Clean your plastic laminate surfaces with trisodium phosphate (TSP) and a rag. Even if your bathroom already appears clean, oily residue may be hiding on the laminate surface. TSP cuts through oils and other stuck-on bathroom grime easily.
Dry the recently-cleaned laminate surfaces with a towel.
Stick painter's tape on nearby trim or bathroom fixtures. Painter's tape helps protect surfaces from accidental brush strokes.
Lay plastic sheets on the bathroom floor or on items that are too big for painter's tape to cover.
Prime the plastic laminate with high-adhesion alkyd primer. High-adhesion primers are designed to adhere to slick laminated surfaces and alkyd varieties hold up better when exposed to bathroom moisture. These specialty primers are available at most hardware supply stores. Apply the primer to edges with a synthetic-bristle paintbrush and use a medium-nap roller for larger plastic laminate surfaces. Wait 24 hours for the primer to fully cure.
Paint the plastic laminate bathroom surfaces with high-gloss oil-base paint. High-gloss paints are easy to clean, making them the best choice for bathroom surfaces. Oil-base paints are also better suited for moist bathroom environments when compared to latex paint. Use a foam brush for edges and a foam roller on main surfaces.
Apply a second coat after two hours. A well-primed laminate surface is usually fully covered in just two coats.
Remove the painter's tape and protective sheets after 24 full hours. The paint will be dry in just one or two but it won't fully cure for a full 24 hours.