Method and Results
Method:
After thermal cycling, all ten test panels
were placed in a Seawater Spray (Fog) Chamber, ASTM B117,
for 500 hours (3 weeks). The Salt Water Spray Test is considered
to be the toughest weathering test that a coating can undergo.
The chamber was operated in accordance with the procedures
set forth in ASTM B117, except actual sea water was used in
place of standard salt water. This provides a more natural
and realistic scientific test. Salt spray is a natural phenomenon
in seaside and seagoing environments and is also of interest
to automobile owners in northern climates where the roads
are salted in the winter to melt ice. To simulate these conditions,
seawater is atomized with a special device and allowed to
condense in an even manner on the surface of the test panels.
It combines the corrosive effects of sea water with the oxidizing
effects of oxygen dissolved from the air by the water droplets.
Additionally, it provides an erosive wash condensation and
flow over the coating surface. Keep in mind, these panels
have already been X-scribed, been through 300 hours in the
Weatherometer, and Thermally cycled as described earlier.
The length of exposure for the Seawater Spray Test is specified
by the United States Navy’s standards, which is 300
hours below deck and 500 hours above deck. |
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| Results: The Rust Bullet® panel (number 2), the Rust-oleum® Cold Galvanizing Compound panel (number 5), the Wasser® Brand System panel (number 6), and the POR-15® System panel (number 8), exhibited corrosion along the scribe lines with undercutting of less than 3/16 of an inch. The Rust-oleum® Rusty Metal Primer panel (number 1), the Rust-oleum® Rust Reformer panel (number 3), the Zynolyte Urethane with Zinc-Chromate Primer panel (number 4), the Naval Jelly® Rust Neutralizer panel (number 7), and the Hammerite® Rust Cap panel (number 9), exhibited coating failure over the entire surface of each panel. These panels were considered complete failures and were eliminated from further testing. The uncoated control panel (number 10) was so severely corroded it was of no further value and was also eliminated. Printed from National
Testing Standards, Inc., Report: Method: After thermal cycling
all ten test panels were placed in a salt fog/spray chamber
for 500 hours (3 weeks). The chamber was operated in accordance
with the procedures set forth in ASTM B-117 except actual sea
water was used in place of standard salt water. |
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