You can paint black wrought iron fence with most any type of paint; however, some types will prove to be more sustainable in the long term. More important than the type of color you choose is the type of primer. Learn how to prepare the fence, or it will reject any type of color.
No type of paint will bind to wrought iron only. Before you even think about applying a topcoat, prime the fence with the right type of basecoat. Latex and acrylic primers will not bind to black wrought iron fence because it is smart and non-porous. For a durable base, apply an acid-based metal etching primer. This first coating etches the fence and allows it to be better suited for its painted surface.
Acrylic latex paint
Acrylic latex paint is well suited for exterior surfaces as it has the ability to expand and contract when the temperature is high and low. Regular latex paint does not do this well and should not be used on outdoor wrought iron fences. Enamel is also well suited for external conditions; it is much more durable than water-based acrylic latex paint. If you want a stylish finish that can withstand relatively high levels of physical coercion, paint your wrought iron fence with enamel.
Painting wrought iron with a brush can be a laborious quest. For faster, more efficient results, apply the primer base and painted surface, using a mini-roller. Be careful that the etching primer you choose is formulated to prevent rust, or new finishes become a reddish orange when exposed to moisture.