How To Remove Zinc Corrosion Residue From Stored Steel Roofing Panels

If you or your company have stored steel roofing panels under tarp in a humid climate for even a short period of time, you might remove the tarp and find some odd white powder along the edges and ridges. This white powder, which resembles a light-colored rust, is due to the moisture corroding the zinc present in the steel's protective coating. As long as the corrosion hasn't caused any actual structural damage, the cleanup process is relatively simple and should have you placing the roofing panels on schedule.

Things You Need:

  • Steel roofing panels
  • Clean rag
  • White vinegar
  • Scrub brush
  • Water-based paint and/or sealer

Step 1: Clean the Powder Off

Lay out a steel roofing panel flat on the ground. Soak a clean rag in ordinary white vinegar. Dab the rag along the edges and ridges where the white powder appears. Use a scrub brush to gently exfoliate the powder off of the panel. Work slowly and carefully to avoid scuffing up or causing damage to the panel.

Note that if the powder is covering a large area you will want to apply the vinegar to an area about a foot or two wide then use the brush on that section. Don't move on until one section is completely cleaned. Allow the cleaned panels to dry overnight.

Step 2: Protect the Panels

If you're beginning your construction project with unprotected panels that have already experienced corrosion, you will want to coat the panels before work begins. This stops the corrosion from setting in again once the panels are already on the roof where it's much harder for you to work carefully with vinegar and a scrub brush to clean off the white powder.

Use a water-based paint with a built-in primer or a water-based sealer on all of the steel panels. The water repelling formula will keep away the moisture that promotes zinc corrosion and allows you to work more slowly and carefully despite the panels being exposed to humid weather during construction.

Step 3: Improve Your Storage Practices

If you need to put some of the protected steel panels back into storage, they should be safe from the elements. But you might need to store new, unprotected steel panels again in the future. The white powder was caused by a combination of heat, humidity, and a lack of ventilation. Access your storage practices for metal roof material and see which of these qualities were present and adjust accordingly.