On Sunday, November 15, 2015 at 5:24:23 PM UTC-5, wrote:
PU does seal that surface up better, mostly because it seals up the porosity in the gelcoat as well as being a much better UV barrier.
UH

UH...Curious as to the factory steps taken to apply a PU finish. Is everything the same (same gelcoat, same thickness, same sanding, same prep, et cetera sans waxing) then the wing is taken to a paint booth and sprayed like a car?

After spray painting, are the wings sanded or "rubbed" in any way?

What is the current "favorite" maintenance wax or polish for factory finished PU?

Thanks for your response.

I used to work in the paint shop at schempp-hirth.

the two processes are different.

What they do for paint is this: they apply a thin layer of molding gelcoat to the molds. it provides excellent adhesion to the composites, and releases from the mold nicely. when the fuse/wing/whatever is pulled from the mold, the thin layer of molding gel-coat is scuffed with sandpaper. at that point they then spray urethane primer, wetsand it, then do a PU topcoat, wetsand it. then its ready for trim stripes/ decals and polishing. after any striping, they also offer clearcoat to remove the lip edge of any decals/contest letters et cetera. but that's only applied in the local area of the decal.

With gelcoat, after the mold they just spray gelcoat onto the scuffed molding gelcoat.