a method of treating a surface to remove unwanted material therefrom , including providing a foamed glass article formed from a starting mixture including glass , a carbonate foaming agent , and a devitrification agent selected from the group potassium phosphate , potassium phosphate tribasic , sodium phosphate and combinations thereof , and contacting the surface with the foamed glass article while providing relative movement between the surface and the article . the crystal silica content of the foamed glass body is less than 1 weight percent . the surface is treated by sanding , rubbing , scraping , degreasing , polishing , cleaning , smoothing , depilling , grooming , stripping , degumming , and combinations thereof . the surface is selected from the group comprising wood , metal , plastic , fiberglass , porcelain , glass , enameled surfaces , ceramic , concrete , or tile , and belongs to a member of the group comprising pools , spas , griddles , grills , fryers , bottles , glassware , cement pieces , marble , granite , monuments , skin , animal hides , textiles , garments .