Before using this on an outdoor concrete patio table, should a special primer be used?

You've come to the right place, Carol! We don't recommend applying Rust-Oleum Professional High Performance Enamel Spray directly to concrete because the porous nature of the surface will prevent the coating from adhering properly to the surface. Instead, we recommend priming the surface first with Rust-Oleum Zinsser Bulls Eye 1-2-3 Primer. To ensure adhesion, you'll need to check if there is a sealer on the surface first by performing a splash test. If the water beads up on the surface, that means there is a sealer that would need to be removed before applying any paint.

This does not need a primer.