🎨 Coating adhesion (cross-cut test)

Automotive PN-EN ISO 2409

Overview

STATUS (as of 02.11.2026). PN-EN ISO 2409:2021-03 — Polish version (published 01.07.2022), implements EN ISO 2409:2020 and ISO 2409:2020 [IDT], replaced PN-EN ISO 2409:2013-06 (Polish and English versions). The catalogue card carries no withdrawal notice. In the ISO catalogue the 2020 edition is at stage 90.92 (“to be revised”). The fifth ISO edition (31.08.2020) added Clauses 3 and 4, updated the requirements for single- and multi-blade cutting tools, deleted the references to commercially available cutters and — since final test specimens are assumed — the coating of test panels from Clause 7. Already the 2013 edition moved the procedures for removing loose paint to informative Annex A as examples and stopped specifying the adhesive strength of the tape, re-introduced the single-blade cutting tool, added a tool for motor-driven apparatus and a designation code for the test result.

SCOPE (Clause 1). The standard specifies a method for assessing the resistance of paint coatings and varnishes (including wood stains) to separation from substrates when a right-angle lattice pattern is cut into the coating, penetrating through to the substrate. The property determined by this empirical procedure depends among other things on the adhesion of the coating to the preceding coat or to the substrate, but the method is not a means of measuring adhesion — for measuring adhesion see ISO 4624. The test is primarily intended for the laboratory but is also suitable for field testing; it can be a pass/fail test or a six-step classification, and in a multi-coat system it allows the separation of individual coats to be assessed. It is carried out on finished objects or on specially prepared specimens, on hard (e.g. metal) and soft (e.g. wood, plaster) substrates — with different procedures. The method is not suitable for coatings with a total thickness of more than 250 µm or for textured coatings (for thicker ones — the X-cut method according to ISO 16276-2).

TOOLS (Clause 5). The cutting tool must produce a V-shaped cut through the total coating thickness, and the cutting edges must be in good condition. Single-blade tools (hand-held, for motor-driven apparatus, cutter with a rigid blade with a V-shaped edge) and multi-blade tools (six cutting edges spaced 1, 2 or 3 mm apart and two guide edges in one plane) are suitable for all coatings and substrates; every cut must reach the substrate, indenting it as little as possible. Motor-driven apparatus (more uniform cutting) is subject to agreement between the parties. The type of tool and the way of cutting influence the result — results obtained with different tools are not directly compared, and the same tool is used within a test series. Single-blade tools need guiding and spacing edges, and the assessment a hand lens with ×2 or ×3 magnification.

SPECIMEN AND PROCEDURE (Clauses 6–8). The substrate must be plain and free from deformation, with dimensions allowing the test at three positions at least 5 mm from each other and from the edge; minimum panel thickness — 10 mm for a soft substrate (e.g. wood), 0,25 mm for a hard one. The dry film thickness is determined according to ISO 2808 at or as near as possible to the test position. The test is carried out at (23 ± 2) °C and (50 ± 5) % relative humidity after conditioning the panels under these conditions for at least 16 h (in field tests the conditions are measured and recorded). Six cuts at equal spacing are made in each direction: up to 60 µm — 1 mm on hard substrates (e.g. metal, plastics) and 2 mm on soft ones (e.g. wood, plaster); 61 µm to 120 µm — 2 mm; 121 µm to 250 µm — 3 mm, for both types of substrate. Loose fragments of coating are removed (example procedures — including a brush and pressure-sensitive tape — are given in informative Annex A), and the cut area is examined and compared with the six-step classification.

CLASSIFICATION (according to the catalogue of an equipment distributor citing DIN EN ISO 2409). 0 — the edges of the cuts are completely smooth, none of the squares of the lattice is detached; 1 — detachment of small flakes of the coating at the intersections of the cuts, a cross-cut area not significantly greater than 5 % affected; 2 — the coating has flaked along the edges and/or at the intersections, an area significantly greater than 5 % but not significantly greater than 15 % affected; 3 — it has flaked along the edges partly or wholly in large ribbons and/or partly or wholly on different parts of the squares, significantly greater than 15 % but not significantly greater than 35 % affected; 4 — it has flaked along the edges in large ribbons and/or some squares have detached partly or wholly, significantly greater than 35 % but not significantly greater than 65 % affected; 5 — any degree of flaking that cannot be classified even by classification 4.

WHAT WE DO NOT GIVE HERE. The procedure of manual and motor-driven cutting (8.2–8.3), the number of determinations (8.1.5), the procedures for removing loose paint from Annex A (type of tape, time and angle of its removal), the designation code of the result (Clause 10) and precision (Clause 11) — the available text of the 2020 edition ends at 8.1.4, and we give the classification from a second source.

Method principle

Six parallel cuts and then six cuts perpendicular to them are made in the coating down to the substrate, at a spacing chosen according to the coating thickness and the type of substrate (1, 2 or 3 mm). Loose fragments of coating are removed, and the cut area is examined (lens ×2 or ×3) and compared with a six-step classification from 0 (smooth edges, nothing detached) to 5 (flaking greater than in class 4). The method does not measure adhesion and is not suitable for coatings thicker than 250 µm.

Applications

• Assessment of the resistance of paint and varnish coatings, including wood stains, to separation from the substrate — in the laboratory and in the field
• Pass/fail test or six-step classification
• Assessment of the separation of individual coats in a multi-coat system
• Tests on finished objects and specially prepared specimens, on hard (metal, plastics) and soft (wood, plaster) substrates
• Not for coatings with a total thickness above 250 µm (for them — X-cut according to ISO 16276-2) or textured coatings; adhesion measurement — ISO 4624

Key parameters

Standard

Standard number

PN-EN ISO 2409:2021-03

Title (PL)

Farby i lakiery — Badanie metodą siatki nacięć

Title (EN)

Paints and varnishes — Cross-cut test

Step-by-step procedure

1. Conditioning

   Condition the panels immediately before the test at (23 ± 2) °C and (50 ± 5) % relative humidity for at least 16 h and test under these conditions (in the field, measure and record the conditions).

2. Coating thickness

   Determine the dry film thickness according to ISO 2808 at or as near as possible to the test position and choose the spacing of cuts according to the thickness and the type of substrate.

3. Cuts

   Make six parallel cuts to the substrate and then six perpendicular ones, with the same tool throughout the series; every cut must reach the substrate as shallowly as possible.

4. Removal of loose coating

   Remove loose fragments of coating by one of the procedures in informative Annex A.

5. Evaluation

   Examine the cut area (lens ×2 or ×3) and assign a class 0–5 according to the six-step classification or assess pass/fail.

6. Repetition and report

   Carry out the test at three positions at least 5 mm from each other and from the edge; designate the result and report it according to Clauses 10 and 12.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• The available text of the standard contains no safety requirements — the rules for working with cutting tools are set by the laboratory on the basis of a risk assessment

Frequently asked questions