1 Definition, Purpose and Significance
Refers to the degree of difficulty of producing a smooth matte surface after the paint film or putty layer is polished (dry or wet) with pumice, sandpaper and other materials .
Sanding property is a practical performance of paint film, especially for primer and putty, it is an important performance index.
In the process of sample preparation or in the process of physical painting, it is often encountered that the surface of the paint film must be polished to remove particles and debris on the surface of the paint film to form a smooth and matte surface to improve the surface of the upper paint film. Flatness, to achieve satisfactory construction quality, but improve the adhesion between the paint film layers, can more effectively prevent the penetration of water vapor and other corrosive media, greatly improving the protection of the paint film.
2 Relevant standards
GB/T 1770_79(89) Determination of abrasiveness of primer and putty film
3 Introduction to key points of inspection methods
3.1 Measuring principle
The surface of the paint film is polished by instruments or by hand, and the sandability of the paint film is evaluated by observing the surface phenomenon of the paint film.
3.2 Instruments and equipment
Grindability Tester, as shown in Figure 10.
3.3 Operation points
On the grinding head of the instrument, install the water-sand group 1 of the specified model, add a certain load, and the sample to be ground. The plate: place it on the magnetic workbench: After the grinding head is polished by a certain number of reciprocating times, observe the surface of the sample Phenomenon.
When grinding by hand, use water sandpaper to rub evenly on the sample plate, either dry or wet. (Related instruments: Grinder)
3.4 Result Judgment
The results are evaluated with two samples of similar phenomena. Judging whether the surface is uniform, smooth and matte, whether there are micro-groups that cannot be worn away and become soft after heat.
3.5 Precautions
3.5,1 Pay attention to the uniformity of force and grinding speed when grinding by hand.
3.5.2 Attention should be paid to selecting the specified type of water sandpaper during the measurement.
