ISO 20567-1:2005 specifies three methods for the evaluation of the resistance of automobile finishes and other coatings to chilled-iron grit projected onto the surface under test to simulate the impact of small stones.
BS ISO 20567-1:2005 history
2005BS ISO 20567-1:2005 Paints and varnishes - Determination of stone-chip resistance of coatings - Multi-impact testing