• QAC-based biocide was applied to the upper and lower surfaces of the bullnose using a soft brush in a controlled manner , removing the chance for overspray to surrounding materials .
• The biocide was then allowed to dwell on the surface and penetrate the stone for 24 hours , ensuring maximum depth for neutralisation of spores .
• As was anticipated , used on its own , the biocide would not be sufficient to breakdown and remove the stabilised matter on the surface of the stonework or within the microstructure .
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