statement because no absolute reference material exists for impact resistance. 10. Comparison with Other Impact Standards | Standard | Key differences | Status | |----------|----------------|--------| | ASTM D2794 | Hemispherical tip 0.625 in, support die 0.64 in opening, weight 2 or 4 lb, manual drop tube. | Withdrawn 2019 | | ISO 6272-1 | Similar geometry (20 mm tip, 27 mm die opening) but requires calibrated drop height, allows pneumatic or automatic release. Includes precision data. | Active | | ASTM D5420 (Gardner impact) | For rigid plastics, not coatings on metal. Different tip/support sizes. | Active | | ASTM G14 | For pipeline coatings (larger indenter, heavier weight). | Active | | NCCA II-12 | Coil coating industry method, based on D2794 but with stricter panel specs. | Active |

This test is critical for industries where coated metal parts are exposed to mechanical abuse during manufacturing, assembly, transportation, or end-use (e.g., automotive body panels, appliances, coil-coated siding, drum coatings).

A weighted, hemispherical-tipped indenter (diameter: 0.625 in or 15.9 mm) is dropped from a specific height onto the coated side (or reverse side) of a test panel, causing rapid indentation. The coating is then evaluated for cracking or loss of adhesion.

is the closest direct replacement. However, results between D2794 and ISO 6272-1 are not directly interchangeable due to differences in indenter/die geometry and panel clamping. 11. Practical Applications & Typical Values | Coating type | Typical reverse impact (in·lb) | Notes | |--------------|-------------------------------|-------| | General industrial enamel | 20–40 | Often fails at lower end | | Automotive clearcoat | 40–80 | Requires very flexible chemistry | | Polyester coil coating | 80–160 | High flexibility for post-forming | | Epoxy powder coating | 80–120 | Thicker films (2–4 mils) | | High-build polyurethane | 100–160 | Impact modifiers added | | PVDF (Kynar) | 120–180 | Extremely flexible |