The recipe for Sumerian mud bricks included a mixture of riverbank clay and water, along with reeds, straw or dung. The straw or reeds held the brick together. To keep the bricks in place and seal them, the Sumerians used a more watery version of the mud-brick mix as a mortar and as a plaster.
Early in Sumerian brick-making history, bricks were shaped by hand, and they were rounded. Later, they began to use brick molds made from wood, which were filled with the mud mixture to form the bricks. As time went on, bricks that looked like loaves of bread began to be made.
To complete the mud bricks, the Sumerians used sunlight, leaving the bricks out in the sun to dry them. In fact, a Sumerian month between May and June was called "The Brick-Mold," and it was considered the best time to make bricks.
A fired brick is baked at a high temperature. Ingredients for fired bricks included clay and ingredients to make glazes, which have been found in blue, yellow and black.
Like mud bricks, fired bricks were shaped with brick molds. For firing the bricks, the Sumerians needed materials to make a kiln -- an oven able to withstand high temperatures -- and wood to heat the kilns. This was among the first cultures known to make kilns.
Bitumen is a black, petroleum-based substance that is sticky, has a strong smell and is used in asphalt. The Sumerians used for the gaps between bricks, along with well as straw or reeds. Bitumen helped preserve the mud bricks, as they were easily eroded by moisture.