vic syracuse
Well Known Member
As I mentioned earlier, since I am getting ready to apint soon, and I have had the blisters on 2 of my past QB's, I am really anxious to not have this happen again. So, I'be been "'sperimenting" over the last few weeks with some different solvents, and I have noticed a few things.
First, I always have final cleaned with acetone prior to acid etch primer, so I did the same with my 2 RV-10 QB tanks now. After a couple of days, I noticed some weeping contamination around 60%-80% of the rivets. I can't tell what it is, other than to say it looks like a slight film contamination, almost like a water stain, and it does grow as time passes to around 2 diameters of the rivet head, and is not always perfectly round.
So now, I have also celaned them with Dupont Prepsol (which is really mineral spirits), and MEK. There is almost no contamination evident with these 2 cleaners after a couple of days, but I will wait until the week end to declare victory.
On the RV-7 which is beginning to look absolutely terrible, there aren't any fuel stains underneath the blisters. When they do pop, it looks like an adhesion issue with the paint/primer. Carol and I do actually remember this same kind of phenomenon (weeping film) when we painted them, but really didn't think much of it at the time. We just rewiped, and then shot the primer.
I noticed that our QB parts have some kind of oil on them when received from VAN's. I've assumed it is some kind of protectant for the overseas journey. I noticed that I saw this same kind of weeping on the screw holes on the tank where I had not cleaned them well enough, and it got me to thinking that perhaps the oil is reacting or absorbing into the proseal and weeping out over time, causing the adhesion issue. Since it doesn't occur anywhere else on the airplane, I'm thinking it could be related to the proseal, but for different reasons than have been suggested, such as an improper mix, especially since there doesn't appear to be fuel underneath the affected rivets. Of course, perhaps an improperly mixed proseal works good enough to be leak free, but can still aborb and weep contaminants on the surface.
Vic
Vic
First, I always have final cleaned with acetone prior to acid etch primer, so I did the same with my 2 RV-10 QB tanks now. After a couple of days, I noticed some weeping contamination around 60%-80% of the rivets. I can't tell what it is, other than to say it looks like a slight film contamination, almost like a water stain, and it does grow as time passes to around 2 diameters of the rivet head, and is not always perfectly round.
So now, I have also celaned them with Dupont Prepsol (which is really mineral spirits), and MEK. There is almost no contamination evident with these 2 cleaners after a couple of days, but I will wait until the week end to declare victory.
On the RV-7 which is beginning to look absolutely terrible, there aren't any fuel stains underneath the blisters. When they do pop, it looks like an adhesion issue with the paint/primer. Carol and I do actually remember this same kind of phenomenon (weeping film) when we painted them, but really didn't think much of it at the time. We just rewiped, and then shot the primer.
I noticed that our QB parts have some kind of oil on them when received from VAN's. I've assumed it is some kind of protectant for the overseas journey. I noticed that I saw this same kind of weeping on the screw holes on the tank where I had not cleaned them well enough, and it got me to thinking that perhaps the oil is reacting or absorbing into the proseal and weeping out over time, causing the adhesion issue. Since it doesn't occur anywhere else on the airplane, I'm thinking it could be related to the proseal, but for different reasons than have been suggested, such as an improper mix, especially since there doesn't appear to be fuel underneath the affected rivets. Of course, perhaps an improperly mixed proseal works good enough to be leak free, but can still aborb and weep contaminants on the surface.
Vic
Vic