10 YEARS’ EXPOSURE AT HENDAYE, FRANCE.
Severe marine environment dramatically confirms the superior performance of the 55% Al-Zn substrate
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55% Al-Zn
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Galfan
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Hot-dip galvanised
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45º South: polyester coatings. The Galfan (Zn-5%
Al) and hot-dip galvanised panels show paint loss along the edges, white
corrosion along the bend, and blistering. The 55% Al-Zn panel remains
in excellent condition.
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55% Al-Zn
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Galfan
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Hot-dip galvanised
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5º South: polyester coatings. Realistically replicating
a building roof in this severe marine environment, these panels with 10
years’ exposure clearly show the excellent performance of 55% Al-Zn.
The 55% Al-Zn panel has no detectable edge creep rusting or blisters and
just a little staining on bends and edges. In stark contrast, the Galfan
and hot-dip galvanised panels show edge creep that exhibits the total
dissolution of the underlying substrate’s metallic coating, with
paint loss and rust on the bends and flat surfaces. There is severe corrosion
along the bend, and severe blistering in flat and formed areas and around
fasteners is also obvious.
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55% Al-Zn
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Galfan
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Hot-dip galvanised
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90º North: polyester coatings. This area replicates side walls with the longest time of wetness, with an overhang providing a sheltered area. The 55% Al-Zn panel shows virtually no failure, proving the product’s excellent sheltered area corrosion resistance.
Both the other panels (the hot-dip galvanised shown here
is coated with silicon modified polyester) show extensive substrate corrosion
and paint loss on edges, bends and flat areas.
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55% Al-Zn
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Galfan
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45º South: Pvdf coatings. Both these panels, coated
with the fluorocarbon paint system, show good performance, although some
paint loss is seen along the edges of the Galfan panel, and a few blisters
are visible on the bend.
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55% Al-Zn
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Galfan
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5º South: Pvdf coatings. This more aggressive orientation
causes problems for the Galfan panel, with loss of paint adhesion along
the sheared edges, and blistering on the bend and flat areas. The 55%
Al-Zn panel remains free of any significant failure: there are fine blisters
along the edge, but they have not developed and the paint still adheres
to the substrate.
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55% Al-Zn
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Galfan
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90º North: Pvdf coatings. The strong sheltered area corrosion resistance of 55% Al-Zn is again clearly shown, demonstrating its all-round relative superiority