What grades are there for the quality evaluation of paint film resistance to heat and humidity and salt spray?
After the paint film has been tested for resistance to heat and humidity and salt spray, according to the degree of corrosion of the paint film, the corrosion grade in the following table is evaluated:
| Corrosion resistance grade | Corrosiveness |
| Grade 1 (good) | Corrosion-resistant level Corrosion degree 1. Slight loss of light (5%~30%) 2. Slight discoloration 3. There is no significant change on the surface of the paint film, and less than 5% of bubbles are allowed 4. No rust allowed 5. Lightly pulverized 6. Slight cracks ① Invisible to the naked eye, but clearly visible under a four-fold magnifying glass ② Obvious cracks are less than 1o% ⑧Several sparse hairlike cracks 7. Small pieces fall off, the diameter is less than 0.5mm 1. Obvious loss of light (21%~50%) 2. Obvious discoloration 3. The area of microbubbles on the surface of the paint film is less than 50%, and the area of local small bubbles is 4% less than 1% of the medium bubble area Level 2 (qualified) 4. The diameter of the rust point is less than 0.5 mm. 5. Significant chalking 6. Moderate cracks A. Shallow and obvious cracks reaching ll%~loo% B. Those with deep cracks below 1o% 7. Small flakes fall off up to 2%, and the diameter of the small flakes is 0.6~1mm |
| Level 2 (Qualified) | 1. Obvious loss of light (21%~50%) 2. Obvious discoloration 3. The area of microbubbles on the surface of the paint film is less than 50%, the area of local small bubbles is less than 4%, and the area of medium bubbles is less than 1%. 4. The diameter of the rust point is less than 0.5 mm. 5. Significant chalking 6. Moderate cracks A. Shallow and obvious cracks reaching ll%~loo% B. Those with deep cracks below 1o% 7. Small flakes fall off up to 2%, and the diameter of the small flakes is 0.6~1mm |