Overview
ISO 18951-1:2022 - Imaging materials - Scratch resistance of photographic prints - Part 1: General test method - defines a standardized approach to assess the scratch resistance of photographic prints. The document sets out the test target, general test method, sample preparation, conditioning, evaluation and reporting requirements for prints produced by a wide range of technologies (silver halide, electrophotography, inkjet, dye‑sublimation, dye transfer) and on diverse substrates (paper, plastic, glass, metal). It applies to both unprotected prints and those with coatings or laminations. The standard provides guidance for reproducible testing but does not prescribe acceptance limits - those are left to users and intended applications.
Key topics and technical requirements
- Test principle: A stylus is moved across the print under controlled load and speed to introduce localized stresses (indentation, friction) and produce damage. Results are characterized by a critical load (minimum load producing a defined damage level).
- Stylus classification: Defines scratch scales by stylus size - nano (<10 µm), micro (≥10 µm and <0.5 mm), macro (≥0.5 mm) - with examples (2 µm, 50 µm, 4 mm).
- Test methods: Outlines constant‑load and variable‑load procedures and recommends selection of stylus geometry, load and linear velocity appropriate to the expected use.
- Sample handling: Requirements for sample preparation and conditioning to ensure reproducibility.
- Damage assessment: Defines damage levels (level 0 to level 3) and evaluation routes - visual inspection and instrumented measurement-based evaluation (critical loads F_c1, F_c2, F_c3).
- Reporting: Specifies what information to record (equipment, stylus geometry, loads, velocity, substrate/coating details, results) to enable comparison and traceability.
- Limitations: Emphasizes that results depend strongly on equipment and stylus geometry and should not be directly compared across different test setups.
Applications and users
ISO 18951-1:2022 is practical for:
- Printer manufacturers and ink formulators evaluating surface durability of print/ink/substrate combinations.
- Photo labs and print houses performing QC and comparing supplier performance.
- Material scientists and converters assessing coatings, laminates and substrate resistance to handling.
- Contracting parties using the method to agree test protocols (e.g., supplier/customer QC specifications).
Typical uses include product development (selecting ink/substrate/coating combinations), quality control, and comparative durability testing.
Related standards
Keywords: ISO 18951-1:2022, scratch resistance, photographic prints, test method, critical load, stylus, sclerometer, imaging materials, print durability.