The treatment of hard surfaces by impacts of fine hard granules continually bombarded against them, as for peening, brightening, texturizing, compacting, reforming and/or cleaning adhesions from plates and other articles of steel, aluminum, or hard plastics, is accomplished with extraordinary effectiveness, yet with minimal loss of the blasting material due to breakdown, by providing and utilizing for the treatments selectively sized fractions having grain sizes limited to the ranges of - 100/+200 mesh, -100/+140 mesh, -140/+200 mesh and -200/+325 mesh grain sizes, of the rounded oblong grains, having a specific gravity of about 4. 7, of a mass of refined zircon sand.
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