Over blasting

This is an example of a galvanized surface that has been over-blasted.  The over-blasting can occur when the pressure is too high, angle of blast too steep, blast media too aggressive or the venturi setting too high.  The force of the impact from the blast media strips off the galvanizing.  It is often seen on bends or corners where the pressure is concentrated.  With continued blasting these edge tears grow as the blast media gets under the coating.    Blasting is usually recommended to be done at 40psi and an angle of incidence of 45degrees.

If the individual areas are under 40 square centrimeters then this can be repaired by using a zinc rich primer.  If they are larger then they need to be returned for stripping and re-dipping and this will be to the fabricator/blasters cost.

peeling, flaking, stripping, delaminating, flakes

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