"Exfoliation" on inside of aluminum panels

[beckettnole]

Hi All:

I am doing a full restoration and I am told that I have "exfoliation" on the inside of the exterior panels(pictures included)

Any recommendations I can do to mediate this issue?

Thank you!

Ryan

[xrvr]

Year and model?

[Protagonist]

What you're seeing appears to be aluminum oxide, the aluminum version of rust.

WD-40 and a nonmetallic abrasive pad like you use for cleaning pots and pans, plus plenty of elbow grease, should remove it.

But fair warning, if you remove the oxidation and don't remove the cause, it will come back. Also, underneath that grayish-white oxidation there is pitting of the metal and that pitting can be deep; the aluminum in aluminum oxide has to come from somewhere. No matter how much you polish it, the metal will still be pitted.

[beckettnole]

@avionstream it is a 1965 international sovereign about 30ft in length

Thank you for the advice....I was also told acrylic R to seal outside of panels ......then to repair any bad rivers......then acetone and/or a fine sandpaper to take away oxidation.....I bought Trempro 635 polyurethane from Vintage trailer to then finally seal the inside of the panels

I was warned also that it may be impossible to stop long term so any advice on anything additional that will mitigate/slow/stop it would be greatly appreciated


Warm Regards

Ryan

[Aerowood]

Bead blasting will remove any and all traces of the corrosion. Any corrosion in between the mating surfaces will also have to be removed or all your work removing the visible corrosion is a complete waste of time. Be prepared to blast through the skin if its really bad, in which case patching or replacement will be required. Corrosion if this type is caused by moisture setting up an electrolytic action. Once the corrosion is cleaned up prime with a quality epoxy primer immediately. No need to acid etch and alodine after bead blasting. Sanding as a removal method, is in my opinion a complete waste of time, because the corrosion is not completely removed and is still prevalent in pitted
areas, and you would completely sand through the .032 skin trying to remove it all. Shoot the seams back together wet with a quality sealant to prevent any more moisture to wick into the seams.

[J. Morgan]

While it is pictures that I am looking at, and I might not be seeing everything, if the trailer were mine I would be inclined to;

A. Mechanically remove the lose and scaly stuff.

B. Stop the ingress of water and moisture.

And that is about it.

Aluminum oxide, can be looked at as a protective barrier.


Talis gentium ceciderunt.

[mimiandrews]

What Aerowood said.

[J. Morgan]

So the good advise is to remove all of the external aluminum walls and bead blast everything?

Is it really worth all that to have a pretty trailer under the inner skins?

If that corrosion is not visible from the outside or does not affect structure in a significant way I think that is awful advise.

Descale, stop the water intrusion that is feeding the corrosion and MOVE FORWARD with the project.

Aluminum oxide does not progress like rust, if you stop the constantly wet environment, the corrosion will stop.

In the end no one is going to give a shot about how pretty the trailer is under the inner skins and insulation.

Sorry to disagree, but I do.




Talis gentium ceciderunt.

[Protagonist]

Originally Posted by J. Morgan

So the good advise is to remove all of the external aluminum walls and bead blast everything?

If that corrosion is not visible from the outside or does not affect structure in a significant way I think that is awful advise.

Descale, stop the water intrusion that is feeding the corrosion and MOVE FORWARD with the project.

Aluminum oxide does not progress like rust, if you stop the constantly wet environment, the corrosion will stop.

Sorry to disagree, but I do.

I'm with you, actually. That's why I recommended WD40 and a pot scrubber to remove the oxidation. So much less invasive than bead-blasting.

Not to mention that if abrasive blasting was required, using a soft abrasive media like baking soda (soda-blasting) is so much better for "delicate" surfaces like thin sheet metal.

Wry side note— ever notice how people always say "not to mention" right before they do mention?

[J. Morgan]

I looked and Aerowood is an aircraft mechanic.

I would likely want all of that done on a plane I was flying in, but a might bit of overkill on a travel trailer IMHO...

We have to find a balance between perfection and practicality.

The remedy that was offered will more than double the scope of a trailer rebuild.


Talis gentium ceciderunt.

[Aerowood]

Originally Posted by beckettnole

I was warned also that it may be impossible to stop long term so any advice on anything additional that will mitigate/slow/stop it would be greatly appreciated


Warm Regards

Ryan

I was just answering this question. As always there are always people that want to do the fast, easy and cheap way to do things.

[J. Morgan]

Sometimes fast, easy, and cheap makes the most sense.

A lot of folks don't buy a travel trailer with the intent of working on it for six years before being able to go camping.



Talis gentium ceciderunt.

[twolanehwy]

If you have a little air grinder you can hit those spots down until pitting is gone.
aerowood has the right idea because even if you stop the leaks it will sweat under there and will continue until it comes through on the outside.
So if not bead blasting small die grinder with 36 grit will make fast work of it, seal after with undercoat spray and make sure leak is stopped.
If you are not keeping the trailer then don't worry about it.

[truckasaurus]

In my opinion (also a licensed aviation tech not that long ago) the PO would be wise to spend the extra few hundred bucks on new sheet metal as they're doing a full project already. No remedy for repairing badly corroded sheet is going to work medium term and maybe not a big deal to some but that is structural skin that's failing. Amateur blasting even with soda is going to warp the skin and scrubbing is going to be a PITA and just delay the inevitable. It just seems a bad way to save $200 on a big project but it's not my trailer so it's just my opinion