How to brush antirust paint?

Traditional method (1): derusting first to get the true color of iron, and then coloring. Traditional method (2): firstly, remove rust to get the true color of iron, then brush phosphating solution, wash with water to dry, and then spray paint for a long time.

The most advanced technology: using anti-rust primer, rust can be directly transformed, and the anti-rust life is more than 3-5 years. Brush twice for a long time, the color will be black.