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This document was written for the benefit of people, especially historical re-enactors, who are interested in making and baking in a medieval style bake oven. This practical knowledge was gained during the author's participation in the Society for Creative Anachronism. The companion photo gallery helps illustrate many of the construction details.

This document is provided as is without any express or implied warranties. While every effort has been taken to ensure the accuracy of the information contained, the author assumes no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein.

Permission is granted to make and distribute verbatim copies of this document for non-commercial private research purposes provided the copyright notice and this permission notice are preserved on all copies. Mirroring of this article is only permitted by prior arrangement with the author.

Building and Using a Medieval-Style Hemispherical Bake Oven

© 1999 Carolyn Priest-Dorman


This document is not a directive on the only way to build a medieval oven. This document simply describes how we in Buðgarðr build the particular style of mud bake oven that we cook in for ten days at the Pennsic War each year. There are already two generations' worth of heirs to our design being used at Pennsic, as well as other related designs descended from the same ancient and venerable ancestors, Hansel and Gretel; feel free to design one that works for you, too.

Our oven is an unvented hemispherical structure with one door, built on a small wood-framed platform; the oven causes no fire hazard to turf because of the dirt-filled, brick-faced platform. Our oven is based on one from the 12th century found in an excavation at York, England (i.e., Norman period), although it is similar to earlier Viking Age ones. The original was made out of wickerwork and completely covered inside and out with daub. However, in order to make a wickerwork oven you need a three-week period before use in order to ensure that it is dried and fired correctly. Needless to say, we don't have that kind of time at Pennsic, so we make do with a different armature.

The Buðgarðr encampment is grateful to Dave Cooper for having granted us permission year after year to build this oven. We also thank Goodwife Marian of Edwinstowe (Marian Walke) for her having so generously shared with us the knowledge she gained about building and using a brick oven while proprietoress of the Sated Tyger Inn at Pennsic. Certain of the techniques we use are somewhat different from hers, but we could never have entered onto this path without her guidance. We also thank the Smoky Baron, Durr al-Jabal al-Makhfi (Dale Walter), for instilling in us a firm awareness of the fire safety issues involved, and Lady Oksana Goncharova (Susan Calafrancesco) for teaching us how to handle daub properly.

Tools and Supplies

To build this oven and platform you will need the following tools.

You will also need the following materials.

On site you'll need to procure the following.

Choosing a Site for the Oven

Give some careful advance thought to where you want to locate the oven. A poorly placed camp oven will sit unused, while a well-placed one can be used freely and safely in all weathers.

If your site has fire restrictions then you'll need to provide a large safe zone around the oven area. You'll also want it convenient to the kitchen and in an area where the cook won't feel unduly isolated while overseeing the baking. Take into account the layout of the kitchen, the firewood supply, and the traffic patterns in your encampment. Also pay heed to the site's prevailing weather.

You will also need to decide in which direction the door of the oven should face. When we have camped on the Serengerddi at Pennsic (a flat, windswept area), we have found it's good to have the door to the southwest: the prevailing northwesterly winds will take away the heat when you're working in front of the door, and neither the northwesterly nor southerly rains can go directly in the door.

Making the Platform

First, saw the boards. Cut the two pieces of lumber into four pieces so that they fit together into a square framework. As long as they fit together fairly neatly, it doesn't matter what style of joints you use, although I don't think I'd enjoy stumbling over mortise and tenon joints.

Then set up the frame where you want your oven to be situated. Reinforce the frame in some manner so it doesn't fall apart when you fill it with dirt. (We tie a rope around the framework and set pegs around it.) Fill the frame with dirt.

Level and face the dirt with one layer of bricks. Pay attention that the bricks underneath the center of the area are nice and smooth; you'll be baking on them. You don't have to face the entire platform if you're short on bricks, but make sure the area of the oven is entirely faced. Make sure you tramp down the dirt and bricks evenly.

Set up the iron straps so they are more or less evenly spaced. Put bricks over the ends of each strap to anchor it.

Starting with the anchor bricks you just put down, stack the bricks in a beehive around the straps. Don't worry that you're not making a perfect hemisphere: it's a lot easier to make a basket into a hemisphere than it is to stack bricks into one! Just do the best you can. If you pile the bricks so they sit on their largest planes (as if building a house), you'll need more bricks but will have an oven that holds the heat better due to the thickness of the walls. You can also pile bricks on their sides (narrow planes); it's slightly less stable but a good daub job will take care of the stability problem. Either way works; choose what is best for your needs.

Make sure you leave a rectangular area for a door. Do not leave any other large hole in the roof or anywhere in the wall (chinks are okay, as you'll be plugging these with daub). We sometimes put an iron strap across the lintel of the doorway to help reinforce it.

Build the daub pit. This job can be done concurrently with the other tasks if you have enough hands. Using logs of firewood, outline a hollow square or rectangle about 3'x3'. Make sure you select a flat area for this, otherwise you will become exhausted well before you tread out enough daub. Drape the cheap plastic sheeting in that and put another line of firewood down to hold the sheeting in place. This is your daub pit; two can use it at once if they're friendly and stay near opposite corners.

Chop the straw. People who want to help but are squeamish about getting dirty can often be coaxed to help in this fashion. Give 'em a small axe and tell them to reduce about a quarter to a third of the bale to straws less than 3" long. Keep 'em around in case you need more straw.

Mix the daub. Put in about 4 buckets of clay. Add in several handfuls of the chopped straw. On top of that add about half a bucket of sand. Drizzle in a bunch of water, strip to the thighs, and start squishing with your naked feet. Be sure to let everyone have a turn that wants to, because this is one of the fun parts; sing, dance, make jokes, and pretend you're a little child again. This is also the part we jokingly call "naked Laurel mudwrestling." The daub is ready to use when it is consistent, cohesive, and capable of holding a rough shape when squeezed in the hand. You don't want it too clay-like, as it has to be loose enough to ooze into chinks easily.

Daub the daub: take up a really big handful and splat it onto the bricks. Use some force, which will help drive the clay into the chinks. Fill the biggest chinks first, then begin to cover the whole oven more or less evenly. When you've got it covered, wet your hands and smooth it well; this helps to fill in the little tiny chinks and airholes.

Firing the Oven

First, observe good fire safety: make sure you're wearing clothing that is natural fibers and that does not trail unduly. Then light a big fire of dry wood in the oven. As it heats the oven will start to steam and leak. There is a visual difference between the two phenomena. Leaks are where plumes of smoke come out, usually from tiny yet visible smokeholes. Steam is more diffuse, emanating from the surface in a foglike swirl.

Add more clay to the areas that leak, but ignore the areas that are randomly steaming. When you get tired of patching, build the fire up. Save half a pail of daub, covered and damp, to use for patching later in the week. Try to keep the fire good and hot for a couple of hours--longer if possible. You can use it to cook covered dishes on this first day, but it will make any baked goods taste nasty, so be patient until the next day.

While you are firing the oven, if you like you can make a removable door to cover the opening of the oven. Sometimes we use a thick slab of wood with a handle nailed on the back side. Sometimes we cover the inside surface of this door with metal (a disposable aluminum baking sheet), and sometimes we just soak the wood in water. Usually we just chink up the doorway with extra bricks.

Cooking in an Oven

When the morrow rolls around, it's time to do some proper baking. Fire up the oven for a while (half an hour or more) while you prepare your food. Then scrape out all the fire and coals. We scrape directly into that wok I mentioned before. Now you'll need to figure out how hot your oven is.

We learned the basics of temperature estimation from Goodwife Marian's advice. You might want to substitute for the word "rhinoceros" some other four-syllable word or phrase that wouldn't be inappropriate if you intoned it in the middle of your camp, e.g., "in my armour" or "Serengerddi." Or, you can intone silently. Controlled experimentation at home has revealed that my personal tolerance at 350 degrees Fahrenheit is about 12 rhinoceroses. I usually heat up the oven to about 2 or 3 rhinoceroses for quickbreads or pastries and then work down to bread baking.

If your oven is not hot enough yet, dump your fire back in and keep heating. If it's hot enough, then make sure the floor of the oven is clear and put in your goods. When we bake bread we do it on aluminum sheets, so we don't usually mop the floor of the oven first. (Some year I'm going to try using a soapstone pizza stone as the floor of the oven.) But even if you don't mop, it's still necessary to clear out all the coals because they can cause uneven heating.

Try not to open your oven too often while it's cooking. If you use the brick method for closing the opening, then please remember always to wear hand protection: those bricks are very hot!

Sometimes we heat things in the oven while there is still a fire inside it. This is an especially good method to heat a potful of water first thing in the morning, when you may want a hot beverage long before the oven is hot enough to cook your pasties.

Living with an Oven

In order to build and keep a good cooking fire in your oven you'll need to reserve for it your dryest hardwoods. Keep some dry, clean tinder around too. Don't use wax, fire bricks, or fire starters in the oven, because they put nasty fumes and chemicals inside the oven. Ditto anything with creosote or pressure-treated lumber. If you have a pipe or something to blow on the fire with, that sometimes helps in the kindling phase.

In order to fit it inside the oven, you will also need to split your oven wood much more finely than you do your firepit wood. Give this job to a Boy Scout, adolescent, or similarly energetic soul, as long as he or she is safe with a chopping axe, and you'll never lack for wood. Two young men who frequent our encampment vie to be the one whose turn it is to split the oven wood.

As it dries, your oven will develop a network of cracks. It may even need some more spot patching from time to time during the week. A little loving maintenance of this sort will keep it in good shape, so don't spare the daub. If it's been fired well, your oven shouldn't have any problem holding its shape in the rain. But if you keep a fire in it during rain, it will stay happier longer.

With a fire in it, the top of an oven makes a good warm place for various camp purposes. We've used the top of our oven as an incubator for yoghurt cultures, sourdough crocks, and pans of yeasted breads. It also makes a dandy place to dry towels, soak leather, soften wax, or contribute to any of a myriad other little campsite projects.

Breaking Down the Oven

It is an inevitable fact of life that temporary ovens have to be removed sooner or later. We usually take ours apart by having someone whack it solidly on the top with a sledgehammer, once. This breaks a good deal of the clay and doesn't usually damage any of the bricks. Then the debris can be picked apart, the bricks and straps saved for another time, and the clay and dirt removed in the manner specified by your hosts.

Over the years we have lost one or two bricks to heat damage, but overall there has been absolutely no problem with using regular bricks. This is true even though we have heated the oven well beyond cooking temperature, or, as we fondly say, "no rhinoceroses!"

May your bread never burn!

Don't forget to visit the oven photo gallery!

This page was created on 8 April 1999 and last updated on 8 May 1999.

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