Commercial Paint Problems & Solutions – Painting Galvanized Steel

Galvanized steel has exceptional benefits for any plant or facility.  It is durable and can tolerate high moisture, due to the zinc it’s boiled in.  However, although versatile, it is a challenge to coat due to the oil residue that protects the substrate.

Here’s how Commercial Painters Avoid Paint Peeling From Galvanized Surfaces

Galvanized steel is frequently used in many commercial and residential settings.  It’s used for gutters, down spouts, corrugated decking, and many other common applications.  Although it is tolerant to weather, due to its zinc coating, it is very challenging to paint.

Galvanized metal will require a strong detergent cleaning.  And there’s no way to get around this.  The oil based residue is applied to help protect the galvanized metal.  So hot water detergent cleaning will be necessary to ensure that the oil residue is adequately removed.

Now you may be asking, isn’t that oil film on the galvanized metal somehow protecting the metal?  And I would reply, yes, you are correct.  But the paint will replace the necessity for the oil residue, as long as you take the necessary steps to coat it.

The first step would be to apply a rust-inhibitive primer.  A rust inhibitive primer will adhere tightly to the substrate, so that water cannot penetrate, and access the surface.  And after the primer has been applied, the applicator will want to apply a proper coat of paint.

A proper coat of paint is determined by where the location of the galvanized metal.  Now, if it’s outdoors, you’ll want to limit your products to latex paints, or urethane paints.  Both have excellent UV resistance, and can be applied outdoors with optimal success, as indicated in our previous article on chalking.

Treating Galvanized Substrates

Now, detergent washing is the easiest method of preparing the surface of galvanized steel.  However, it’s also a good idea to apply some metal conditioner to the substrate.  Here are some viable options:

  • Galvaprep – Galvaprep is a phosphoric acid-based coating that is designed to produce a zinc phosphate conversion.  This conversion increases the adhesion quality for paint and other coatings.

So although the Galvaprep is an excellent metal conditioner, it is not entirely necessary if you take the time to detergent clean the substrate.  Detergent rests on the alkaline side of the limtus scale.  So, when they often have an easier time reducing the residual that is remaining on the substrate of the galvanized metal.