Brick Oven Dome Building, Part 3

There is a point in building the dome when gravity prevents mortaring bricks without a form. Foam insulation was cut in curved wedges to support the succeeding chains of bricks.  This form rests on pieces that can be removed later through the oven mouth. The maximum size of each piece is determined by the width and height of the mouth.

As building progresses, wood wedges are used to tilt the bricks at the appropriate angle so that the dome shape conforms to the desired height. Once the wedges are removed the cavities are filled with refractory mortar and the wedges reused on the upper courses.  Bricks are cut at increasingly sharper angles and decreasing widths so that the radius of the chain is followed.

The goal at the top of the dome is to close the remaining space with a final key stone that applies outward and downward pressure on all the bricks.
This is what makes the dome shape stable as it expands and contracts in firing.