How to evaluate the appearance of the paint film of anti-corrosion coatings by the naked eye?

The appearance quality of the paint film is mainly evaluated by the naked eye. Although industrial anti-corrosion coatings are different from highly decorative paint films such as automotive paints, they also have certain decorative requirements. Nowadays, many steel structures, such as airports and bridges, require the use of high-gloss topcoats, such as acrylic polyurethane topcoats, acrylic polysiloxane paints, etc. Therefore, it is very important to conduct an on-site test of the gloss of the paint. In addition, when painting and repairing steel structures, it is necessary to test the gloss retention of the coating.