Q. One of my crewmembers inadvertently scratched a composite post sleeve prior to installation, probably by sliding it across our chop saw stand when cutting it to length. We didn’t discover the scratch until after the entire rail system was installed, unfortunately. Is there a way to repair or repaint the sleeve (which is black) so that the scratch doesn’t show?
A. Mike Guertin, a custom home builder in East Greenwich, R.I., and a regular presenter at Deck Expo, responds: Because the smooth and shiny (or matte) surfaces of plastic and composite railings tend to highlight scuffs and scratches, I take extra care when working with the parts to avoid marring the finish. Inevitably, however, there always seem to be a number of dings that have to be addressed at the end of a large deck job. Often there are light scuffs on railing parts right out of the box that probably occurred during shipping. Chop saw stands are notorious for leaving scuffs and scratches. Dropping in rail sections often scuffs the post sleeves, especially when the rails have been cut for a snug fit. Darker colors seem to highlight the scuffs and dings, with black railings being the worst.
Fortunately, most of them can be removed with automotive rubbing or polishing compounds, a technique I learned painting cars as a kid. While these compounds aren’t used as much today with the clear-coat finishes that are typically found on cars, you can still find them at most automotive parts stores and paint shops. They’re also widely used to restore the finish on fiberglass boats, and are stocked by most marinas and hardware stores.
I use polishing (also sometimes called ‘buffing’) compound to take care of light scuffs and blemishes. If there are scratches or heavier scuffing, I use a rubbing compound first, which has a slightly more aggressive grit. While it's hard to eliminate a deep scratch using compound, I can usually blend it in so it's hardly visible. After working out scratches or heavy scuffing with rubbing compound, it may take a few rubs of polishing compound to match the sheen level of the railing. I usually can rub out the scuffs and scratches working the compounds by hand with a clean rag, though it is feasible to use a buffing head on a random orbital sander or angle grinder.