Coating Weathering Steel

[facca]

We completed the coating of a weathered steel bridge using conventional blasting of the steel and meeting the proper profiles to paint a 3 coat epoxy zinc coating. The paint is now starting to fail.Is weathering steel meant to be painted. Any advice would be helpful.

 

[coatingengineer]

Hi,

Applying coatings under variable atmospheric condition always presents challenges. Grit blasting, you know, is always wise -- both for an adhesive anchor-pattern and for rust-oxide removal.

Your choice of an epoxy, zinc-rich coating sounds ideal. If its failure, loss of adhesion, seems premature, take a closer look at your environment. Then speak with your coating manufacturer.

For example, how UV stable (ultra violet light) is the coating? Is atmospheric temperature exceeding the thermal stability of the coating? (Depending on color, black for example, there is always the 'black body effect'.) What about flexural strength of the coating, compared with the steel beneath?

My expertise is typically associated with preventing wear, friction, corrosion or sticking -- mainly indoor, dynamic environments:

http://www.industrialcoatingsworld/Corrosion-Resistant-Coatings/index.html

Nevertheless, look to the following companies and products for help:

Heresite Protective Coatings
Wearlon Coatings (now known as Environmental Coatings)
PPG (their version of PVDF, polyvinylidene fluoride)

Best wishes,

William Gunnar
Industrial Coatings World









William Gunnar

http://www.IndustrialCoatingsWorld.com