The Mogollon Railroad

[nachoman]

The sculptamold created the shape I wanted, but not the texture. Conglomerate is made of rock fragments, some as large as bowling balls or suitcases. After the sculptamold had set up for a few days, I coated it with a veneer to give the texture. First, I obtained a bottle of playground sand from my local playground. I took it home, poured it into a bucket of water with a little detergent, and washed the sand. After pouring the water from the bucket, I spread the sand out on a pan to dry.

Next, I took a generous scoop of joint compound and placed it in my plastic mixing bowl with a few spoonfulls of sand and a sprinkle of water. My goal was to create a sand-joint compound slurry that I could spread over the cliff face. Once the slurry was mixed up, I spread it over the sculptamold cliff using my pallette knives, doing my best to follow the pre-established shape I had previously created.

   

I specifically used joint compound here because it softens when re-wetted. Plaster or sculptamold set up permanently and won't work. Once the joint compound had mostly set up, I then took a cheap throw away paintbrush dunked in a tub of water, and gently brushed the rock face, in a direction parallel to the sedimentary beds (horizontal, in this case). The water and the paintbrush smoothed my sandy veneer, washing the joint compound from the sand and exposing the sand grains. I let the joint compound set up completely, and used a wetted paintbrush to smooth the surface again.

Once I had the texture the way I liked it, I applied an india ink wash, being careful not to overwork and re-soften the joint compound. Next, I applied a dilute wash of acrylic matte medium, thinned about 50/50 with water. The idea here was to seal and harden the surface so that additional paint washes would not soften the joint compound. Once the matte medium was dry, I applied washes of acrylic paint, until I got the color that I wanted.