Sealing drywall seams after painting may not produce the same flawless result as sealing before painting. The newly applied compound may be slightly more noticeable due to the difference in texture compared to the surrounding painted surface. However, with careful application, sanding, priming, and painting, the difference can often be minimized to achieve an acceptable result.
While it is ideal to seal drywall seams before painting, it is possible to seal them after the paint job is complete. While this approach may require extra effort and attention to detail, it can help rectify overlooked seams or address new cracks that have appeared post-painting. By following the proper process of cleaning, applying compound, sanding, priming, and painting, you can achieve a satisfactory result and create a seamless finish on your drywall.