SIST EN ISO 20266:2021 PDF

Overview

EN ISO 20266:2020 (ISO 20266:2018) specifies an instrumental method for determining the image clarity - the degree of sharpness of a reflected or transmitted image - of paint films and coatings. The method measures how clearly an image is reproduced when reflected from or transmitted through a coated, flat surface. Image clarity is defined and reported as a percentage and is distinct from gloss or haze measurements.

Key topics and requirements

• Scope & limitation
  • Applies only to flat surfaces of coated test specimens.
  • Results are sensitive to temperature and humidity; conditioning requirements must be met or reported.
• Principle
  • A narrow light source (slit) produces a collimated beam; the image reflected or transmitted is focused through an optical mask and detected. Signal processing yields the image clarity value.
• Apparatus
  • Required components include a lamp, slit, collimating/de-collimating lenses, optical mask, light receptor and a black glass standard per ISO 17221.
• Specimen preparation & conditioning
  • Sample preparation follows ISO 1513 and ISO 1514 guidance.
  • Condition coated specimens at (23 ± 2) °C and (50 ± 5) % RH for at least 16 h, unless otherwise agreed.
  • Typical specimen size: 30 × 30 mm to 150 × 150 mm, thickness