Coveside’s nest boxes are made of sustainably grown Eastern White Pine. They do not require paint or stain and should last 7+ years on average. The most important thing that can be done to preserve long term functionality is a good seasonal cleaning, inside and out, with a brush, soap and water and perhaps a weak bleach solution, followed by a thorough rinse, in order to remove germs and parasites.
Over time, the exterior wood will darken, turn gray and attain a weathered patina, much like barn board.
Should you wish to paint or stain, care must be taken not to use a petroleum-based product. Water-based (acrylic) only and on the exterior only.
Coveside’s preference in the way of wood preservatives are Tung Oil or Boiled Linseed Oil. Both are naturally derived, non-toxic and effective preservatives, if applied in a light seasonal coating.
Answered on 8/27/2013 by Steve from Homeclick