Turtlerock Masonry Heat
ELMORE MTN BREAD FARM AND SPARROW BREAD AND BUTTER FARM BLUE OVEN BAKERY VERGENNES LAUNDRY
IMAGERY
HARDWARE
About Us

Ram's head wind burst.

About our ovens.

Wood fired bake ovens have many forms, and have different cultural and regional expressions based on production needs, available materials, and style of bread produced.
Our larger commercial ovens are typically called “black” ovens. This means that they are fired inside the baking chamber. The fired is allowed to burn out, the ashes removed, and then the oven rests dormant for a period of between 4-24 hours before actual baking starts. This dormant period is important in that it allows the energy inside the oven to even out, creating a normalized baking environment across the hearth and vault. Keeping a low ceiling with a vaulted arch is great for bread production, as it keeps the top of the bread closer to the radiating masonry above (for even baking in relation to the hearth, on which the bread sits) and just as importantly because it keeps the steam close to the bread, aiding in the proper formation of the crust. These barrel vaulted heat retention black ovens are excellent for the production baker.
The barrel vaulted oven style can be modified for different sizes and formats, and works well for many applications, including pizza and general baking. However, it’s recommended that a dome style oven be built for pizza specific applications, such as a restaurant or back yard where the user has no or minimal interest in bread. We are also able to build either of the styles on trailers for mobile use.


First pizza bake at EMB.

Energy.

Energy is an important concept when it comes to wood fired bake ovens. Combustion releases the stored energy available in wood. The masonry mass in the bake oven absorbs that energy as it is released- a process which hopefully minimizes energy lost up the chimney stack. Raw bread dough is set upon the hearth, consuming the stored energy as it bakes. The bread is removed from the oven, and the energy stored in the masonry depths re-charges the surface temperatures of the hearth and vault. The insulation around the oven prevents energy loss from any other source than the baking of the bread.
A production bake oven should be designed so that it becomes a predictable user of energy. Since there is no thermostatic control dial on a wood fired oven, the baker needs to know how much fuel and firing time is required to store an amount of energy into an oven to bake an amount of bread for the next bake day. A crucial issue is ensuring the right balance of mass and insulation to provide energy for timely bakes at the end of the baking day. To accomplish this, the mass must be sufficiently soaked to the depths, but also fired in a way to promote deep soaking as opposed to high surface temperatures. If an oven is fired too hot too fast, the high early hearth temperatures may need to be moderated before baking. Also, when an oven is fired as such there may not be sufficient stored energy for use at the end of the bake day.
Getting an oven soaked through and through with energy is the key to consistent baking success and predictable baking conditions. Often it may take a baker a while to learn just how to fire a new oven; however it is critical for an efficiently minded operation to have an oven do what it is supposed to do consistently. The oven should have the capacity to hold more energy than required on even a big bake day, so that there is always some latent heat in the mass, which then promotes ease in the next firing by reducing the duration and fuel consumed. The oven should also be allowed to rest between firing and baking so that the temperatures even up through the mass. A good oven should bake evenly and have no hot spots. The bread should not require turning while baking, but emerge from the baking chamber in the reverse order as it was put in, and have even color, crust, and crumb.

Materials.


Original frogged brick from ruins of Guastavino kiln,
North Carolina.
The materials used in masonry oven construction should reflect the duty and use patterns that are intended. In general, materials of the best quality should be used whenever possible and as much as budget allows. This is especially important with respect to commercial ovens for artisan bakers, where the demands on the oven are great and the price of oven failure high. With proper materials specification certain “x-factors” can be more or less ruled out.
Ovens can be labor intensive to build, and also tricky to modify once completed. For this reason attention must be paid to materials in all phases, especially the refractories for the baking chamber. In this area we recommend the best quality/duty firebrick, tiles, castable, and mortars. On most oven projects, this means working with non-local refractories suppliers to get the proper materials and having those materials ordered and shipped to the building site. The facing veneer materials can be sourced locally, as well as masonry supply for the foundation and chimney.
Insulation is of utmost importance to oven performance. There are undeniable boosts to heat retention characteristics, even baking, fuel use efficiency, duration of baking “window” etc when insulation is upgraded from the North American standard of “a few bags of vermiculite” to insulations of better quality and in suitable amounts. Currently we employ a “sandwich” combining ceramic blanket and rock wool. Foamglas is also used. The hearth is generally the part of the oven most abused, but also the part most easily replaced when worn, whether in whole or partial sections. We use larger firebrick tiles for hearths due to smooth surface texture and ease of removal and replacement.
Mild steel is generally acceptable for harnessing details and door frames. Certain locations may require stainless steel for best performance and to prevent warping and/or corrosion. Masonry oven veneers are open to lots of possibilities including brick, stone, tile, plasters, stucco, concrete, steel, and any combination of those elements.

Capacity.


Baking chamber at Bread and Butter Farm.
The baking capacity of a wood fired oven is reflected in the thickness of the masonry mass, the amount and quality of insulation around the oven core, and the size of the baking hearth. These factors, when combined, create an “economy of scale”- larger ovens with ample mass and insulation tend to require proportionately less firing when kept in regular operation and when left with some embodied energy at the end of the bake day. Efficiency increases with oven size.
At the time of this writing, the larger six foot by nine foot hearth size commercial ovens have stayed ahead of the production curve for the bakers that use them. An oven that size will handle a seven hundred loaf bake day and still maintain respectable temperatures in the deep hearth and vault thermocouple temperature sensors. It is possible to bake and fire the oven for use the next bake day, and so keep the oven producing 700 plus loaves daily. It’s more common for the smaller one-two baker artisan operations to bake every other day.
Maximizing the oven’s output on bake day requires a properly fired and well soaked oven, so that there is energy left at the end of the bake day for the final oven loads to bake in a reasonable time. This may mean higher early hearth and vault temperatures. Making use of the oven at this higher temperature phase is key to keeping production levels high. It’s a good time for loaves that can handle temperatures better, such as focaccia or heavy rye breads. The massive heat retention ovens will always have a temperature curve, so choosing to bake breads that follow the curve of the oven will result in greater production capacity.

Ergonomics.

Good design should be based on studying the movements of bakers as they work. It should keep a focus on reducing unnecessary actions and putting the relevant features of the oven in excellent relation to the body and oven tooling. As such, it is possible to build ovens that make for a shorter bake day (with same or better production) and also reduce baker fatigue from repetitive motion.
Our larger ovens (and some smaller) employ wide door systems that allow loading of the raw dough with two or three “straight-forward, straight-back” passes into the backing chamber. The peel does not need to be used at angles and bread does not need to be dug in and out of corners to maximize hearth space. These wide door systems also allow bread to be loaded and unloaded with automatic peels.
Hearth heights should be set to the approximate elbow height of the intended baker or floor levels adjusted to gain or reduce to appropriate height.
When possible baking doors should not require movement other than that of the peels entering and exiting the oven for operation.
The larger heat retention black ovens maintain a very even temperature environment. This allows the bread to bake evenly and without needing to be turned or relocated to a hotter/cooler place in the oven during the middle of a bake. Reduction in baker effort is an ergonomic benefit.
Wood storage may be incorporated into the foundation design or at another area in the bakery.

Efficiency.

Efficiency in baking should be considered as the sum of all the facets of a bakery operation, and in this the bake oven itself plays a critical role. The oven must perform well from a technical perspective in the way it absorbs and stores energy released from the burning of wood fuel. The oven must retain this energy by properly combining mass and insulation. The oven must bake bread at even temperatures and in a repeatable way. The oven must be easy for the baker to fire and use. The oven should work with the baker and at no point should the baker feel frustrated with the performance of the oven but instead see it as a partner in a reciprocal relationship. The oven should be a known, predictable device, free of speculation and mystery.

Duty.

We strive to build our ovens very heavy duty, with an eye towards long term use and a goal of low-maintenance. We start with a solid foundation and a reinforced poured solid concrete hearth slab, then start the oven system using a sub-hearth insulation with high compressive strength, avoiding the failures of slabs suspended from rebar ends and the hanging, low performance vermi-crete hearth insulation fixtures of past designs. From a stable hearth platform oven sidewalls are built, with an eye kept towards managing expansion at the juncture between the sidewalls and hearth tiles. A heavy duty steel harness is attached at the top of the sidewalls (at the level of the angle cut “springer” bricks) to contain the outward thrust of the vault, which is then installed over a temporary wooden centering form. A long lintel made of castable refractory cement enables the wide oven front. All materials (brick, castable, tiles, harness, door system, mortars) are specified at the highest practical duty level for their intended use.

Style.

Aesthetics reasonably play a smaller role than performance criterium for most bakers. A simple veneer is often all that is required or expected for most bakeries, whether the bakery is a retail location or not. However, some bakers spend a considerable part of their lives tending to their ovens, and so a more detailed or personalized oven front face becomes part of the design plan. We strive to meet our customers style and retail location aesthetics.

New and better life for an old ammo box.


If you have any questions please contact me and I’ll be happy to chat with you.

CRAFT NOT DEAD.

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