What is a wet storage stain?

A wet storage stain is a white, rust-like surface discoloration that occurs from storing newly hot-dip galvanized materials.  Wet storage stains occur when recently hot-dip galvanized materials are subjected to a moisture-rich environment and/or the materials are packed so closely together that there is not enough air movement and oxygen for the parts to “breathe”.

When storing hot-dip galvanized materials it is optimal to store the material in a warehouse or covered area that limits exposure to moisture.  It is also important to store the material with gaps between each part to allow for air circulation using wood spacers and stacking techniques that prevent the parts from having surface to surface contact.  For jobsite storage, avoiding direct contact with earth or vegetation is important, but also stacking or storing the galvanized items with an purposeful decline that allows for drainage so moisture does not accumulate.

Materials that have been exposed to moisture and have developed wet storage stains are not in a condition to be sold again to a new customer and cannot be returned to Portland Bolt.  This condition isn’t desirable for a new customer due to the aesthetic look of the stain, but more importantly the wet storage stain does not allow the zinc layer to develop the zinc patina that actually protects the galvanized part.  It is very important to avoid wet storage stains on newly galvanized materials before the material gets a chance to develop the normal layers of corrosion protective zinc patina.

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