Making clay bricks is an extensive process requiring the right clay and tools. Bricks can be sun dried or fired to high temperature using a kiln. The easiest to make are sun-dried adobe bricks. Whether you use naturally-occurring clay or buy clay from a distributor, it is always recommendable to test your clay recipe. Clay for bricks usually contains soil mixed with plastic clay and sand. You can form bricks manually using moulds, or with mechanical presses.
Research the type of clays available in your area. Contact local clay supply stores and brick manufacturers to select the right materials. Calculate the amount of clay you will need at around 2.27kg per brick. An average brick weighs about 2.27kg when it is dry. You will need about 1.5 gallons of water to make 10 bricks. Sand should not exceed 50% of the soil/clay portion and might be best at around 20 or 30 per cent. Start with a 50/50 ratio for soil and clay and test the results.
Make a mould to form your bricks using wooden planks and nails. Build a wooden box and leave the top (face) open for filling with clay. Make sure all edges are nailed tight to prevent the clay from leaking through. Use normal brick dimensions, which are 14-by-10-by-4 inches unless you want to make custom sized bricks. You can also make multiple moulds side-by-side in one unit. Manufacture handles for multiple moulds on each end to make them easier to handle when filled with clay.
Prepare your clay mixing station. Set up the table and the materials to be mixed beside the barrel or drum. Mix all ingredients thoroughly. Add water slowly until the mix has the consistency of dough. It should retain it's shape when formed but still be soft enough to use in moulds. Use a table to knead the clay as you would when making bread until you get an even consistency. Cover in plastic to prevent drying.
Lubricate the mould with water and sand before filling with clay. Pack the clay into the mould and trim excess along the top edge with a stick. Let it set in the mould for about a half hour, then carefully flip it upside down to remove the wet brick onto a board and store for drying. If the clay is too wet, let it set for about an hour
Dry the bricks by placing them on dry sand in the sun. Turn them as each side dries white in colour. Don't assume the brick is completely dry, even when it has turned white. Use a knife, sandpaper or a sponge with water to remove handling marks. Keep the bricks out of the rain. Dry the bricks for about three weeks to ensure that they are completely dry and ready to use.
To make these bricks much harder, inquire about firing them in a kiln.
Consult a construction expert before using sun-dried adobe bricks to build load bearing structures.