How to Paint Interior Concrete Block Walls With a Faux River Stone Rock Finish

Apply a ¼-inch-thick layer of drywall compound to the block wall with a trowel, dragging the trowel across the wall to create the rough texture of river rock. Allow the compound to dry for 24 hours.

Add dark stone-colored interior paint to a paint tray. Roll a textured paint roller in the tray to soak up the paint. Apply a coat of paint to the wall with the textured paint roller. Allow the paint to dry 24 hours.

Add light and dark stone-colored glazes to two separate paint trays. Dab the different-sized sea sponges in the two glazes and apply them in a random pattern on the wall to simulate different-sized river stones.

Blot over the glazes made by the sea sponges with cheesecloth to soften the effect and create the smooth appearance of river stone. Add fine details to the stones like cracks or holes with a small round-tip art paintbrush.

Paint faux grout lines between the rocks with the small round-tip art paintbrush, using one or a combination of the glazes to create darker areas in the shadows of the rocks and highlighted areas between smaller rocks.