SC - Building ovens

[Martin G. Diehl]

Erin Kenny wrote:
> 
> His Grace Cariadoc mentioned:
> 
> > We've never built an oven, although I know other people who 
> > have.   Other people in the encampment have done spit roasting.
> 
> Is there anyone out there who has built an oven at something like
> Pennsic?  My husband and our friends would like to build one in the
> first week so that we can experiment with some baking.
> 
> 
> Claricia Nyetgale
> Canton of Caldrithig
> Barony of Skraeling Althing
> Ealdormere  (still mostly in the Middle Kingdom)

Greetings to the Esteemed Cooks of the SCA,

I have thought about this, but not yet tested the design.  My 
thoughts go as follows.

1. Size: What is the size of the largest item to be cooked?  Round 
   up to the next larger 4" in both the side to side and front to 
   back dimensions.

2. Materials: 
   A. 2 pieces of flagstone whose dimensions are at least 1 foot 
      larger than both of the dimensions determined by step 1
   B. Fire brick -- this is a refractory material used to line 
      boilers and fireplaces.  In order to determine the number to 
      buy, you need, first get the sum of the sides of the 
      rectangle needed by step 1.  Divide that length by 8" and 
      round up to the next integer.  That is the number of bricks 
      per course (1 layer of bricks).  Multiply that number by the 
      height of the oven and divide by 2.  You will also need 
      enough bricks to cover the base of the oven; to get that 
      count, use the outside dimensions of the oven to compute 
      the area (side to side width times front to back depth) 
      divide by 32 and round up to the next integer.
   C. Heavy insulated gloves
   D. Fireplace shovel

3. Construction:
   A. Clear and level and area larger than the larger piece of 
      flagstone.  The outside of the oven should get very hot.  
      Think of fire safety and children when planning your 
      campsite, cooking area and oven.
   B. Lay out one layer of bricks with the 4" by 8" face showing 
      (not on edge) in an ashlar pattern on one of the pieces of 
      flagstone.  (An ashlar pattern is what you usually see on 
      the face of a brickwork wall.  Do not leave any gaps.
   C. Build up the three of the sides in another ashlar pattern to 
      the height needed.  Arrange the pattern so that at the corners, 
      the overlap changes at each course.  This improves stability.  
      The open side is to provide access to the cooking area.  It 
      is possible to create a place to hang a cooking grille by 
      laying some bricks at right angles to the wall.  A more 
      detailed explanation will have to wait until I can test this 
      and draw some diagrams.  This might also increase the interior 
      size and, correspondingly, the brick count.  Aside from the 
      open face, do not leave any gaps.

4. Heating: Load the cooking area with firewood or charcoal.  Light 
   fuel and stack the remaining bricks to close the opening.  In 
   order to allow air to enter, you must omit one brick from the 
   first course.  Finally, cover the top with the second piece of 
   flagstone, but leave an opening to vent the smoke.  Allow enough 
   time for the fire to burn down.

5. Cooking:
   A. While the oven is heating, prepare the food to be cooked
   B. Use the gloves to remove the last wall you built.
   C. Clear the ashes.  The fire pit is a good place for them and 
      could be used for other cooking.
   D. Food into oven
   E. Close up the open face and cap so that there is no airflow.
   F. Cooking time.  That's a tough question -- experiment is my 
      advice.

Some additional thoughts:
   1. making it larger will allow more fuel and therefore longer 
      cooking time
   2. at first, use it items that are not time critical -- bread 
      for example
   3. it could also be used as a barbecue pit if the grille and 
      oven dimensions are compatible
   4. try it some weekend before an event
   5. the materials are heavy
   6. you might be able to close the top with bricks by 
      cantilevering or creating an arch, but it's less stable and 
      beyond the scope of this note.  
   7. you might want to use double thick walls to retain additional 
      heat and lengthen cooking time
   8. structural stability is a concern
   9. meats like pork should not be used until you are sure that 
      it retains enough heat to finish the cooking.
  10. could use common (red clay) brick in place of fire brick
  11. common brick are 2" by 4" by 8"; firebrick are slightly larger: 
      2.5" by 4" by 9" -- this difference might affect the size of 
      the pieces of flagstone
  12. remember that the ability to effectively cook depends on how 
      hot the oven is and how long it stays hot -- using it in 
      winter or a rainstorm will give different results from using 
      it in summer
  13. once you start to use it, you cannot "add" heat except by 
      starting another fire in it

As I said, I've been thinking about this.  I'm going to have to 
follow my own advice and build a test oven.  But not until after 
PENNSIC XXVI.

Please let me know what you think.

I am, 
Vinchenzio Martinus di Mazza, 
In Service to the Dream

- -- 
Martin G. Diehl

Sig under construction
Home page not even started, PENNSIC comes^H^H^H^H^Hcame first!