70 degrees F and 50 percent relative humidity. For every 10 degrees C 18
degrees F rise in temperature, pot life is reduced by approximately half,
and for every 10 degrees C 18 degrees F drop, it is approximately doubled.
Usable pot life depends on the temperature of the material at the time of
mixing and the sustained temperature at the time of application. Other
factors such as the shape of the container and volume of mixed material may
also affect pot life. In hot climates, precooling or exterior icing of
components for at least 24 hours to a minimum of 10 degrees C 50 degrees F
will extend pot life. High humidity at the time of mixing and application
shortens pot life of the Modified PTFE-Pigmented Fluoropolyurethane
material. Following are approximate pot life times:
Sealant
As specified by manufacturer
Epoxy Primer and Intermediate Coat Materials
4 hours
Fluoropolyurethane Topcoat Material
3 hours.
3.10.1.4
Application Conditions and Recoat Windows
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NOTE: These requirements are provided in an attempt
to prevent the significant number of intercoat
delamination failures that are frequently found on
industrial structures. The very strict requirements
on application conditions and recoat windows may
require work during abnormal hours, including
weekends. Contractor work hours should allow for
such during coating application.
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NOTE: Cold-weather application is not covered by
this specification. If a project is designed for
coating in cold weather, then the enclosure and
heating requirements may be significant. It is not
intended that contractors be forced to apply
coatings in cold weather, however, the underlying
premise is that coatings must be applied within the
specified temperature ranges. A cold-weather
specification should not be used to simply save
money, as the coating system will generally not have
the same longevity as one applied within 60-100
degrees F.
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The application condition requirements for the coating system are very time
and temperature sensitive, and are intended to avoid the delamination
problems frequently found on industrial structures. Plan coating
application to ensure that specified temperature, humidity, and
condensation conditions are met. If conditions do not allow for orderly
application of sealant, primer, stripe coat, intermediate coat and topcoat,
use appropriate means of controlling air and surface temperatures, as
required. Partial or total enclosures may be required, as well as other
measures, to control conditions to allow for orderly application of all
required coats.
Apply coating only when steel and internal air temperatures are between 16
and 38 degrees C 60 and 100 degrees F. Do not apply coatings above 38
degrees C 100 degrees F or below 16 degrees C 60 degrees F.
SECTION 09970
Page 27
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