I recently spray painted my daughter’s TV stand. It is made of metal and particle board. The finished product looks good, but everything she puts on the shelves is sticking to the paint. Would a polyurethane help to prevent that?
Most paints will take up to a month to fully cure. This could be the main cause of the stickiness.
If you want extra protection you can apply a clear coat over paint. The exact type of clear depends on the type of paint. Use a varnish if the spray paint is an oil base or use an acrylic urethane if it is water based.