Clay brick making can be a rewarding experience, particularly if you plan to use your bricks to build a wall, or even a building. But for the novice who has never made bricks, it may take some detailed instructions, as well as information about materials, soils, and baking.
Soil Content Requirements
The soil you plan to use to make your bricks will need to be tested for content. You should not attempt to make bricks from soil that has a greater sand or silt content than content of clay. The suggested proportion should be 30% sand, 70% clay. But you can get by with a 50% proportion.
Testing Soil for Content
How can you test for sand, silt, and clay proportions in your soil? These components each have different weights. Each absorbs water at a different rate. You can use this information to test your soil. Soil filled halfway in a glass jar, mixed with water and filling the jar to 2/3 full, then allowed to settle for a couple days will produce three layers of soil at the jar's bottom. The bottom layer will be sand, the middle layer will be silt, the top layer will be clay.
Determining Content Percentages
You can determine the percent of sand, silt, or clay content in your soil by measuring the soil depth at bottom of your jar and making a note of this measurement. Then, measure the height of each level of sand, silt, and clay. By dividing the height of each soil type by the total soil height, you'll have the percent of each soil. For example, say, your total soil height is 2 inches, sand height is 1 inch, silt is .25 inch, and clay is .75 inch. This means, your soil is 50% sand, 12½% silt, and 37½% clay.
Preparing Your Mold
Your mold should be the standard size of a brick: 4x10x14 inches. You can make molds that produce multiple bricks or one that produces a single brick. The key requirement, though, will be to make your molds from wood. Nails are the best way to fasten the wall of your mold together. To avoid the wood pieces from splitting when nails are driven into them, use a drill and make a guide hole for each nail to be driven through.
Making the Brick
After your clay has been poured into the mold and has been allowed to sit for 30 minutes, you should be able to easily remove the whole brick from the mold.
Drying the Brick
For solar drying, the brick will need to be kept in direct sunshine until you see that the brick edges have turned white. Then, the brick should be turned on a different edge. After three weeks or more, the brick should be dried and ready for use. To fire dry a brick you'll need an oven (kiln) you can heat to as much as 1,800 degrees Fahrenheit. After solar drying your brick, you will need to place it in your hot oven (up to 1,800 degrees Fahrenheit) for an additional seven days. When it has finished drying, you will have your fired red brick.