Nail head rusting is the reddish-brown stains on the paint surface.

Possible cause

  • Non-galvanized iron nails have begun to rust, causing bleed-through to the top coat
  • Non-galvanized iron nails have not been countersunk and filled over
  • Galvanized nail heads have begun to rust after sanding or excessive weathering

 

Solution

When painting new exterior construction where non-galvanized nails have been used, it is advisable to first countersink the nail heads, then caulk them with a top quality, water-based all-acrylic caulk.

Each nail head area should be spot primed, then painted with a quality latex coating.

When repainting exteriors, where nail head rusting has occurred, wash off rust stains, sand the nail heads, then follow the same surface preparation procedures as for new construction.


More problem solving advice

Yellowing

Development of a yellow cast in aging paint solvent-based enamels

Wrinkling

A rough, crinkled paint surface occurring when paint forms a 'skin'.

Tannin staining

Brownish or tan discoloration on the paint surface due to migration of tannins from the substrate through the paint film.