Masonry Magazine August 1999 Page. 35
The Cooking Fire Place
The difference in New England and in other colder climates was that the ovens, instead of being outdoors and built of stone or adobe, were usually built inside and built with brick and usually associated with cooking fireplaces. Beyond that there was great variety. I have poked my head into many old ovens and read what I could find on the subject and came to the conclusion that building a masonry oven was an "imprecise science" in the words of Peter Rose who wrote one of the best articles, "Baking in a Beehive" published in 1985 in Americana. Apparently masonry ovens are fairly forgiving and/or the cooks didn't complain much and were able to adjust to what must have been very different firing procedures and firing times from one oven to the next.
The ovens discussed here are called "black ovens" which means the fire is in the same oven chamber where the food is cooked. Smaller ovens are "periodic" ovens in that after the oven is hot and the fire out, the ashes are swept out and the oven floor damp mopped before the food is cooked. Larger commercial ovens might be fired continuously with the fire pushed to one side or the back to make room for the food. There are "white ovens" which are heated by a fire below the oven or by flue gasses in passageways around the oven as in some masonry heaters, but white ovens are difficult to build so that they get hot enough and are not very common.
The "rules" for black ovens as well as I can figure out are: The shape of the oven is ideally like that of an Eskimo igloo - semi-spherical with a tunnel entrance although many ovens are arched vaults or even square.
The oven has to be at least 16" in diameter inside to be useful.
The flue, if there is one, is just inside the oven door or entrance and must be at least 67% as high as the top of the dome of the oven.
The walls must not be too thin (the oven will not stay hot very long) nor too thick (the oven will take too long to get hot). I figure the walls should be about 8" thick and kept at least 2" away from combustible materials to comply with modern building codes for fireplace fireboxes. If the oven walls are within a more massive chimney structure, I insulate between the 8" oven walls and the rest of the masonry. Otherwise the oven never heats up.
Early American ovens built before 1760 were usually built into the back of big cooking fireplaces. The one shown below, built about 1720 outside a Bucks County, PA roadhouse. It is about six feet in diameter with the entrance in the back of a twelve foot wide fireplace on the other side of the wall. Notice the "squirrel tail" or "Mohawk" flue passageway over the top of the oven and venting into the fireplace just above the oven entrance which was probably an ingenious way to get the oven to heat more evenly and draw better.
This style was typical in Colonial America. After about 1760 ovens were built to one side of the cooking fireplace more like the one at the top of the page, rather than in the fireback, probably because so many cooks caught their hair or clothing on fire reaching over the fire to use the oven.
Masonry ovens have been built in American homes since the first colonists landed in New England in the 17th century and before that when the Spanish settled in Florida and the Southwest in the 16th century. Surprisingly there weren't many differences between the ovens built in New England and the ones the Spanish built because oven traditions date back much farther - to at least Roman times.
MASONRY-JULY/AUGUST, 1999 35