Cleaning tests of the different stones were made to determine the level of clean that could safely be achieved and not have the monument look "over-cleaned." Products tested were Triton X100, Orvus, Vulpex detergent, calcium hypochlorite, D/2 Industrial Grade Architectural Biocide, ProSoCo Light Duty Restoration Cleaner, and the Rotec Vortex Cleaning Process.
Biological Growths-D/2 Industrial Grade Architectural Biocide was used to clean the stone. It was applied to a prewetted surface with a garden-type sprayer and soft nylon bristle brushes were used. The solution was allowed to sit on the surface for approximately 5 to 15 minutes, then the cleaning reagents were thoroughly rinsed from the surface with large amounts of water. The rinsing was performed at 1,000 psi or less.
Carbon Crusts and General Staining were treated with the Rotec Vortex Cleaning Process which is a low-pressure micro-abrasive cleaning technology. The Vortex nozzle projects a low-pressure swirl of air, water, and an inert, micro-fine mineral powder to clean the surface. Regulating the air pressure, micro-abrasive flow rate, water volume and nozzle distance, allows the applicator to fine tune the cleaning action of the machine and compensate for different conditions of the stone.
The Rotec system was used to clean all areas of the granite above the granite plaques. Stubborn stains on the lower portion of the monument were cleaned by this method. The unit operated with a 3-fin turbine and various orifice size nozzles at 45 psi and at a working distance of 7 in. to 10 in. from the stone surface. In all applications a finely milled glass (Universal Ground Cullet M-1035) was used as the cleaning abrasive.
General Soiling - Application of ProSoCo Light Duty Restoration Cleaner was made to a prewetted surface using a soft nylon scrub brush. Cleaning started at the bottom of the monument and proceeded upward to help prevent streaking. The solution was rinsed with water pressure at less than 1000 psi.