N804RV
Well-Known Member
Doesn't that kinda look like what happens with silicone contaminant?
Silicone makes “fisheyes” in the wet paint. Spraying again makes it worse. Wait till it dries and sand it off and start over. And never allow silicone in the paint shop again.Doesn't that kinda look like what happens with silicone contaminant?
This issue will turn out to be caused either by something similar, or something odd and unpredictable such as a nozzle material, air hose lining, unseen mist from a line leak.When I was at my old regional, they were buying new CRJs. Two had the whole side of paint blow off during a test flight. Back down to primer. They sent the guy in charge of that to the factory to investigate. One side of the plane painted by one person; the other had someone else. One side followed the instructions for the paint. The other side, the guy mixed it like he wanted. When our guy confronted him, he mixed up a batch in front of him like he wanted and said he could do it how he wanted and there was nothing they could do. Somehow there was some “protection “ that allowed it. He probably didn’t paint everyone of ours, but some would end up with strange peeling sometimes within the first year.
brings back memories of the Space Shuttle Challenger crash. the insulation of the external tank was changed to an environmentlally friendly chemistry that did not bond as well to the tank or itself and also had tendencies to have voids of unknown size, location, and distribution. An amazing push to develop an ultrasound technique/system that could accurately locate and define them was one of the reasons they were able to manage the risk to some degree when they returned to flight.No mystery here. One of the local mechanics told me it is the "environmentally friendly" paint they are now using.
during my decades in the Boeing labs, virtually all of us doing development of the "water borne" coatings saw over and over again how the new "friendlier" systems worked just as well as the older solvent borne systems when everything was perfect. However, the solvent borne systems were quite a bit more tolerant of imperfection in the prep and application processes...and adhesion was more reliable.No mystery here. One of the local mechanics told me it is the "environmentally friendly" paint they are now using.
another thing we showed in the labs at Boeing was the phenomenon of finish system film cracking "growing" down into the substrate matrix in the laminates.As Pops said, thicker coatings have more forces driving system cracking and all cracks allow foreign elements into the bondline at the structural surface.If paint is too thick it can crack like a dry lake bed as it shrinks over time.
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