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Parker’s Smith Coating Solution Zinc Runoff from Galvanized Roofing

Problem: Non-Compliant Zinc Run-off from Galvanized Roof

25,000 sq. ft. galvanized zinc roof with 3/12 pitch exhibited an unacceptable amount of zinc oxide in the run-off and various locations on site. The state of Oregon performed testing and determined there were unacceptable levels of zinc. They mandated that the asset owner mitigate the condition
or replace the roof.

Solution: Parker Smith’s Metal Roof Painting System

Prepare and coat the roof with a two-coat system by Induron Protective Coatings to mitigate the run-off via encapsulation.

Our Process

Wash the roof with potable water at high pressure (2500-3000psi) to remove any contaminates and capture run-off water.
Dry abrasive blast roof using a 350 CFM compressor and #4 Venturi blast nozzle with 30-60 recycled glass abrasive as per SSPC SP-16, Society of Protective Coatings Surface Preparation method 16.

Non-Ferrous Brush off Blast achieves a 0.75 mil angular profile to promote adhesion and give a sound substrate to apply coatings.
Apply one coat of 85% Solid Induramastic 85 Epoxy Mastic at a dry film thickness of 6-8.5 with a Titan 1140 electric airless sprayer utilizing a 50’ x 1/4” hose and RAC 5 517 airless spray tip.

To measure thickness, the team used a wet film thickness gauge. These gauges quickly measure the thickness of coatings after application. As per SSPC PA-2 standards, they also used a type 2 dry film thickness gauge to measure the dry film thickness.
After 1 to 3 days of cure at ambient conditions, Smith’s team applied a second coat of Indurethane 660 aliphatic acrylic polyurethane at a thickness of 5-6 mils wet. The process included measuring both wet and dry as per SSPC PA-2 to ensure the correct total dry film thickness.

Methodology

Dry abrasive blasting is the best way to prepare a non-ferrous surface to accept coatings.

High Solid epoxy mastics promote adhesion as well as providing barrier corrosion protection.

Aliphatic polyurethanes achieve color and gloss retention for exterior exposures. According to ISO 12944, this system’s preparation level supplies a service life of 15 to 20 years.

Results

The asset owner is now in compliance with state and federal regulations without the need to remove the existing roof or shut down operations in any way during the project preparation and coating application.