Proper cleaning and pretreatment of metals is critical to the high-performance paint finish used for panels. For proper long term performance of coatings, metals must be cleaned of contaminants left behind from the processing and manufacturing cycle. Pretreatments are used to convert the metal surface into a non-metallic coating. This ensures proper adhesion by a chemical/physical bond, and enhances the durability of both the base metal and paint finish by providing an additional protective barrier for areas where the paint is prone to damage.

There are numerous pretreatment applications available, and the performance of each varies depending upon the type of metal, the overlying paint system and the geographical area where the metal roof panels are installed.  Most locations are identified as rural, industrial, marine or severe marine environments.

The most commonly used pretreatments for metal panels are as follows:

Complex Oxides

– hot dip galvanized steels

Complex Oxides provide excellent flexibility in the forming operation of steel panels.  “Generally this type of pretreatment is not formulated to provide additional barrier protection and steel surface conversion in environments subject to acid rain, industrial chemicals and fumes or marine and severe coastal locations.”

Zinc Phosphates

– hot dip galvanized steels

Zinc Phosphates typically provide increased corrosion resistance of galvanized steels by the surface conversion during the pretreatment process.  Used commercially for over 100 years, Zinc Phosphates have undergone numerous evolutionary improvements. The use of additives and refinement of the process has increased the durability of steel roofing panels with difficult forming requirements.  If the galvanized steel roof panel is subject to aggressive environments such as acid rain, industrial chemicals, fumes, or severe coastal locations, this pretreatment is commonly recommended.

Complex Chrome Oxides

– aluminum/zinc alloy coated steels and aluminum

Available as conversion coatings as well as dry-in-place coatings, Complex Chrome Oxides have been used extensively on both aluminum/zinc alloy coated steels and aluminum. The advantages to Complex Chrome Oxides include excellent formability, and field-proven corrosion resistance to the base metals.

New emerging technologies are forthcoming in the metal pretreatment industry, including chrome-free alternatives for commercial applications. Advanced technologies are being developed to improve the performance of pretreatments while offering cleaner methods with minimized environmental impacts. Existing technologies combined with emerging trends adds to the environmental appeal of metal roof systems and their long life performance compared to other roofing materials.

Due to the varying types of base metals, pretreatments, and paint systems used, building owners should consult with their metal roof supplier to ensure all aspects of the coating system are considered prior to material selection.

Bulk Bond® Products

3110 – HDG – Non Building Products

3000 – Aluminum & Galvalume

312 – HDG – Building Products

780 – CRS

NP – 250 – Dried in Place Treatment

Bulk Kleen® 

845P – Cleaners

Bulk Rinse® 

6A – Chrome Sealers

Find additional Bulk product information here