Pro tip

Any surface not being painted (e.g. coping and control joints) should be protected. One should consult the deck paint application instructions to determine if it is viable to paint the control joints. There are also specific products on the market designed to be used when painting pool coping. Pool professionals should choose the best paint based on the surface onto which it will be applied.
Prime the concrete surface
When the deck surface is completely clean and free of loose paint, dirt, oils, or solutions, applying an adhesion primer is recommended to ensure a successful deck painting renovation.
When using a deck paint primer, one should be sure to stir thoroughly before use. Professionals can apply these primers using a roller or spray gun paying careful attention to ensure an even, properly sized coat. Applying more than one coat or excessively heavy films will lead to insufficient through-drying of the paint and will yield soft paint films.
Additionally, deck primers should not be applied on extremely humid days (90 per cent relative humidity [RH] or more) or when rain is expected. Applying these primers in the late afternoon—when working outdoors—also is not recommended as the wet film may be adversely affected by dew. When working in cooler climates be sure the air and surface temperatures will remain at or above 4 C (40 F) for at least eight hours after application.

The concrete should be completely clean and dry before beginning to use the primer. All imperfections, cracks, etc. should also be patched using concrete filler and flexible joint fillers. Silicone repair products should not be used as primers and paints will not adhere to the silicone.
It is recommended professionals use a 9.5 mm (0.375 in.) or 13 mm (0.5 in.) roller because these primers are mostly two-component, water-based epoxy primers. Properly sized rollers promote good adhesion between concrete or previously painted surfaces and a deck paint topcoat. One coat of adhesion primer is sufficient before the specialty deck paint is applied.
Any pool deck surface can be painted, whether concrete, wood, composite, or other. Even previously painted decks can be repainted. In fact, with most deck paints, it is not necessary to know what type of paint was previously used on the deck as they can be applied by abrading the surface and covering with a coat of adhesion primer. Two coats of specialty deck paint should be used when covering a previously painted surface.