October 10 - October 18, 2015
What are the criteria for selecting coatings for application during extreme (atmospheric) heat?
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Antonio Leal of IMMT-Institut Macaé Tecnology and Metrology on
October 23, 2015:
It's hard to answer this question without other information such as values and ranges of these temperatures, environments where they are located, such as marine, forest, or urban; and equipment usage limitations (Is it necessary to clean to Sa 3?).
Warren Brand of Chicago Coatings Group on
October 15, 2015:
Most paint and coating materials have a broad range of allowable application temperatures, which fall well within whatever ambient conditions one would find. As Jeremi pointed out, however, surface temperature is critical, although if you're using a polyurethane, the ambient humidity (or lack thereof) can be a serious factor. Lastly, if you're dealing with extreme heat, one would assume it's sunny out. THIS is of great concern. You can easily have one side of an asset exposed to direct sunlight with a surface temp of 140 F (which may be too high for application at all), where the other side (in the shade) may be 95 F. Lastly, the surface temp will have a profound impact on the recoat window, if you're using a multi-coat system. When we work on projects like this, whenever possible, we try to specify a single-coat system, or, if necessary, a compatible primer with a very long recoat window (which typically translates into a longer-than-typical recoat window with high temperatures).
Jay Barstow of Aeroflor Coating Services on
June 18, 2012:
Pot life for one (pre-cool). Heat can be good in that it reduces viscosity and increases wet-out, but if the substrate is concrete, trapped air can off-gas (coat in cool-down cycle), or solvents can flash off the surface too quickly, leading to entrapment (especially prevelant in windy conditions). Recoat window can be shortened significantly as well (check data sheet). In addition, my guys sweat on the substrates as well, which makes me none too happy.
Jeremi Day of Allphaz Inspection Services on
June 11, 2012:
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Surface temperature is what is used to determine service life, cure times, overcoat or recoat intervals, service compatibility, etc. Therefore, selection of coatings should be based on surface temperature rather than atmospheric temperature. The selection should, however, take into account the atmospheric temperature to identify pot life limitations, LEL limits, and the general characteristics of the coating and how it will react in certain atmospheric conditions, such as whether or not to use tropical cure formulations of the product as apposed to cold cure versions. More clarity to the question is needed, in my opinion.
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