There are many techniques for replicating stone, from carving foam to using actual rocks from your backyard. You can also use Vallejo Industrial Thick Mud to model realistic stone texture.
I recently finished a scratchbuild of Han Solo in carbonite. The overall project turned out pretty well but lacked something. Based on feedback, I realized the exterior of the enclosure needed work. I decided it needed to look like the exterior of Jabba’s palace.
To create the stone texture, I turned to Vallejo Industrial Thick Mud (No. 26.809). This product has a gritty texture and gray color. I made a palette from a discarded plastic lid so I could close the jar of Thick Mud to keep it from drying out. Palette knives from an art supply store and paper towels are useful.
I masked the areas that needed to stay clean and applied the mud with a palette knife, working one surface at a time. I purposefully left the surface rough because of the project’s large scale; more smoothing would make sense for smaller scales.
After the mud dried, I wet-sanded the surface with a coarse sanding stick — about 100 grit. I frequently dipped the sanding stick in water to wash away the caking mud.
Next, I used an old paintbrush to wash and clean out the loose material from the textured surface.
After sanding and cleaning, the texture looks right for the scale. To replicate the look of individual stone blocks, I drew the separation lines with a straight edge and pencil directly onto the model.
Then, I drew a sharply pointed sculpting tool over the lines following a straight edge. This delineated each block and used the mud material’s coarseness to create realistic edges that are not too square.
This would have made a convincing wall of concrete block, and if that’s what you’re looking for, you can stop here. However, that wasn’t the color of the stone used for Jabba’s palace. So, I needed to do a little painting.
Craft paints work great for painting a surface like this. I went with gray, a rust color, and chocolate brown colors to get the effect I was looking for. For starters, I mixed a bit of all the colors for an earthy tone and dabbed the paint on to create shadow.
To deepen shadows and tone everything down, I applied a darker, brown-gray wash. Yes, it is dark, but do not worry. That will change with the next step.
After letting the wash dry, I used a large, soft brush to dry-brush a lighter, tan color. Go slow and let the color build until you get the contrast and tone you want.
When everything had dried, I mixed Tamiya Buff (No. XF-57) with Tamiya Thinner (No. X-20) in a 1:3 paint-to-thinner ratio and misted a light coat over the finish to lighten it a bit more. The finished result makes a big difference to the overall appearance of the piece.
Coming up with solutions when we don’t quite get what we want in the first place is one of the more enjoyable aspects of scale modeling. After using this technique to transform mud into stone, Han Solo looks even more entombed. The next time you need to replicate stone, give this simple technique a try.