Application Failure Series – Painting Rusty Nail Heads

Rusty Nail Head Stains – Causes and Solutions

Industrial products are exposed to a variety of chemical, environmental, and temperature conditions. This increases the risk of corrosion, wrinkling, tearing, and other paint failures.  There are several types of paint failures with various reasons for each occurrence, making it difficult to identify the reason of their cause.  From selecting the wrong paint, failures related to adhesion, excessive chemical exposure, and design of painted structure, there are several minor and major factors that can ruin a well painted surface.  One of the common forms of paint failures that can transform any surface into ugly are stains from rusty nail heads.

When you consider industrial painting, it is common to find nails on the surface.  Nails serve an obvious purpose, but because of their chemical compound, they can rust if exposed to moisture.  That rust then stains the surface.  Unfortunately, repainting the surface is not the solution for hiding these spots, as the rust will reappear through the paint. Additionally, if a water based paint is applied, rusting can actually exasperate.  Galvanized nails have a coating of zinc on the surface which protects the nails from corrosion and rust. However, rusting can occur if the protective coating is broken by a hammer.

There are a few solutions for preventing or fixing rust stains:

  • If you are using non galvanized nails, you can spray them with a protective coat to prevent them from rusting. There are specific epoxy coating and paints available in market which can be used for the protective coat.
  • Rusting occurs due to presence of excessive moisture.  Check for leakages or any other sources of moisture on the surface.
  • Before you start repainting the surface, remove the rust layer and stained paint present around the nail. You can use a wire/stiff brush to remove rust or use sand paper.  While sanding, make sure you sand the head of the nail along with surrounding surface. You can also wash the satins with oxalic acid solution or a detergent.
  • Use a hammer to counter sink the nails, and apply a layer of coating on the top of the nail. Also, apply an undercoat on the area surrounding the nail. Once coating is dry, you can apply paint on the top.
  • For filling the gap created by counter sink nails, you can also use siliconized acrylic or all-acrylic caulk.

Whether the surface is old or new, rust stains are a common occurrence. These reddish brown stains need to be fixed properly or else they will reappear. So, always solve the problem from the core rather than fixing it over the surface.