Modern Environment PPH-750 Pencil Hardness Tester is a scratch pencil Hardness Tester used to test the hardness of paint films. There is a level on the surface of the PPH-750 pencil Hardness Tester to ensure that the trolley is in a horizontal state, and it uses a blue metal shell, which has high hardness, good wear resistance, and is not easy to wear. The pencil lead pressure of the PPH-750 pencil Hardness Tester is 750G.
The PPH-750 pencil Hardness Tester is designed and manufactured with reference to the national standard GB/T6739-2006 "Determination of Paint Film Hardness by Pencil Method for Paints and Varnishes". It provides a fast and economical method to determine the scratch resistance (and other corresponding defects) performance.
Three points are used to contact the measured surface (two points are the rollers and one point is the pencil lead). The angle between the pencil and the measured surface is 45°. When the horizontal bubble is horizontal, the pressure exerted by the main body on the pencil lead is 750±10 grams. The hardness of a paint film is determined by passing a pencil with a known hardness scale across the paint film.

1. Prepare the substrate in accordance with the provisions of GB/T9271 "Standard Test Panels for Paints and Varnishes".
2. Sharpen the pencil until 5 to 6 mm of the lead is exposed (maintain the cylindrical shape of the lead). Keep the pencil perpendicular to the sandpaper to grind the end face of the lead until the end face becomes a complete circle with no broken or chipped edges. Pencils must be sharpened in this way before each use.
3. Unless otherwise agreed, the measurement shall be carried out under the conditions of 23±2℃ and 50±5% humidity.
4. Install the pencil according to the attached figure, push it at least 7 mm at a speed of 0.5~1 mm/second, and use the marked hardness of the hardest pencil that does not cause scratches of 3 mm or more on the paint film to indicate the pencil hardness of the paint film.
5. Measure twice in parallel. If the results of the second measurement are inconsistent (the difference exceeds 1 pencil hardness unit), the test should be repeated.
Each instrument is equipped with: 13 high-end drawing pencils (6H ~ 6B).
PPH-750 pencil Hardness Tester maintenance
1. The PPH-I 750 pencil Hardness Tester strives to rotate flexibly when used. After using it for a period of time, oil must be injected into the rotating parts such as the screw rod and bearings.
2. After using the PPH-I 750 pencil Hardness Tester for a period of time, the set screws and nuts must be tightened to avoid loosening.
Main technical differences before and after the revision of GB/T 6739 standard
| Difference content | Current standard GB/T 6739-1996 | Revised standard |
| Procurement status | Equivalent to JIS K 5400 -9 -8.4 | Equivalent to ISO 15184:1998 |
| Substrate available | Steel plate, tinplate version | Substrates that comply with the requirements of GB/T 9271 can be used, such as steel plates, tinplate plates, aluminum plates, wooden boards, etc. |
| applied load | Instrumental method: (1000 ±50)g | Instrumental method: (750 ±50)g |
| pencil hardness number | 9H, 8H, 7H, 6H, 5H, 4H, 3H, 2H, H, F, HB, B, 2B, 3B, 4B, 5B, 6B | 9H, 8H, 7H, 6H, 5H, 4H, 3H, 2H, H, F, HB, B, 2B, 3B, 4B, 5B, 6B, 7B, 8B, 9B |
| Exposed length of pencil lead | 3mm | 5~6mm |
| Tools for wiping the paint film surface after testing | Advanced drawing eraser | Soft cloth, cotton wool, or drawing eraser |