Although most any kind of paint can be used to finish a windowsill, certain types of paint are more appropriate, depending on the homeowner's taste. The condition of the windowsill may require particular preparation techniques or the paint will ultimately peel.
Satin latex paint is appropriate for covering walls. Some homeowners choose this type of paint for their windowsills because it is less glossy than other types of paint. A satin latex coating is suitable for those who would like their windowsills to blend in with the surrounding walls.
Gloss latex paint is the most common choice for windowsills. It provides a high sheen and an extra element of durability. Gloss latex paint is resistant to scrapes and scratches and much easier to clean than satin finishes. It also is suitable for homeowners who want their trim to stand out.
Semi-gloss latex paint is a good compromise for homeowners looking for an attractive sheen that's not overpowering. Though not as durable as full-gloss paints, semigloss is almost as easy to clean. It is also more durable than satin latex.
Oil-based paints are glossy and far more durable than latex paints. However, many homeowners balk at oil-based coatings because they tend to emit unpleasant fumes.
Applicators should never paint over bare wood windowsills. The finish will eventually shed. Bare wood requires a latex primer prior to painting. Stained windowsills require an oil-based primer. Most oil-based primers are not compatible with latex paints. Kilz brand oil-based primer can be used with latex coatings. Do-it-yourselfers should inspect the label to ensure that the oil-based primer they choose is formulated to work with latex paints.