The Way to Paint Exterior Plastic Molding

The Way to Paint Exterior Plastic Molding

There are many aspects that influence a paint project and ultimately determine the final quality of this work. Like any other facet of decorative construction, each phase directly influences the next; the end result is that the product of the eye that you put into each step of the job. This is particularly true with regard to outside plastic moldings. The smoothness of this material combined with the inevitable adhesion of grime and residue in the elements makes a meticulous preparation job and the usage of the ideal primer paramount in attaining the long-term beauty that can highlight your home’s paint job for many years to come.

Prep Work

Gently wash down all outside moldings to be painted. Pay close attention to the edges — eliminating any present caulking with the putty knife, razor blade and paint scraper — and then wash the house wall or jambs from both sides of the molding at least a few inches.

Gently sand the entire molding surface with the sanding paper or sponge to raise the adhesion of your primer. Function in tight patterns so as to avoid leaving lines that can telegraph through the paint.

Wipe the entire surface of moldings with a fresh rag loaded with isopropyl alcohol to remove all sanding dust and residual oils, being careful to not touch the plastic with your fingers from this stage on. Allow the material to dry thoroughly.

Apply blue masking tape on either side of this moldings, as tight to the edges as possible, and run the corner of this putty knife gently along the edge of the tape to press it into the corner against the molding bit. If painting above other woodwork or sensitive plant life, be sure to shield from leaking or spillage by covering plants, putting old papers or taping construction paper against the wall at ground level.


Load the bottom edge of your 1-inch brush with the shellac primer and then apply to the edges of the molding with the bristles pointed inward harshly, so as to”cut-in” into the molding without having some unnecessary primer onto the tape. This will lower the probability of accidently peeling any fresh paint when the spraying is eliminated.

Load the bottom border of the 4-inch brush with primer and paint over the surface of this moldings in short, smooth strokes. Insert enough primer and invisibly in to your painted section to stop leave-off lines from forming. “Feather-in” in this way over the present edges repeatedly until you get one smooth coating of primer over the entire piece.

Allow primer to dry to manufacturer’s specifications, then gently”bulge”-sand any drip marks, leave-off brush or lines outlines that may be present. Wipe any sanding dust off with a fresh rag prior to painting.

Remove the blue masking tape, then caulk all seams between the moldings and the house or jambs. Adhere to the suggestion of the caulking gun with a moist rag pulled tightly over your fingertip to make a smooth and pliable bead, stopping when the extra starts to build up on the rag and become sloppy. Touch up the edges and continue around the perimeter.

Clean your brushes completely with denatured alcohol and a brush cleaning comb. Let them dry completely.

End Paint

Apply an oil-based or latex paint of your choice in the specific same manner as the primer coating, this time cutting-in very carefully against the caulking with the 1-inch brush.

Coat the remaining part of the molding face with the 4-inch brush, taking care at this stage to use just as much paint as is possible without producing a run or drip. This will ensure a thick, shiny coating.

Allow paint to dry completely to manufacturer’s specifications, then apply another coat, focusing only on smoothness and sharp, smooth cut-in lines.

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