face of the oven and the mouth.  This prevents both a sight-line and working access to the front edges of the dome's interior.

large shelf area

By angling this space at about 30 degrees (making the face arch of the oven about 1.8 times wider than the mouth) the baker has perfect access to all of the interior without changing the needed proportion of the mouth.

angle-iron chimney supports

 This complicates the geometry of the mouth when forming double arches with brick, but once accomplished the cuts are repeatable or, on one-offs, done with.

a bit of tricky geometry

Please note that this is not entirely original as both the old French ovens and the ancient Pompeii bakeries had very large openings in front of the mouth which served to provide ample access.  It also gives a much larger shelf space in front of the oven when handling baked products.
The illustrated methods here are suited for ovens that are smaller and self-contained.

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Brick Oven Cooking Opportunities

Last Thursday I teamed up with a local Italian guy (thanks Angelo) to make pizza for varsity team captains at a private academy nearby.
I rolled my portable around to the location for the end-of-year celebration and fired it up.  Some of the students who plan on building a brick oven as their senior project came by to observe and ask questions.  
When the oven temp reached 750 F we started turning out 2 minute pizzas...which were promptly woofed by the hungry captains.

Afterwards, I towed the oven back to my place and 5 hours later slipped a Challah (bread that is traditionally baked for the Jewish sabbath). into the 537 F oven.
The next morning the infra-red thermometer read 356 F.  24 hours from first firing the oven was 238 F.
38 hours from firing: 185 F and 144 F after 50 hours.  60 (sixty) hours after the initial pizza party the oven was still 126 F.

The above temperatures can be associated with cooking opportunities. Pizza, bread, oven omelets, roasts, puddings, slow-cooked ribs, dehydrated fruits and vegetables. 

Brick ovens that are well insulated take an armload of wood and convert it into almost three days of cooked meals.  After 4 years of building and cooking in these ancient devices, I'm still amazed at how "green" they are.

Brick Oven Mentors

The concept of mentorship/apprenticeship goes back to the dawn of time.  Nobody studied Mammoth hunting without seeing a mammoth, dead or alive.  They didn't sit around in a cave nook discussing the abstract and moral pros and cons of eating mammoths.  Their shelters were made of mammoth hides and supported by mammoth ribs.  They tasted mammoth, smelled mammoth, lived mammoth.

Following my traditional education (and even during it), I have filled my life with in-the-field learning.  I owe most of what I know to the community of actors, writers, masons, gardeners, and bakers with whom I have shared interests.
I enjoy mentoring others and have seen a number of young people I've mentored follow in my profession.

In a sense, I mentor myself, or place myself in situations where I am compelled to learn at a pace and intensity that would not be offered in traditional education.  My Spanish was learned "a fuerzas", by force or necessity when I entered, by invitation, a  village in rural Mexico that no 'gringo' had ever been in and for two months I heard and spoke Spanish ten hours a day.  I take the opportunity to learn other languages when I travel. But I digress.

Brick ovens offer a unique opportunity as a project-based learning tool. The history, culture, and mythology of food and fire is wrapped in the very appealing crust of brick, mortar, smoke, and bread.  The goal is clear.  The memory of all that surrounds the actual oven gets embedded in that most deep sense: smell.

This spring,  I will be advising a group of students in the building and use of brick ovens.  I also offer a mentoring/mason option for owner-builders who want to have a hand in their own oven but would benefit from guidance and the tools I have.

We value most what we make.

Building Modern Ruins

modern or ancient?

'06 Bridgton Academy project by North Star Stoneworks

Although I devote most of this blog to brick oven topics, as a landscape designer, I enjoy seeing the larger picture when planning a brick oven on any location.

The photo to the left was taken in Pompeii, Italy and could easily be a 'modern' courtyard.  The above ruin was designed and created by me for the hillside and campus of Bridgton Academy in Maine.

I was asked to design for the center of a 200 year-old campus in a space directly in front of a brand-new humanities building.  In this case, I created a circular stone remnant tower base (later to be referred to as an 'outdoor classroom' for the sake of purposing it).  With a steep hillside to the east, I built in a breach in the wall where a dry stream bed of river stone snaked down the hill, accented with boulders (as any stream would be).


Applying the same technique of inventing a fictional history that is suited to a particular site, I look for reference points when planning brick ovens.  What is the vernacular of the place.  The brick oven itself is an historic cooking device.  However, the appearance of them changes with region and culture. 

Certainly, if I was asked to recreate a cultural model, I would look to visual references and proceed, but finding the unique blend of form and materials in any given situation makes my work as a mason especially interesting.

Brick Oven Specs #2

unfinished oven showing chimney in front

Universally, brick ovens have their flues in front of the chamber. This allows the heating fire to move across the dome roof before exiting thus depositing BTUs in the roof and walls of the oven.  It also means that when a door is placed over the oven chamber, the heat is trapped inside.

Brick oven mouths (the opening into the brick oven) work best when they conform to a proportion of 1:1.6 or 11" high and 18" wide.  The mouth can be a bit wider but the limiting the height of the mouth prevents too much exchange of cold outside air during firing and baking.

no chimney (exhaust hood covers oven)

outdoor clay oven w/o flue

Chimney height is entirely optional.  Some ovens have no chimney or flue and the smoke exits directly out the front.  An outdoor oven might have a three foot chimney which prevents smoke from spilling across the face of the oven (except when the fire is excessively stoked).

Indoor oven with first flue arch

Indoor ovens need to be guaranteed not to spill smoke into the living space.  Tall chimneys create a natural upward draft.  A chimney of 12 feet or greater will draw the smoke and flue gases up the chimney sufficiently to prevent smoke in the room.  Other factors, such as the ridge of the roof and horizontal angle of the exiting chimney will alter this equation.  Most chimney installers have this equation, but it is approximately 3 feet of chimney height negates 1 foot of horizontal angle.  This means that if you angle the flue of the oven at a 45 degree angle for six feet you need 9 feet of height to negate the loss in draft (45 degrees is halfway to horizontal so the equation is based on a net-3 feet multiplied by 3= 9 feet).




Math, that high-school nemesis, rears its useful head for masons.

Brick Oven Slaves

3712 years ago the Greeks had portable ovens, presumably so that the rulers could have fresh baked bread on their Mediterranean cruises (You thought Club Med was original).
These were very likely shlepped around by slaves (possibly my ancestors).
Nevertheless, it was a good idea.  It still is.
A portable oven provides flexibility of location that even a lowly middle-class person would enjoy.
Whereas wealthy people wouldn't think of towing a small oven to a friend's house for a party, we could (and I do) easily bring my oven to places near and far for the joy of cooking ensemble.
Surely, I am not a slave to the oven; it however is my servant. 

I recently gave my portable oven an upgrade, adding a faux-slate roof and a limed oak trim board.

Invitational Brick Oven Seminar

True Brick Ovens’ David Neufeld invites attendees of the 2012 Northern New England Home and Garden Show to experience brick oven baking first-hand.

The First Invitational Brick Oven Baking Seminar will take place each of the three days (May 18, 19, 20) at 2pm in front of Expo One at the Fryeburg Fairgrounds in Fryeburg, Maine.

In order to participate, you are asked to sign up via the True Brick Ovens website: www.truebrickovens.com.  A maximum of ten participating bakers (that may include you) may then bring loaves, risen dough, or pies to place in the pre-heated brick oven on site.  You may then take home your product, gobble it up immediately, or share it with other bakers in the daily session (or all of the above).

 

I'm an advocate of community brick ovens and through these invitational events, I hope to get communities, neighbors, and friends to 'go in' together on brick ovens so that they can experience the social aspect of baking.

What it would be like if you gathered with fellow bakers once a week and went home with fresh baked goods?

Arrive with six loaves of your bread and go home with some of others' bread or a pie and a stack of pitas.

Add this to a farmer's market and, except for the clothing styles, the bad hygiene, and the plague, it would be just like medieval times.

Factory Brick Ovens

Whenever a traditional practice gains enough popularity, a factory is built to mass-produce the commodity.  This drives down the price and drives down the quality.  I'm wearing clothing from that result.  Much of the food we eat is grown on mega-farms.
But as a mason, the adjacent photo puts me off.  Even among masons, many buy and install cast-refractory inserts for ovens and fireplaces, so that they can increase their production-speed.  Volume wins over quality.

Are we meant to use only factory-made products?
We travel to other, often older, cultures to see the 'real thing'.  We occasionally purchase an original work of craftsmanship.  The slow-food movement is a re-imagining of our relationship to the food we eat.

A hand-crafted brick oven will not only last for generations, but give your family an experience of tradition.

True Brick Ovens builds mason-crafted brick ovens throughout the Northeast US.  We love what we do.

Brick Oven Mosaics

There are many ways to individualize a brick oven. We each have an image of the brick oven of our dreams: Some of stone, some red brick, some stucco.  Each may be connected to places we have visited or the first brick oven we 'met'.
Then there is the 'artistic' additions that match our personality, business image, or some trace medium that we want to splice onto our oven.
Occasionally, I've offered to create frescoes on the stucco of the ovens I build (I have a sculpture/painting background).
This oven, a dome which I built for a chef and caterer, has been enhanced and made personal by the pebble, sea glass, and mirror mosaic on the band of stucco over the dome. Mosaics have been used on some of the most splendid brick ovens all over Europe (and then in the US).
The arch and keystone details were my concept and were designed with the customer's input and approval.

Bread Baking For Welders

There are many skills which I would recommend having when building a brick oven: Certainly some experience baking bread or pizza. Perhaps some masonry experience or construction background.
I ran across this oven in upstate New York.
The sheer size of it is impressive (read 'scary'). The trailer and the multiple layers of steel tubing, recycled oil tanks, levers, chains, etc., weigh many tons.
The complexity of the chambers, baffles, and swing-up chimney make this 'oven' a true Rube Goldberg invention.
The owner told me it cooks everything great.
I can only say, "If welding is what you do, hey, weld away. Bread has been baked in stranger devices, though none come to mind at present."

Indoor Brick Oven Finish

Brick ovens that are part of an everyday kitchen get used a lot.
This oven, a project that was coordinated with the complete gutting and renovation of a kitchen, has actually permitted the family to cook for weeks while the high-end gas range that failed following installation is replaced.
Sometimes the 'old way' is the most reliable. One beautiful firing and three days of cooking.

oven prior to enclosure

A year later (December 2012) I have built more indoor brick ovens.  The two pictured show that one required the 'bump-out' or exterior placement of the mass of the oven and the other accommodated for the entire oven within the living space.

In all cases it allowed far more frequency of use than an outdoor oven in New England would normally permit.

Exactly one year ago I posted the above.  Today I added 'Brick Oven Elegance' showing another completed indoor brick oven.  I continue to encourage people in climates where rain, snow, bugs, and...let see... and drones may inhibit the use of an outdoor brick oven to consider the sheltered or indoor brick oven option.

Brick Oven Specs #1

The materials from which a wood-fired oven is constructed vary greatly.  Brick oven materials are more specific.
The thermal requirements of a brick oven point to quality materials.  The oven is constructed of firebrick with a balanced heat-coefficient.  The equation to the below says it all...

Q = heat flow in input or lost heat flow , J/s = W

h = heat transfer coefficient, W/(m²K)

A = heat transfer surface area, m²

= difference in temperature between the solid surface and surrounding fluid area, K

Right.   The long and short of it is: you want a material that absorbs the heat of the fire sufficiently well to radiate that heat for long periods of time so that the oven environment remains an even temperature. In this equation, the surrounding air is considered the 'fluid'.  If the difference between the temperature of the brick and the internal temperature of the oven are close to even, an ideal material has been used.
Porous bricks do not absorb heat well.  Very dense bricks absorb heat too quickly. Some materials transfer heat to the exterior of the oven. Others just heat up on the interior surface.  That said, you can make pizza in the most rudimentary oven because the 'live fire' is doing half the work. The real work of the brick oven begins after the fire is out.  The residual heat on my ovens last for about 30 hours. The hours you take to heat the brick of the oven is rewarded by 30 hours of cooking temperatures (these temps decline slowly giving you a baking environment suitable for a dozen types of foods)

Standard duty fire brick is well matched to brick oven construction.  They are inexpensive enough to justify using them over the more fragile and less efficient red brick one might pick up for free.  They are also exponentially (big mathematical word again)  more durable than cob.

For residential ovens and ovens not used on a daily basis, a single thickness floor is adequate but for professionals, a double layer of floor bricks is recommended.  Modular fire brick in the U.S. is 9" x 4.5" x 2.25" which makes laying them in herringbone or any other symmetrical pattern straightforward.  Some masonry yards supply fire brick that are not modular. Don't use them.
I've noticed that in other parts of the world fire bricks are commonly available in much bigger dimensions. But then I don't live there.
Arch bricks and fire brick tiles are also available but they are pricey.  An entire brick oven can be beautifully built using the one standard modular brick size.

The domes of my ovens are 4.5" thick. This gives me two dome segments per brick.  Standard duty fire brick cuts easily with diamond blades.

The next posts will address mortar, proportional dimensions of mouth, throat and door openings and heights of chimneys.  In the meantime keep this equation in mind (V= volume):