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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 ambient air and steel temperatures are between 16
and 38 degrees C 60 and 100 degrees F, and steel surface temperature is
more than 3 degrees C 5 degrees F above the dew-point of the ambient air
during application and the first four hours for epoxy and the first eight
hours for polyurethane. Do not apply coatings above 38 degrees C 100
degrees F or below 16 degrees C 60 degrees F.
Use Table entitled "RECOAT WINDOWS" to determine appropriate recoat windows
for each coat after the initial coat. Apply each coating during
appropriate RECOAT WINDOW.
If coating is not applied during RECOAT WINDOW, apply during EXTENDED
RECOAT WINDOW. Application of any epoxy coat within the EXTENDED RECOAT
WINDOW requires application of a TACK COAT prior to applying any full coat.
Perform cure test immediately prior to application of TACK COAT to
determine condition of applied coating. If CURE TEST indicates that
surface is fully cured, provide GLOSS REMOVAL prior to application of TACK
COAT.
If coating is not applied during EXTENDED RECOAT WINDOW, or if surface
temperature exceeds 49 degrees C 120 degrees F between applications, wash
surface with water and detergent, rinse clean with fresh water and allow
surface to dry thoroughly, provide GLOSS REMOVAL, apply TACK COAT, where
applicable, within 24 hours, and apply next full coat within TACK COAT
RECOAT WINDOW.
RECOAT WINDOWS
EPOXY OVER EPOXY
Temperature degrees F
60-70
71-80
81-90
91-100
101-110
111-120
Temperature degrees C
16-21
22-27
28-32
33-38
39-43
44-49
RECOAT WINDOW
24-72
18-60
16-48
12-36
8-18
4-6
(Hrs.)
EXTENDED RECOAT
72-168
60-140
48-120
36-96
18-36
6-12
WINDOW (Hrs.)
TACK COAT RECOAT
6-72
4-60
4-48
3-36
2-18
1-6
WINDOW (Hrs.)
POLYURETHANE OVER EPOXY
Temperature degrees F
60-70
71-80
81-90
91-100
101-110
111-120
Temperature degrees C
16-21
22-27
28-32
33-38
39-43
44-49
RECOAT WINDOW
24-96
24-72
16-48
12-36
10-24
8-16
(Hrs.)
EXTENDED RECOAT
96-168
72-144
48-120
36-96
24-48
16-24
SECTION 09971
Page 27
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