What happens if you don't put paint over primer?

What happens if you don't put paint over primer? If you don't put paint over primer, primer will be exposed and may have several issues, as primer is not designed as durable finish. Primer is porous, flat, and not washable, so it will attract dirt, scuff easily, and be hard to clean, showing marks and stains. It may also look uneven, chalky, and not color-accurate, lacking sheen and depth of finish paint. Exterior primer left unpainted will degrade faster from UV, rain, and weather, as it is not weather-resistant without topcoat, leading to peeling and failure. Interior primer left exposed may absorb moisture and odors. Some primers like Zinsser 1-2-3 can be left temporarily in low-traffic areas like closets if white is acceptable, but for walls and high-traffic areas, topcoat is needed for protection, washability, and appearance. Manufacturer recommendations say to topcoat within 30 days for best adhesion, as primer left too long may collect dust and reduce adhesion. So if you don't paint over primer, you get poor appearance, low durability, and need to repaint sooner, especially outdoors.