Taking our cue from Joe Tibbetts at Adobe Building School, we knew we wanted “stabilized adobe” that does not melt in the rain thus avoiding the necessity of having to plaster the exterior of the building. Stabilized adobe is accomplished by adding a specific amount of asphalt emulsion, which coats the clay particles and prevents them from melting. Too little asphalt emulsion will leave the adobe subject to melting in the rain, and too much will make the adobe brick weak.
I made small test bricks, keeping track of the weight of the dirt and the weight of the asphalt emulsion in each small test brick. Following Joe’s instructions I placed each test brick on a sponge sitting in a pan of water overnight, weighing each brick before and after. The brick could not absorb more than 3% of its weight overnight to qualify as “stabilized”. From this test we extrapolated our formula for mixing large amounts of adobe mud: 40 shovels of dirt to 7 gallons of water to 2.5 gallons of asphalt emulsion.
The grading company had left us a pile of dirt for making the adobe bricks, but it had to be screened to eliminate any rocks over a half inch. Bruce had come across a huge abandoned screen in his treks across the desert, hauled it to the building site, and with his bobcat screened batches of dirt as needed to make the adobe mud.
Bruce made a couple of forms using 1 x 4 lumber and lined them with sheet metal so the mud would not stick to the inside. Each form made two bricks 16 x 7.5 x 4. We used a mortar mixer to mix the mud. On the level house pad, we laid down black paper, set the form down, filled it with thick mud, so thick that you could lift the form immediately and the brick would hold its shape. By the end of the hot summer day, you could roll the bricks up on edge to finish drying for a week, after which the bricks could be stacked, on an angle to prevent breakage.
Our first weekend making bricks was the 4th of July. We had set up a permanent campground because we were living an hour and a half away. That weekend my niece, Hilarie, and three of her girlfriends, all members of the Cal Berkeley crew team came to help us make bricks. I’m talking very strong girls who could maneuver a wheelbarrow full of mud and place it wherever needed. They stayed for three days and we felt pretty good about how the adobes were turning out.
The following weekend, it was just Bruce and myself and we quickly came to the realization that we needed help! Bruce went down to the corner in Littlerock where guys were looking for work and we ended up with a great team, the same four guys every weekend, and if one couldn’t come, his cousin would come in his place. They ended up being a talented self-organizing team who would get started even before we showed up on Saturday mornings. Working every weekend that summer we made 14,500 adobe bricks, the amount recommended by our architect, Rob Mehl.