Louver doors are specially designed with horizontal wooden vents that help encourage air flow between rooms. If you plan to paint these types of doors, you'll have to be especially cautious to avoid two potential mistakes. First, you must use care when applying the paint as painting these vents often causes drips and splatters. Also, if you over-apply the paint, you risk sealing the air space between the vents, eliminating the door's ability to effectively perform its function.
Slip masking paper--an inexpensive type of brown craft paper that has temporary water resistant properties--underneath each door, effectively protecting the flooring from drips and splatters. Secure the edges of the paper with blue painter's tape--this will prevent the paper from rolling up and sticking to the wet paint.
Protect any areas you do not want painted by covering them with blue painter's tape. Remove the doorknobs using a screwdriver.
Apply latex primer to the door using the 3-inch latex paintbrush. Paint the horizontal vents first. Brush horizontally. Apply only a thin coat so as not to seal the vents shut. Continue painting the remainder of the door after you've painted all of the vents.
Brush over the vents horizontally using a dry 2-inch latex paintbrush, effectively removing any excess primer and smoothing any runs or dips. Work quickly before the primer begins to dry. Do not dip the brush in any primer during the smoothing process. Allow the primer to dry for two hours.
Clean both brushes using water.
Apply paint to the louver doors in the exact same manner as you did the primer. Allow the paint to dry for two hours, then apply an additional coat, if necessary. Allow the second coat to dry thoroughly.
Reattach the doorknobs.