The standard of adhesive force of paint is that the percentage of the amount of the glued finish or the electroplated layer and the grid. Paint adhesion can be classified into five grades.
The 0B grade has the worst paint film. If the paint has the 0B grade, the area of falling off paint will be greater than 65%.
The paint film of the 1B grade doesn't have good quality. The area of falling off paint of the 1B grade is smaller than that of the 0B grade, which is between 35% and 65%.
The 2B grade paint will fall from large or partial area along the cutting edge, and some of the grids will even fall completely. The area of falling off paint will be greater than 15% to 35%.
The 3B grade paint will fall along the cutting edge and crossing area. The area of falling off paint will be greater than 5% to 15%. Generally, the greater the number before the B, the smaller the area of falling off paint becomes.
The 4B grade paint has relatively good adhesive force, and small pieces of paint will fall only at the crossing part of the cutting line. The actual damage of the grid area is less or equal to 5%.
The 5B grade which is also the last grade has the highest degree of adhesive force. The cutting edge of the 5B grade paint is complete smooth, and the paint at the cutting edge of the grid doesn't fall at all.
Test Methods of Adhesive Force of Paint
There are many test methods of adhesive force of paint, but the most commonly used is the grid method. Scratch the grid with 15*15mm on the painting surface whose area is 50*100mm, and then tape the area of 15*15mm. Tightly press the tape by a tool. Hold one side of the tape and quickly tear the tape to check the falling paint. If the paint doesn't fall or the paint only falls in the coating area, the adhesive force of paint is qualified. If the paint falls between metal and coatings, the adhesive force of paint is unqualified.
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