Monument sign soft wash in Duluth, GA

In June 2026 we soft-washed a commercial monument sign in Duluth, GA. The sign had a stone base and painted metal panel face, and it had picked up a solid layer of algae and mildew across the stone courses, with rust staining running down from the metal hardware and moss beginning to set into the lower stone joints.

Monument signs sit low to the ground and close to irrigation zones, so the base stays damp longer than you'd expect. That combination of shade, moisture, and organic debris is exactly the environment where algae and moss establish quickly. The stone on this one had visible green-black coverage across most of the base, and the rust had tracked down far enough that it was bleeding onto the surrounding landscape border.

We used a soft-wash approach throughout. High pressure on painted metal panels risks lifting the finish or forcing water behind the face, and pressure on natural stone can work chemistry into the joints faster than a controlled dwell allows. A low-pressure sodium-hypochlorite mix with surfactant lets the chemistry do the work: we applied it to the stone base bottom-up, let it dwell to break down the algae and moss colonies, then rinsed top-down with a wide fan tip. The rust streaks got a separate oxalic-acid treatment before the main pass, which pulls iron oxide out of the stone pores without disturbing the surrounding surface. The metal panel face was rinsed separately at very low pressure once the base was clear.

The algae and mildew came off completely. The moss in the joints released cleanly, and the rust staining lightened to the point where it reads as a natural mineral variation rather than a maintenance issue. The stone base looks like it belongs with a freshly cleaned sign panel again.

Monument signs are often the last thing on a commercial property's cleaning list and the first thing a visitor sees. Duluth's humidity keeps the algae cycle moving; a soft wash every one to two years is usually enough to stay ahead of it before the moss starts working into the mortar joints.