Should vinyl be painted?

No.  Vinyl fence and vinyl rail systems should never be painted.

Why?  It voids our lineal supplier's warranty, for one. 

Our supplier warns:

            “This Warranty does not cover situations and events beyond normal exposure conditions, including, without limitation…

Exposure to airborne pollutants, harmful chemicals, mineral-rich water, or paint, varnish or other coating being applied to the fence or railing” (emphasis added)

Second, vinyl needs to expand and contract. Painting inhibits this inherent quality and, if painted, may cause the vinyl to buckle and distort, as the vinyl finds a way to move slightly in the heat of the day and the cool of the night. You may have seen this type of movement with other vinyl products, like vinyl siding. Vinyl siding is hung, not firmly face-nailed in place, to allow for this expansion and contraction feature. Even though vinyl fence and vinyl rail profiles are much thicker than vinyl siding, meaning the movement is much less, the product still needs to be allowed to expand and contract. Painting locks in these small, imperceptable movements and may lead to big problems.

Google "Can vinyl fence be painted" and you will find paint suppliers who say, "Yes, it can."  Be careful to find out what their warranty is, since painting voids your vinyl product's warranty. These articles may include several warnings, like
 
"Vinyl fencing is specifically designed to be nearly maintenance free and painting is not recommended. If you decide to paint, your fence will require more attention, including a fresh painting every few years if the paint cracks, peels or fades.
  • Painting the fence may void your warranty.
  • Wear safety goggles or glasses if you use a paint sprayer.
  • Painting a vinyl fence can damage the surface of the vinyl"

           source: EHOW
Granted, vinyl extrusion manufacturers produce profiles in color.  Southern regularly offers an Almond alterrnative, plus special order colors, too.  However, the chemistry is carefully mixed within and throughout the PVC materials with stabilizers and other special additives to allow these colors to perform for years to come. Don't add a paint coating, even if water-based, that voids the warranty and turns your beautiful vinyl fence into a sunflower, following the sun throughout the day, warping and buckling and creating headaches you never bargained for when you bought your beautiful, low-maintenance vinyl fence or rail.

Southern Vinyl sells our vinyl systems as low maintenance.  Painting is the opposite of low maintenance.
Don't end up with this . . . But enjoy your free time, with this . . .