Nail Head Rusting - Causes & Solutions

Nothing can ruin a nice, painted surface more than the appearance of reddish-brown stains. There stains are caused by nail heads rusting through the paint. Understanding the causes and solutions of this problem can help you prevent and eliminate these unsightly blemishes on your structure.
 

Use of non-galvanized nails

Galvanized nails are protected from the elements. Through a galvanization process these nails are coated with a zinc coating. The zinc coating creates a protective barrier that shields the nails from damage. The coating dissolves before the inside metal experiences any damage. A non-galvanized nail is not protected, leaving it vulnerable if it comes into contact with moisture.
 

Non-galvanized iron nails were not countersunk and filled

While is not necessary to use galvanized nails, you need to take the proper care to make the nails rust-proof. Countersinking and filling non-galvanized nails is crucial. A nail punch can place the nails 1/8 inch below the wood surface. To protect the nail, apply a layer of undercoat. Once this is done, a high quality compound caulk is used to fill the nail. This action acts the same as a protective coat of a galvanized nail.
 

Galvanized nails were sanded or exposed to excessive weathering

Galvanized nails withstand decades of wear; however, the powdered coating of a galvanized nail is not impenetrable. Routine maintenance that involves sanding or extreme weather can prematurely remove the nail's coating. If the nail comes in contact with moisture, it can rust.
 

Solutions

There are a few solutions to prevent and fix the appearance of rusting nails. If you use nails that are not galvanized, you can spray them with a product that prevents rust. Applying petroleum jelly to nails also works as a very temporary solution. Replacing the nails is another option. The most common solution is to countersink and fill the nail.

Those ugly reddish-brown spots that appear on paint are caused by nails heads rusting. As bad as it looks, there are several solutions to remedy and prevent this from re-occurring, so your surfaces stay beautifully painted.

Primers and Finishes

Priming and proper surface preparation are essential with a corrosion resistant primer. 
Select a top quality exterior paint in the color and sheen of your choice. 

Substrates, Primers

Substrate: Ferrous Metal 
Primer: 1711 Kel-Guard Rust Inhib. Primer 
Finish Coats: 1240 Acry-Shield Exterior Flat Finish 
1245 Acry-Velvet Ext. Low Sheen Finish 
1250 Acry-Lustre Ext. Semi-Gloss Finish 
1235 Seasons Ext. 100% Acrylic Flat 
1236 Seasons Ext. 100% Acrylic Low Sheen