The flexibility of the paint film is the performance that the paint film will not break after being bent to a certain extent, so it is also called the bendability of the paint film. If the paint film is not damaged after the specified bending, it shows that the product has good flexibility.
To measure flexibility, the painted tinplate plate is bent on a shaft with a certain diameter, and it is expressed by the diameter of the smallest shaft that does not cause damage to the paint film after bending. There are six kinds of shaft diameters: 1, 2, 5, 10, 15, and 20 mm. The smaller the diameter of the bend, the greater the elongation of the outer surface of the paint film, so the flexibility is better through a 1mm diameter, worst at 20mm. Generally, the flexibility of the coating is required to be 1-3 mm.
When the paint film is bent on the shaft, the paint film will elongate. You can use a four-fold magnifying glass to observe whether there are any changes such as cracks, reticulation and peeling. If there is any abnormality, it is qualified. For the determination of putty flexibility, its thick layer is thicker, and its test principle is also a kind of bending test. The diameters of the bending rods are 100 and 50 mm respectively.
