Adobe bricks are made of native soil combined with some kind of organic material. In New Mexico, soils known as “adobe soils” are not well suited to brick making. They generally contain far too much clay and tend to shrink and crack severely as they dry. At the same time, if a soil is too sandy, adobe bricks will erode easily in wet weather. The right mixture is about 75% sand, 15% clay and 10% silt, which is a fine dirt containing very small particles of eroded rock. When the correct soil is located, brick making can begin.
There are several steps in making adobe bricks. First, the soil must be mixed with water until it becomes quite thick. Next straw, hay or some other organic material is added to strengthen the mixture. Third, the brick mold should be doused in water so the mixture will not stick to the sides and then placed over the mixture. Fourth the mold should be filled completely and the mixture compacted thoroughly, and then allowed to dry for about an hour. Lastly, the bricks should be transported to a drying area where they can lay undisturbed for one to ten days, depending upon the weather and the humidity. At the location, the bricks should be removed from the mold. Bricks can be stacked, but side-by-side drying is usually faster. As the bricks dry, they will become stronger and stronger. An average adobe brick is approximately 10” x 14” but size may vary according to the availability of materials and the intended use for the bricks.
In the MRM Collection: Adobe Brick Mold
This is an adobe mold made of cottonwood. It is 19” long, 9” wide (measured along the bottom of the mold) and 5” deep. Four holes are drilled in the bottom. Carved handles are attached at each end of the mold. A dried brick made in this mold would weigh approximately 36 pounds.