Which side out?

[Studioman]

I haven't pulled back the plastic protective cover on the .032, but last night I put a piece of .025 on the belly pan and noticed the "writing" on the protective cover soaked through and seems to have bled into the aluminum.

The "writing side" seemed a little nicer, but it was hard to be for sure, even after close examination.

I'll be starting the repair on the skin in the next couple of days.

My question:::

Which side of the aluminum goes outside?

[vinstream]

In most cases the writing is the side that goes out, the only exception to this is what they call "critical surface" spec material. This may seem strange for those outside of the metal industry but writing, or stencil as it called in the industry, states material (3003, 5052, 6061, 2024) temper (H-32, T-3), thickness (.025, .032, .040) and codes that may include where the material is manufactured or processed. All this information is critical to the manufacturing process. All of these materials come off a giant roll or coil and then leveled in a leveling line and the stencil coming off the coil is all ways on top and the PVC is place on top as it leaves the leveling head so that is why the PVC is on top or over the stencil markings. The stencil markings are inked on and the best thing to remove them is with rag with MEK and lightly wipe. If you are going to polish the stencil will polish right off. In the photos you will see a leveling line in action and a stenciled sheet of aluminum with the type of information stated above. Hope that helps...

[Mixter]

I didnt completely follow that...

If its Alclad, does it matter? I was under the impression Alclad is on both sides- (maybe dipped???)

I dont think I've paid attention when patching some of the Alclad, thinking it was same on both sides... Hope I didnt mess up!

Mic

[truckasaurus]

I'd say the opposite. I have never seen an aircraft repair or shop made part with the stencilling on the outside face unless it's by mistake.

[vinstream]

Originally Posted by Mixter

I didnt completely follow that...

If its Alclad, does it matter? I was under the impression Alclad is on both sides- (maybe dipped???)

I dont think I've paid attention when patching some of the Alclad, thinking it was same on both sides... Hope I didnt mess up!

Mic

Alclad is on both sides of 2024 material... The stencil is always on the outside of the coil and the PVC is layed on over it. Sure you can flip the panel over to the none stencil and PVC side but why when it is protected.

[vinstream]

Originally Posted by vinstream

Alclad is on both sides of 2024 material... The stencil is always on the outside of the coil and the PVC is layed on over it. Sure you can flip the panel over to the none stencil and PVC side but why when it is protected.

Most places sell 2024 with paper interleaf and not PVC so most aircraft repair shops by bare aluminum with no PVC and place the stencil inward; However, standard building practice with sheet products is that the stencil out because that is the nicer or cleaner of both sides after it goes through the leveling process...

[Studioman]

I didn't mean which side is the writing on when it's made, I meant which side to have facing out when installed on a camper, plane, etc.
I put a 7'x 19" piece of .025 on the belly, I out the non-writing side out as to me, that side appeared "Smoother".

Vinstream: The Alcoa 2024 T3 has PVC (At least some kind of plastic) on BOTH sides of the material.

I'd like to cut my .032 today, but it's MUCH MORE important that I get the correct side facing out as I make the cuts.

I'm really glad I started on the underbelly, I am learning SO MUCH about working with the material. WAY different than metal, I can now verify that!

But, that dent came out pretty decent, but I am changing out that part of the panel anyways...

Thanks again if anyone knows for certain which side faces out on the installation (NOT the manufacturing process)???

[truckasaurus]

Studioman. My post was based on my experience in aviation. I am a licensed aviation structure engineer, I learnt why and how to work with this material in a great school and have worked for a well known airline that operates a decent sized fleet globally. There is no reason to have to text facing outside at all. Hope this helps. Note maybe its different in the rv world but I doubt it.

[Studioman]

Structurally, I knew it didn't matter.
I meant more for polishing.
This morning, I took a really good look at the .016 piece I got (For some decorative stuff inside). And the writing side DOES have a lot less scratches. But the "lines" seem about the same.
I'm only worried about keeping polishing to a minimum.
I need to transport my .032 after I make the rips, so I really don't want to pull back to much of the plastic covering off of whichever side I am leaving to the outside.

[vinstream]

Studioman, if it has PVC on both sides then it does not matter. Just be careful to not leave the PVC on with direct sunlight, The UV seams to bond the PVC on that its almost imposable to take off. The least scratched side will be the stenciled side. In terms of Polishing you still need to compound the aluminum before you polish it to get a true mirror finish. Looks like you on the right track!