Hello folks! I've done some searching around about this, and I also called Van's builder assistance for an official opinion, and picked up some interesting tidbits along the way.
I had some normal scratching from chips, assembly, etc., on the inside of my horizontal stabilizer skins, and I wanted to know if they were deep enough to require sanding. Pictures and the full discussion are available here - http://rvhaslanded.blogspot.com/
However, here's the summary of my conversation from Van's builder assistance:
Question: I have some scratches caused by drilling and temporary assembly. How do I know when they are deep enough to warrant sanding?
Answer: When you can catch your finger nail in them.
Question: Should I prime the mating surfaces?
Answer: This is often debated, but we recommend that you prime only the mating surfaces, if that. The inside of the skin, rib webs, etc., don't hold water, so there is almost never a corrosion issue on non-mated surfaces.
Question: It's easy to tell that the big skins are AlClad (it's printed on the aluminum), but how can I tell for the smaller parts like ribs? Is it indicated on the parts list?
Answer: No, but it's easy to tell. Anything .040" or thinner is certainly AlClad, because all [Van's] sheet aluminum is AlClad. So, ribs, angle, etc. bent or formed from sheets is AlClad. Extruded parts, such as extruded angle, stiffeners, etc., are not AlClad.
This was very helpful. As a result, I intend to only prime mating surfaces and the extruded parts. Since this is self-etching (DupliColor) primer, I think I am going to skip the sanding step, because I don't see the purpose in removing the AlClad to get better adhesion. I figure it'll stick well enough in the scratches where it needs to.
Other opinions? I'm glad to hear them!
I had some normal scratching from chips, assembly, etc., on the inside of my horizontal stabilizer skins, and I wanted to know if they were deep enough to require sanding. Pictures and the full discussion are available here - http://rvhaslanded.blogspot.com/
However, here's the summary of my conversation from Van's builder assistance:
Question: I have some scratches caused by drilling and temporary assembly. How do I know when they are deep enough to warrant sanding?
Answer: When you can catch your finger nail in them.
Question: Should I prime the mating surfaces?
Answer: This is often debated, but we recommend that you prime only the mating surfaces, if that. The inside of the skin, rib webs, etc., don't hold water, so there is almost never a corrosion issue on non-mated surfaces.
Question: It's easy to tell that the big skins are AlClad (it's printed on the aluminum), but how can I tell for the smaller parts like ribs? Is it indicated on the parts list?
Answer: No, but it's easy to tell. Anything .040" or thinner is certainly AlClad, because all [Van's] sheet aluminum is AlClad. So, ribs, angle, etc. bent or formed from sheets is AlClad. Extruded parts, such as extruded angle, stiffeners, etc., are not AlClad.
This was very helpful. As a result, I intend to only prime mating surfaces and the extruded parts. Since this is self-etching (DupliColor) primer, I think I am going to skip the sanding step, because I don't see the purpose in removing the AlClad to get better adhesion. I figure it'll stick well enough in the scratches where it needs to.
Other opinions? I'm glad to hear them!
