Can I field paint galvanized deck? My first attempt peeled right off!

Yes you can, but it might not be easy!

painting galvanized deck failureWhy did my paint peel off? Years ago, steel mills began adding a standard chemical treatment to coils to prevent white rust, also known as “wet storage stain.” More recently, these mills have changed the chemical formula to make the treatment less caustic. This new formula, however, can prevent proper adhesion of paint to the galvanized surface. If you need to field paint galvanized steel deck (such as composite floor deck) that was not special-ordered for painting, your only sure option is to attempt to remove the chemical treatment by sandblasting it off without being too aggressive and also removing the galvanizing (zinc coating).

 

Can I order galvanized steel deck that won’t require sand blasting? Yes you can! There are two options you have at the time you order your steel deck.

  1. The best option is to order your steel deck with a galvanized AND prime painted coating. The material will arrive at the job site with a shop-applied primer coat over the galvanized base steel. This will allow you to begin with a properly-adhered primer. (D-MAC has this type of deck in stock!)
  2. You could ask the manufacturer to use coils without the standard chemical treatment. While you will not have to sand blast the chemical treatment off of the deck, you may have to clean off white rust that will now form more quickly without the chemical protection.

I have deck on site that has a shop-applied primer. What else should I know before I paint it? The Steel Deck Institute offers the following procedure for field painting:

  1. Check with the paint manufacturer for any special recommendations.
  2. Make sure all surfaces are clean, dry, and free of grease and dirt.
  3. Test a small area to assure compatibility and proper adhesion.
  4. Apply paint following the paint manufacturer’s instructions.

If you have any questions about field painting deck, or any other technical issues, please feel free to ASK D-MAC!