Storage Stain

All metal cladding and accessories should be kept dry before installation, including during storage on the roof structure, because accelerated corrosion or staining can occur with all metals if close stacked cladding or packing becomes wet.

If zinc coated nestable profiles have become wet while closely stacked, either in transportation or storage, the formation of wet storage stain or white rust is inevitable. AZ coatings are mill coated with an acrylic passivation film to give temporary protection and minimise the possibility of product deterioration. Pre-painted sheets will also deteriorate if they remain wet as moisture can cause paint softening and sheets may exhibit paint bubbling.

Aluminium, copper, zinc and stainless steel will all be permanently stained if left wet or if stored in this condition. Translucent cladding and all metal roofing accessories with a strippable film should be protected from direct sunlight.

If moisture is present, individual sheets should be dried and then re-stacked to allow air to circulate and complete the drying process.

The extent and severity of wet storage stain is usually proportional to the length of time the sheeting has been wet.

In the case of superficial attack, exposure to the atmosphere and careful cleaning will sufficiently reduce surface imperfections, but heavier deposits can damage the sheets to the extent that they require replacement.