To paint a decorative fiberglass column, clean the column with a damp cloth, and sand the column lightly with 120-grit sandpaper. Apply primer to the column using a paintbrush beginning at the top of the column and working downward. Allow the primer to dry, and apply one coat of exterior paint with a paintbrush. After the first coat of paint dries, apply an additional one to two coats of paint.
When painting fiberglass columns, use the same primer that is recommended for the type of paint, and avoid using spray paint. For instance, when painting the column with latex semi-gloss paint, use a primer that is designed for latex paint. Sand the column lightly when using flat paint, and more aggressively when using latex paint to ensure the paint adheres to the surface of the column.
To paint wooden columns, wash the columns with soapy water, and sand or scrape the columns to remove loose paint. Place a drop cloth under the column, and apply a high-quality primer to the column beginning at the bottom of the column. Allow the primer to dry, and paint the columns with one to two coats of exterior paint. When using oil-based primer, allow up to 24 hours for the primer to dry completely.