Grit and shot surface comparators are used to test the roughness of the surface.
The roughness is estimated and compared to the different areas on the surface comparator by visual examination.
If necessary, by scraping with a finger nail (but never with the skin as this will contaminate the blast).
Both grit and shot blasted surfaces can be compared using either comparator.
No. 017 for Shot blasting
No. 018 Grit-blasting
These two comparators are specially designed to check the roughness of steel surfaces which have been blast cleaned to cleanliness grades SA 2.5 and SA 3 in preparation for painting. They conform to ISO 8503.
