Selected Answers

From Trevor Neale of Blastco on May 5, 2020:
I agree with previous answers but also require tha ...read more I agree with previous answers but also require that at least 10 samples of each variant are exposed. A further variant to cover more of the bases that coating are exposed to is that the application must be carried out at a work site typical of the exposure conditions for which the system was designed. I have little faith in in single panel lab tests when evaluating coating systems designed for exterior or in-plant exposures. Finally, since the tests typically take many months or years to be of true value, a regular inspection program is mandatory.

From Mike Beitzel of Modjeski and Masters on April 28, 2020:
Neil, I am with you, but I would take it an additi ...read more Neil, I am with you, but I would take it an additional step and add a third panel that has been pitted and corroded and then cleaned and oriented horizontally to simulate a more realistic re-coated surface with extended water exposure in the corroded and pitted areas; and some thought should be given to adding welds and edges to the test panels, similar to the panels NACE uses in their CIP program for practical blasting and painting experience.

From Neil Pittman of Lake Superior Consulting on April 28, 2020:
There should be two panels, one scribed, and one n ...read more There should be two panels, one scribed, and one not. The scribed panel can be evaluated for rust creep, and the unscribed panel can be evaluated for gloss, DOI, blisters, and other visual evaluations. Test panels take a long exposure to reveal differences in coating systems, so why not do both?