Composite decking is often touted as a maintenance free alternative to lumber, yet over time its original color will fade, and some individual boards can become stained by spills..Yes you can Stain Composite Decking, but only for certain types of composite decking. Several years ago we wereed out to a Raleigh home that had an expansive multi level trex composite deck. The deck had the black mold spots everywhere, which seems to be a very common problem with the older trex composite decks..Yes, you can paint or stain Trex decking or railing to achieve a custom color, but it is . decking that has been faded can be painted or stained at any time, even..Although Trex products never need to be painted or stained for protection, Trex can be painted either to refresh the designated color or to achieve a custom color. Trex products can be painted or stained at any time, even years after they have been installed..