Scratch resistance test of paints and varnishes

Scratches are cuts or scrapes that penetrate the surface of a coating, caused by contact with sharp objects. The scratch resistance test of paints and varnishes can use the constant load method and the load change method to determine the resistance of single coatings or composite coating systems of paints, varnishes or related products to needle scratches.
Zhongke Testing Reliability Experiment Center has the capability of reliability testing of various paints and varnishes, and provides professional scratch resistance test services for paints and varnishes.

Color paint is divided into primer and topcoat: primer is divided into primer, putty, mid-coat, sealer, anti-rust paint, etc.; topcoat is divided into enamel paint, special topcoat, etc.
The paint and film of varnish are transparent and are divided into ester varnish, shellac varnish, phenolic varnish, alkyd varnish, acrylic varnish, polyester varnish, high-performance varnish, fluorocarbon varnish, etc.

1. Load constant method
A scribe needle applied with a prescribed load is drawn across the coating at a constant speed. Examination of scratches determines whether, for a single specified test load, the coating has been scratched through to a specified extent (a "go/fail" test); or to determine the minimum test load required to penetrate the coating.
The specified test parameters are as follows:
1) The geometric shape of the scribing needle tip;
2) The range of test loads that can be used and the increment when increasing the load;
3) Method of lowering the height of the scribing needle to the coating surface;
4) Scratching needle running speed and minimum scratch length.
2. Load change method
The product or system to be tested is applied at a uniform thickness to a flat test panel with a uniform surface texture. After drying/curing, scratch resistance is determined by using an automated tester to push the test panel under a pointed scribe needle, which is mounted to press vertically downward onto the surface of the test panel.
Continuously increase the load on the test panel until the coating is scratched.

GB/T 9279.2-2015 Paints and varnishes - Determination of scratch resistance - Part 2: Load change method
ISO 1518-2: 2011 Paints and varnishes - Determination of scratch resistance - Part 2: Load change method
GB/T 9279.1-2015 Paints and varnishes - Determination of scratch resistance - Part 1: Constant load method
ISO 1518-1: 2011 Paints and varnishes - Determination of scratch resistance - Part 1: Constant load method