Pencil hardness testing of film

Coating film pencil hardness is a commonly used method for testing the physical properties of coating films, which is used to evaluate the hardness and wear resistance of coating films. During the test, use pencils with different hardness to scratch the surface of the coating, and determine the hardness level of the coating according to the hardness of the pencil.

The coating pencil hardness test generally uses pencils with a pencil hardness grade of 6B~8H, of which 6B is the softest pencil and 8H is the hardest pencil. When testing, first use a standardized scratch Tester to scratch the pencil along a certain length at an angle of 45 degrees on the coating to be tested, and then judge according to whether the pencil can leave obvious scratches on the coating The hardness level of the coating. If the coating cannot be scratched visibly by the pencil, then the pencil hardness grade is gradually increased until the pencil can leave visibly scratched on the coating.

The pencil hardness test of the coating film is usually applicable to the case of relatively low hardness of the coating, such as wood coatings, wall coatings, etc. The test method is simple and easy, and does not require expensive test equipment, so it is widely used in industrial production and quality control of coating products.

Pencil Hardness Testers are generally divided into two types: American ASTM D3363 and European ISO 15184.

The following is the test procedure of ASTM D3363:

1. Prepare the surface to be tested by keeping it dry, clean, smooth and flat.

2. Have a pencil Hardness Tester and various pencils ready.

3. Choose a suitable pencil, sharpen it first, and mark it on one side.

4. Place the pencil Hardness Tester perpendicular to the surface to be tested, and gently press down on the pencil so that it makes contact with the surface.

5. Scrape the marked side of the pencil back and forth across the surface to be tested until no more visible marks are produced.

6. Check for pencil scratches with a microscope or with the naked eye. According to the depth of the impression left by the pencil on the surface to be tested, judge the hardness level of the pencil.

The test procedure of ISO 15184 is similar to ASTM D3363, except that the pencil specifications and hardness grades used are different, and different scoring standards are used to evaluate the hardness grade of the coating.