Question about white aluminum oxide deposits

[williamhenshall]

Anyone got any solid advice about what to do with the white aluminum oxide (I think that's what it is) that is on the inside of the outer skin in several places? Is there a product recommended to clean up this? I dont want it to spread...

I'll check back later today

Will

[niftypkg]

William. I removed some of these deposits using a bathroom tile mineral deposit remover and scrubing with steel wool. The one I used was 'Eliminate' from HD. However they were not as pronounced as shown in your pix. Try scraping the heavier stuff off and then applying the cleaner. Let me know.

[BobbyW]

Visit your local motorcycle store. Aluminum oxidation is a motorcycles worst enemy. It can really ruin the looks of cast aluminum heads and cases. The show bike guys know all the tricks. They have all kinds of products to remove the oxidation and they are safe for aluminum. I would not use any of these on the outside, but the inside would be fine.

-BobbyWright

[83Excella]

Looks like corrosion to me and you will need to eliminate it or it will return, getting in the corners will be tough but try covering it with some POR-15 silver after you clean it up. You can use 'red' scotchbrite if you cant sand blast it using glass beads not sand.

John

[Road Ruler]

Will

We had a Coleman Rio Grande pop up for years. In the late fall coming up from Virgina Beach we got caught in a few snow storms coming through Buffalo and Pennsalvania with lots of salt on the roads. A couple of years later I noticed holes and white blistering coming through the "aluminum" door. We kept the trailer washed and polished so I was surprised to see the problem. I completely disassembled the door and found the 1/4 inch hardboard inside soaked with moisture. The aluminum panel on the insde looked just like your photo. I replaced the hard board with new that I painted with marine paint and brushed on a coat of "Rust Check" rust prevention solution on the damaged aluminum.
This seemed to stop the corrosion problem.

Note that rust check in a sealed envierment will not dry out and will repel oxygen and moisture which is the enemy along with salt.

I have been using the "Rust Check" and "Crown" products on all of out vehicles for the last 18 years. I buy the liquid and spray it on myself with gun and compressor. It works!

[53flyingcloud]

"Waste not, want not"
deposit in your local Airstream Bank.

[otha1]

Another marine product might work well here. It's called Ospho, and is merely a mild solution of phosphoric acid. Available at marine, and some hardware stores. At hardware stores, look in the paint dept. Ospho is often used as a rust fixative before painting. Once you remove that corrosion, you need to determine the source as stated above, to make sure its stopped or it will eventually eat thru the skin. Also, as stated above, its a good idea to coat the area with one of the products others have mentioned.

[Auretrvr]

We have removed all of the padded storage doors that are along the twins in our '83 310 motorhome (as well as the ones under the sofa). I am going to recover them. When I removed the screws and vinyl coated aluminum that is attahced to the padding board. I found a white powder that rubs off with my finger only on the pieces adjacent to the freshwater tank. There is no evidence of leaks in the area. These had been covered over once, ten years ago, and they used regular staples to afix the fabric to the boards on all of the doors. I am guessing that the tank has some condensation at times. Is it possible that the moisture, combined with the staples caused the corrosion? I noticed that the sofa was stapled with copper staples to avoid rust and had planned to use those on the doors. Now I wonder if copper reacts too. It will never show, but if this is a little thing that could become a big thing, I want to deal with it. On the other hand, it has been there since the last renovation and I'd never have known had I not looked. What do you think?

(No signs of such powder anywhere else. Whew!!)

[Aerowood]

Yep its corrosion alright. The only way to clean this up properly is to remove the panel from the trailer. Glass bead blast as already stated then clean with Alumiprep, (acid etch), alodine, then prime. This will need to be done to all the mating parts also. It would probably be best to just replace the panels and attaching channel. Corrosion like rust is a cancer to alumnium and unless its completly removed and the area nuturalized, no amount of scrubbing cleaning and good intensions will stop the process unless it is properly delt with. I've got this on my trailer and the skin and attach channel is going to be replaced.

Kip

[vhord]

Has anyone tried Duro Aluminum Jelly
Loctite Consumer Retail Products | Home Repairs & Home Improvement Projects

Their web site states that it

Restores and brightens dull, oxidized aluminum in minutes
Quickly and easily removes layers of "white rust," dirt and grime -- simply brush on and rinse off

I have a few small areas inside the outer skin. Left untreated but dry will it eventually corrode through to the outside? Over what approx. length of time?

My thoughts are that if it did eventually shows its face from the outside couldn't I just as easy replace a section of outer skin then as now.

[olddog299]

Originally Posted by Auretrvr

{snip} Is it possible that the moisture, combined with the staples caused the corrosion?

Yep.

Originally Posted by Auretrvr

I noticed that the sofa was stapled with copper staples to avoid rust and had planned to use those on the doors. Now I wonder if copper reacts too.

Yes. In fact, two dissimilar metals and a tiny electric current in the presence of a eutectic (salt) = storage battery and you have corrosion. Hence the use of a sacrificial anode in the hot water tank...

[Aerowood]

Same reply as in the post #9 above. It all depends on how deep your current corrosion is. It doesn't take to long to remove .032 of skin.

[CTDesign]

Ok this will open up a huge can of worms so I’m already braced for it.
I’m a mechanical engineer who just acquired a 1973 25’ land yacht in the process if my tear down for a rebuild.

Aluminum oxide INSIDE your airstream is your FRIEND. Outside, it’s nasty and ugly. We remove it to make it the beautiful gleaming silver bullet we like to admire as it glides down the highway. Inside, we want to let it remain in order to protect the aluminum like the green layer of copper oxide that protects the statue of liberty’s coppery shell.

Your steel frame is another subject and it does need to be cleaned and protected from oxidation. This post is strictly applied to aluminum.

Many aluminum material forums will have a statement something like this… “ Aluminum doesn’t contain iron or steel so it doesn’t rust – but it is prone to corrosion when exposed to weathering and atmospheric oxygen. The process of aluminum corrosion is known as oxidation. The resulting aluminum oxide is a thin, hard layer that actually protects the metal from further corrosion.
Aluminum oxide appears as a powdery white or dull gray coating. As oxidation occurs, it hardens and creates a protective layer over the newly exposed areas of corroded aluminum. The aluminum corrosion process is actually halted by oxidation – the metal won’t continue to deteriorate unless the aluminum oxide is removed”
This original article can be found by googling “allmetalsfab does aluminum rust”

The primary reason you’re seeing this oxidation is because water is making contact with that interior surface of the aluminum, which was not plasticoated from the factory like the exterior. There are 2 primary sources for this water. Obvious #1 is water may have leaked from a seam or joint from the exterior. Not so obvious #2 is condensation is occurring due to the humidity inside the trailer making contact with the cold metal shell when it’s warm inside the trailer and cold outside.

When you breath and sweat, you’re introducing moisture into the air. You’d be surprised how much the human body expels moisture into a building. We have to account for this when designing HVAC systems. Showering, cooking, hot dish water, etc… also obviously contribute.

If you google “moisture control for home construction”, you’ll find a crazy list of articles and YouTube videos discussing this topic. My favorite is Matt Risinger’s “The Build Show” series. He does a fantastic job of explaining this. The trick is to let the building breath, allowing moisture to escape and dry out the shell. Hard to do in these beautifully crafted aluminum airstream containers.

Then we get into insulation and how we close the cavity with new interior paneling after we’ve re-wired a rebuild, etc…. It’s a long discussion. One I’m willing to post more about if you’re interested (and if i don’t get my head handed to me too harshly )