While it is technically possible to paint over rust without priming, it is generally not recommended. Without priming, the underlying rust will likely continue to spread beneath the paint layer, leading to future problems and a shorter lifespan for the paint job.
However, there are some instances where omitting primer might work. For example, if the rusted surface is thoroughly cleaned, sanded, and treated with a rust converter, which chemically reacts with the rust to stabilize it, painting without primer may be sufficient. Nonetheless, it is essential to closely monitor the area for any signs of rust emersion and be ready to address them promptly.
While it may be tempting to skip the priming step when painting over rust, it is generally not advisable. Priming provides crucial benefits such as corrosion prevention, improved adhesion, and enhanced durability. By investing the time and effort into proper surface preparation and priming, you can ensure a longer-lasting, smooth, and professional paint finish on your metal surfaces.