Exterior Corrosion Repair

[PaulAir]

I found a bunch of threads talking about the corrosion types and preventive measures, but nothing in detail about how to fix them.
So, I'll start a new thread in hopes of getting advise, thread links and presenting some concise information on how fix these areas as I have a few.
I'll start with pictures. I progressed through the following:
1) deoxidizer
2) razor blade some of the thicker stuff off
3) 320 grit sand paper
4) Brass wire brush
5) polish

I'd like ideas on doing things differently as I'm not finished yet. This is also the first spot I'm attacking as the new owner.

How to rectify the pitting?
How to restore a "brushed finish"?
What are the best clear coat products that will last?
Thanks,
Paul...

[Wingeezer]

Wow, that is a lot of corrosion - I too have a 2005, and have a couple of very minor (so far!) spots of skin corrosion. Most of mine is on the aluminum frames of the battery bx doors and on the grab handle to the right of the entrance door.

I haven't gotten around to it yet, but my feeling is that I wouldn't likely be able to repair the corrosion of the battery box frames and door handle so as to make my repair invisible, so that instead of even trying, I would sand the corrosion smooth and then very carefully paint with something like tremclad alum paint.

I think I could probably make it look better that way if done carefully. I wonder if such a solution might work in your case? Maybe wound't be so good on teh trailer skin, but something to think about.

Did the previous owner have the trailer on or near the coast?


Brian




In a similar vein, I once managed to poke a neat 3/4" home into the side of a fibreglass trailer - again, I figured that an invisible repair would be next to impossible, so instead I filled the hole with epoxy, then put a small Canadian flag over it! It was in a location in which it did not at all look out of place! Only I knew the dirty secret!


I'll be interested to see how you lake out.

[87MH]

Originally Posted by PaulAir

...I'd like ideas on doing things differently as I'm not finished yet. This is also the first spot I'm attacking as the new owner.

How to rectify the pitting?
How to restore a "brushed finish"?
What are the best clear coat products that will last?...

No "fix" to it that I know of other than to buff it out.

If you have multiple spots that are similar I might start with an off the shelf clear laquer or enamal that would be compatible...try it on a hidden area first to try it out.

As to how to put a stop to it - I have often thought that an electrical leak may be at fault - especially since the spots in your pics seem to be symetrical around the light fixture.

I have plans to install a couple of pounds of very active zinc as a sacrificial anode (like an anode designed to be installed on a big outboard motor) on the '78. I will probably put the anode(s) on the frame towards the rear.

It would not take much time to see the detriment of the sacrificial anode if it is really working - the amount of aluminum oxidation on your unit indicates that something bad is going on.

Is there anything else indicating that you may have a voltage leak to ground or any other stray currents eating at the battery, skin, or charging system?

What about the famous "rear end leak" any chance of moisture staying where it should not and creating a "lydon jar" (simple battery) effect using the aluminum skin as an anode?

[truckasaurus]

Paul, I don't have any great solutions for you but if you have pitting corrosion you're in a bind. Ideally you'll want to remove the pitting otherwise you'll just be partially treating the problem. A die grinder with a Scotchbrite disc or Cratex wheel is great for this. If you can get it all out then sanding followed by Scotchbrite leaves a brushed'ish finish. Looking at your pictures I seriously doubt that you'll get the the pitting out, it's horribly deep. You might consider a patch (flush or surface) or considering your trailer is quite new a whole skin, just thinking out loud.

[PaulAir]

Thanks for the suggestions... I was hoping for something other than buff and coat, but one can hope. Thanks for the scotchbrite suggestion for restoring the brushed look.

Originally Posted by 87MH

As to how to put a stop to it - I have often thought that an electrical leak may be at fault - especially since the spots in your pics seem to be symetrical around the light fixture.

Dennis, I'll ohm out 12V and trailer lights circuit the trailer and see what I find.

Originally Posted by Wingeezer

I would sand the corrosion smooth and then very carefully paint with something like tremclad alum paint.

Did the previous owner have the trailer on or near the coast?

Brian,
Thanks for the paint idea. I'll have to see if it yeilds a close match with a flat. From what I've been reading, it sounds like these late models will eventually become argosys.

The trailer came from close to the gulf coast, so I expected it wasn't kept with a protectant.
I want to get these spots tackled and hopefully keep the other minor spots in check with T9 and WashWax treatments.

I'll post pictures after the next phase... need to get some things.
Paul...

[flyingfinn]

It's the same as fixing airplane corrosion. Make sure you do not use a steel wire brush on aluminum

[Lance M]

Hey Paul,
Here is a good lesson on corrosion removal. See paragraph 6-136. It is basically remove, treat and continue to operate. You are on the right track, for sure. A good corrosion preventative compound (CPC) like corrosion X, should be used on areas with corrosion until repairs can be made. Good luck!

[ROBERT CROSS]

I know you probably haven't read the entire Thread,...http://www.airforums.com/forums/f142...s-31743-5.html reads like "War & Peace, but on posts #489 & #493 I addressed the Battery doors & entrance door hinges.

The Filiform, in your pictures is a very different concern. NO wire brush or 320 sand paper will do any good, you won't polish it out and be able to match the clearcoat.

What I have done.....scrape out the corrosion, WD40 helps a lot. On a large area, like your marker lights, tape around the area, sand with 600 or above wet paper...plenty of WD40. Clean with mineral spirits, and cover with auto touch-up clear coat. On those larger areas a spray CC might work better, hard to blend though.
Believe me I've tried...aluminum and stainless steel paint have worked on small areas....around bezels and such, hard to pick out beyond 15ft, but still there.
Iv'e had good luck with the periodic application of the WD40 to keep it from spreading. Bioshield and CorrosionX, not so much.

I've come to the conclusion, after all these years....ain't no way to to make it disappear, just look a little better.

Good luck in your Quest....keep us posted.

Time devours all.....

[PaulAir]

Great Info, Thanks!

Originally Posted by flyingfinn

Make sure you do not use a steel wire brush on aluminum

From TOP's post:
(b) Stainless steel brush may be used as long as the bristles do not exceed 0.010 inch in diameter.
(c) Steel wool, emery cloth, steel wire brushes (except stainless steel brush) copper alloy brushes, rotary wire brushes (oops, but the brass brush did work, I'll have to find the ss brush)

Linking Robert's great work here:
http://www.airforums.com/forums/f142...tml#post606944
http://www.airforums.com/forums/f142...tml#post607273
Seems the 1500grit paper gives it that brushed/matt look.

I've got the same issues on the door hinges, they're on the list...

[Silver Otter]

We have a bit of this around the battery doors. I appreciate all the advice, and will try to polish it out. Keep up the good help. Thanks.

[PaulAir]

Wow, the pits are very deep. Grabbed supplies and this is what I've done.
1) small sand blaster (harbor freight)- I thought this would be great, but quickly realized that it will remove material regardless including at the bottom of the pits, which I DON'T want to go deeper... abandoned that for this task, but may use it elsewhere...
2) Nylon bristle wheels- 200 grit paper wasn't even close to get here. I went with 120 grit disc and moved to 80 grit disc followed by 120 again to get here.

Next steps...
I have a Scotch brite wheel that I will use before going to 200 wet sand and followed by 400 and 1000 grit. After that, polish, 1000 grit or higher for brushed look, deoxidize, degrease, clear coat, and wax... then on to the next one.

I don't think I want to take down more material and just round the corners of the pits to seal them up. It won't look too bad when it's done.

[Mike Leary]

I might be on the wrong thread, but after a lifetime in waterworks, I know something about the cause of these problems :

Dissimilar Metal Corrosion

[05ModPod]

Perfect timing for this thread - I too have a 2005 and it is having corrosion issues. In particular the door hinges, handle and rear lights, and the wheels. I have a few spots on the trailer skin - one near a rear marker light and another hmm can't remember.

The hinges and handles and rear lights basically I will remove and strip/polish and re-clearcoat.

The filiform on the skin - well I will try and clean it as best as possible - not bring out the big take down of the skin method to leave me with altered aluminum.

The best practise is to remove as much of the corrosion as possible with as little invasiveness as possible and then prevent it from spreading.

I have never done this before - so not sure what approach - so all the above ideas a great food for thought.

The only bit of advice I might be able to offer is when you come to spray your clear coat - and masking the area. A long time ago I learned to take paper and curve the ends - like you would roll a newspaper - rather than masking tape with straight edges.

This method allows the spray paint to feather to the existing paint and blend without any distinct lines. I was amazed how that tip worked when I was doing body work on several of our cars over the years.

Good luck with the up-keep of corrosion - real pain - but try to enjoy the camping aspect more that fretting over how she may look with a few spots here and there - but don't let it go too long.

Corrosion for us Cannuck is inevitable - especially when we travel through the winter, she sits in the winter and we head south to where the ocean is - it is a wonder my baby is not all wrinkled up with filliform to the hilt by now.

[floridalarry]

Yep, I have them too. While at the Sarasota Rally, I showed them to an Airstream tech and he said to catch them early, use my fingernail to fleck away the white residue and coat with clear fingernail polish. Airstream sells a tube of clearcoat touch-up paint, but fingernail polish is a whole lot cheaper and works just fine. Any time the clearcoat is broken, water gets underneath the clearcoat and an oxidation spot begins to grow. I have them along my rub rail, seams and most places where the clearcoat has been broken. You will never get to the source of many of the breaks because they are under an item that has been riveted onto the surface. To pull my rub rail would be a very expensive job. The aluminum panels come to the factory already clearcoated. During assembly, when the surface of the panel(s) is drilled or the edge is scuffed, the results are oxidation spots. I have tried using a knife, sandpaper and a Drummel tool wirebrush, but the results don't look good. Catch them early and often, and keep 'em coated.

[ROBERT CROSS]

aluMATTER*|*Aluminium*|*Forms of Corrosion*|*Forms of Corrosion: Introduction
aluMATTER*|*Aluminium*|*Forms of Corrosion*|*Galvanic Corrosion

I don't believe the the filiform corrosion is caused by galvanic action, I believe it only turns up on a coated surface. If the coating is damaged during assembly, usually on a panel edge or rivet hole, there is a good chance it will start.

I do know it's very difficult to make disappear completely, Good luck to all who are trying.

On the upside...the first few years we had our trailer it seemed to be popping up everywhere, not really severe in our case, but a real PITA.

I did what I could at the time, and it HAS slowed drastically the last few years.

[ROBERT CROSS]

Maybe there is hope for a more corrosion resistant alloy.....
Wonder how thin they can make it?


Mikhail Voevodin, General Director, VSMPO-AVISMA Corporation said: "I am confident that cooperation between VSMPO-AVISMA and Alcoa will result in significant accomplishments, yielding new solutions in the commercial transportation industry."

One result of the MoU may be the development of wide (up to 700 mm or 27.5 inches) and long (up to 26 meters or 85 feet) extrusions made of advanced aluminum alloys designed for passenger and freight cars, including next- generation high-speed rail for the Russian market. These aluminium products will increase the energy efficiency and reduce the carbon footprint of rail cars through light-weighting and the infinite recyclability of aluminum.

Alcoa and VSMPO-AVISMA will form working teams to coordinate the execution of projects resulting from this MoU. The MoU does not signal the establishment of a joint venture, partnership or any other formal business entity between the parties.

[captmatt]

Originally Posted by 87MH

No "fix" to it that I know of other than to buff it out.



I have plans to install a couple of pounds of very active zinc as a sacrificial anode (like an anode designed to be installed on a big outboard motor) on the '78. I will probably put the anode(s) on the frame towards the rear.

It would not take much time to see the detriment of the sacrificial anode if it is really working - the amount of aluminum oxidation on your unit indicates that something bad is going on.

Is there anything else indicating that you may have a voltage leak to ground or any other stray currents eating at the battery, skin, or charging system?

What about the famous "rear end leak" any chance of moisture staying where it should not and creating a "lydon jar" (simple battery) effect using the aluminum skin as an anode?

Have you tried this yet? Sounds like an awesome preventative thing to do! I run commercial aluminum boats in salt water and the anodes help a great deal. I'm tempted to slap a small one on the steel frame and one on the outer skin just to do what they are named for... be sacrificial!

[ROBERT CROSS]

Originally Posted by captmatt

Have you tried this yet? Sounds like an awesome preventative thing to do! I run commercial aluminum boats in salt water and the anodes help a great deal. I'm tempted to slap a small one on the steel frame and one on the outer skin just to do what they are named for... be sacrificial!

I do believe this will only work if you plan to float or bury your Airstream.

Hard to camp then!!!

Galvanic anode - Wikipedia, the free encyclopedia

[flyingfinn]

I had asked how to remove water spots off the skin of a 2008 Safari. It had sat by sprinklers for a couple of years in Nevada heat. I tried various compounds and rubbing but nothing worked. Finally I used distilled white vinegar. With modest rubbing, all of the spots came off. Thanks for the hint.

[mrgreen]

They do this in tidal locks, i've seen Mike Rowe down there replacing plates, but i'm geussing it aint gonna work on an Airstream as i'm geussing it all is localised, I must say i am suprised to find 6 year old trailers with this problem i would have thought sfter so long in the business Airtream would have found a fix of sorts!, thank god for airstream their trailers look cool eh!!!

Originally Posted by captmatt

Have you tried this yet? Sounds like an awesome preventative thing to do! I run commercial aluminum boats in salt water and the anodes help a great deal. I'm tempted to slap a small one on the steel frame and one on the outer skin just to do what they are named for... be sacrificial!