EN 13523-24:2017

Overview

EN 13523-24:2017 is the CEN test method for assessing the resistance to blocking and pressure marking of organic coatings applied to metallic substrates (coil coated metals). The procedure reproduces the pressure and temperature conditions that can occur during coil storage and handling to evaluate surface damage, gloss transfer, plasticizer migration and sticking between coated faces.

Key elements of the method include:

• Use of a press to apply a uniform pressure at an elevated temperature
• Stacking of test panels with the two surfaces under test in contact
• Controlled exposure time, cooling and visual assessment using defined rating scales

Key Topics

• Scope and principle: The standard specifies how to prepare, stack and press test panels so that the effect of pressure and heat on an organic coating can be measured.

• Apparatus and samples: Ordinary laboratory equipment plus a press with adjustable pressure and temperature. Test panels should be flat, free of contamination and typically 120 mm × 100 mm. Sampling and panel preparation follow EN 13523-0.

• Recommended test parameters: Commonly used reference values in the standard are:

  • Pressure: 10 MPa ("eye to the sky") and 100 MPa ("eye to the side")
  • Temperature: 50 °C
  • Duration: 24 h
  • Cooling: allow the stack to cool to room temperature over 24 h while maintaining pressure

• Evaluation and ratings:

  • Blocking/sticking: Rated 0–4 (0 = no sticking; 4 = separation not possible).
  • Pressure marking: Rated 0–4 (0 = no mark; 4 = irreversible mark that cannot be removed after heating). Visual criteria reference EN ISO 13076 observation conditions.
  • In case of dispute, evaluation conditions are (23 ± 2) °C and relative humidity (50 ± 5) % in accordance with EN 23270.

• Plasticizer migration check: The test can indicate softening due to plasticizer transfer. Hardness change should be checked using EN 13523-4.

Applications

This test is used by manufacturers, coating formulators and quality control teams to:

• Verify coating resistance to blocking during coil storage and transport
• Compare formulations and backing coat combinations for durability
• Specify acceptance criteria for coated sheet and strip in procurement
• Identify plasticizer migration effects and surface gloss transfer issues

Related Standards

• EN 13523-0 - General introduction and sampling/panel requirements for coil coated metals
• EN 13523-4 - Pencil hardness (for assessing coating softening)
• EN 23270 - Conditioning temperatures and humidities for testing
• EN ISO 13076 - Lighting and procedures for visual assessment of coatings

For test reporting, include product identification, reference to EN 13523-24, coating system and parameters, pressure/temperature/duration, results (blocking and pressure marking ratings), and any deviations from the method.