Urethane Paint

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.

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.

Good to know...thanks ND.

How thick do you recon they get the PU topcoat? I know the PPG Concept we've use recommends two wet coats of 3 mils each for a total of 6 (this is for their standard auto applications). This then dries to a very thin (1-1.5 mils). We were able to get thicker coats for maybe 8-9 mil wet which seemed to give us (barely) enough material to color sand (wet sand). The automotive guy who did the Urethane paint couldn't understand why in the world we'd want to mess up his perfectly good spray job (with only very minor orange peel) by sanding!

As a sidebar... now that I've messed with this stuff, I can't help but look carefully at every car I see in the parking lot. I was looking at a Mercedes GLK the other day which had what glider guys would consider "bad" orange peel on a factory finish. On the other hand, from a work perspective, it's much more efficient to just "spray and forget it".

p3

On Monday, November 16, 2015 at 4:59:07 PM UTC-5, Papa3 wrote:
How thick do you recon they get the PU topcoat? I know the PPG Concept we've use recommends two wet coats of 3 mils each for a total of 6 (this is for their standard auto applications). This then dries to a very thin (1-1..5 mils). We were able to get thicker coats for maybe 8-9 mil wet which seemed to give us (barely) enough material to color sand (wet sand). The automotive guy who did the Urethane paint couldn't understand why in the world we'd want to mess up his perfectly good spray job (with only very minor orange peel) by sanding!

As a sidebar... now that I've messed with this stuff, I can't help but look carefully at every car I see in the parking lot. I was looking at a Mercedes GLK the other day which had what glider guys would consider "bad" orange peel on a factory finish. On the other hand, from a work perspective, it's much more efficient to just "spray and forget it".

p3

welcome to my world. orange peel will be my death at last. i see it on everything.

On Thursday, November 19, 2015 at 3:13:45 PM UTC-5, ND wrote:
On Monday, November 16, 2015 at 4:59:07 PM UTC-5, Papa3 wrote:
How thick do you recon they get the PU topcoat? I know the PPG Concept we've use recommends two wet coats of 3 mils each for a total of 6 (this is for their standard auto applications). This then dries to a very thin (1-1.5 mils). We were able to get thicker coats for maybe 8-9 mil wet which seemed to give us (barely) enough material to color sand (wet sand). The automotive guy who did the Urethane paint couldn't understand why in the world we'd want to mess up his perfectly good spray job (with only very minor orange peel) by sanding!

As a sidebar... now that I've messed with this stuff, I can't help but look carefully at every car I see in the parking lot. I was looking at a Mercedes GLK the other day which had what glider guys would consider "bad" orange peel on a factory finish. On the other hand, from a work perspective, it's much more efficient to just "spray and forget it".

p3

welcome to my world. orange peel will be my death at last. i see it on everything.

Orange peel and grey shadows. As one goes, other comes.
Gloom
UH

Modern cars finish is all some degree of orange peel.

It uses a lot of very expensive paint to block and finish an entire
glider to a zero imperfection state. Did I mention the days and days of
patient marker coat eradication...

But it DOES look pretty when you are done.

On 2015-11-19 22:13, ND wrote:
On Monday, November 16, 2015 at 4:59:07 PM UTC-5, Papa3 wrote:
How thick do you recon they get the PU topcoat? I know the PPG Concept we've use recommends two wet coats of 3 mils each for a total of 6 (this is for their standard auto applications). This then dries to a very thin (1-1.5 mils). We were able to get thicker coats for maybe 8-9 mil wet which seemed to give us (barely) enough material to color sand (wet sand). The automotive guy who did the Urethane paint couldn't understand why in the world we'd want to mess up his perfectly good spray job (with only very minor orange peel) by sanding!

As a sidebar... now that I've messed with this stuff, I can't help but look carefully at every car I see in the parking lot. I was looking at a Mercedes GLK the other day which had what glider guys would consider "bad" orange peel on a factory finish. On the other hand, from a work perspective, it's much more efficient to just "spray and forget it".

p3

welcome to my world. orange peel will be my death at last. i see it on everything.


--
Bruce Greeff
T59D #1771