SIST EN ISO 12137:2011

Overview

EN ISO 12137:2011 - Paints and varnishes: Determination of mar resistance specifies a laboratory method to determine the mar resistance of a single coating or the top layer of a multi‑coat system using a curved (loop‑shaped or ring‑shaped) stylus. The standard is intended for comparative testing and provides relative ratings to distinguish coatings that show significant differences in resistance to surface blemishing (mar). It is the consolidated European adoption of ISO 12137:2011.

Key topics and technical requirements

• Scope & purpose
  • Measures mar resistance by pressing a curved stylus on a coated panel while moving the panel beneath it; identifies the minimum load that causes marring.
  • Best used for relative comparisons of coatings rather than absolute performance in all service conditions.
• Apparatus
  • Balanced‑beam mar‑resistance instrument with a stylus holder and sliding table; designed for loads up to 5 kg.
  • Load increments: typically 0.5 kg; 0.25 kg or 0.1 kg permitted for greater accuracy near the critical load.
• Stylus specifications
  • Loop‑shaped stylus: chromium‑plated steel rod, 1.6 mm diameter, U‑bend with outside radius (3.25 ± 0.05) mm.
  • Stylus hardness: Rockwell HRC56–HRC58; surface roughness