Problem Solving Forum
July 7 - July 20, 2014
What is the best way to remove graffiti from the surface of historic stone masonry on a church while preserving the appearance properties of the substrate?
Jack Margraf of BioReTec on
August 21, 2014:
I have used either crushed glass or walnut shells ...read more I have used either crushed glass or walnut shells to abrasive blast at a low pressure followed by a waterborne chemical removal and wash. Sponge blasting also works well.