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Eagle & Bear · 12-05-2016, 03:50 PM

We have been renovating and polished a 29' 1976 Ambassador for 10 years.* My polish job was almost finished but there was some heavy oxidation on the caps that I planned to remove this winter ('16). We decided to take our AS to the Yukon this last summer.* On our way to Dawson*we took a*side trip*to Tombstone National Park.**

The 20 mile drive was on a dirt road and the dust coated the van* and trailer.**Did not worry about it because dust*has never been a problem in the past.* The day after we arrived at camp*it rained.* The rain washed some of the dust (40%?) and left the rest in streaks.* What was left was a very fine grain brown sand*(maybe 400 - 600 grit?) that*did not washed off in the rain.*

The road has a lot of traffic and is well maintained.* I doubt if the*road bed is made of native material and*it doesn't look like they oiled the road.*

The area we camped in had no water we could use to wash the dust off.**It was*a week before we could get to*the first*car wash in Dawson.**I used three different high pressure*washers and soap but*they did not remove any of the residue*from the trailer. It was easy to wash it off our tow vehicle and other painted surfaces.* I was trying to avoid scratching the surface but*I did use a sponge and soap on the residue.* I was able to wash off the brown outer layer but there is a white material that seems to be bonded to the aluminum underneath the sand.

Given that water seems to have played a role, I am guessing that it is NaCl or calcium chloride that is causing the surface to turn white in areas.* In addition,*I do not know why the fine brown sand particles seem to be bonded to the white patches.* When I remove the fine sand particles the*aluminum surface under the sand seems fairly smooth but there are small (1mm)shallow pits <1mm deep.* I suspect if I leave the material on the aluminum surface it the pits may be deeper fairly soon.

The only thing that seems to remove the fine sand particles is CLR (bath foam) and a soft brush.* I have cleaned off about 1/4 of the skin surface and will work at it every day until I have removed all of the sand.* The CLR may have nothing to do with the sand removal but the soft brush did help. My plan is to use Nuvite 9 polish to buff the white stuff off - if it is cooperative.

This is going to be a lot of work and I do not want to cause more damage than I already have. If anyone has experience with this kind of problem (or want to throw out a theory) and found a solution would you please let me know.* Lives may be at stake. No clue why the * are popping up in the text.

perryg114 · 12-05-2016, 04:24 PM

Use a fine grit emery paper to cut through the corrosion/funk then repolish. Start with 400, then 1000 then polish. Experiment on a small are to get some idea where this is going. Wax will protect the surface from corrosion for a while. Steel wool might be a last resort to get the sand off then try emery paper and polish to get the finish back. Removing the sand and corrosion is something you better do soon. You can always remove light scratches but large corrosion pits are always going to be there. You could try vinegar over a small area and see if that works. CLR has some pretty harsh chemicals and may discolor the metal.

Perry

Wayne&Sam · 12-05-2016, 05:11 PM

[QUOTE=Eagle & Bear;1883933 No clue why the * are popping up in the text.[/QUOTE]

I was going to ask. They completely distracted me so I can't help you at all. Of course I wouldn't be of any help even if they weren't there***

tjdonahoe · 12-05-2016, 08:07 PM

Calcium chloride is used for dust suppression, also sprayed on icy roads ,to melt the ice ,above 21 degrees,...is highly corrosive and will pit stainless..

Eagle & Bear · 12-06-2016, 12:32 AM

Did more research. So far it looks like I should use a detergent with a low pH (<4) to stop the corrosion and possibly make it easier to remove the sand. So far magic incantations and car washing liquids have not helped. Any other ideas would be welcome before I totally destroy the surface aluminum with 400 to 800 grit aluminum oxide wet/dry paper.

mimiandrews · 12-06-2016, 05:46 AM

Steel wool might be a last resort

No! Never use steel wool on aluminum. It will leave micro bits of steel imbedded in the soft aluminum and set up galvanic corrosion at each bit.

ALANSD · 12-06-2016, 05:53 AM

as for the steel wool have you ever seen Gord's polish? They recommend it. The emery paper will not ruin the surface if it is done carefully and in lighter grades coarse to fine. I have used it and black rouge to get corrosion off my 66, although I still have more to do it worked well. Then you polish with your favorite substance and make the lines go away that the grit leaves.

mimiandrews · 12-06-2016, 05:59 AM

In aircraft sheet metal work, corrosion is feared like cancer. I was taught that steel wool sets up corrosive conditions that will last well into the future.

Of course, aircraft structure has to be light, so it's usually not much stronger than it has to be. And failure can be far more life-threatening than loss of the shine.

Just so you know where I'm coming from....

ALANSD · 12-06-2016, 06:24 AM

I am only stating that the Gord's polish guy is big on 000 steel wool for the first pass with his polish. Honestly the stuff did not do such a great job for me. At the level of shine I prefer, which is shiny but no mirror, I prefer a cyclo with ToolBox polish. I store my trailer outside and can't maintain a show car finish. However I do want it shiny and clean.

I got onto the Gord's from seeing a guys trailer at two different times, before and after. It did look really good and he said it was relatively easy. Being he was an older guy than me, who was not in the best shape, I figured on trying it. After all I have used rouge bars, and everything else out there in my 4 Airstream ownership. Well the stuff became handy for the chrome on my old cars, but not much more. I have a full bottle sitting in my detail cabinet.
The best method I have seen is the wheel and rouge bar method of polishing, as demo'd by "Dr Airstream " who was an attendee at our rally here more than a few times.
cheers!

dwightdi · 12-06-2016, 08:31 AM

I am not certain what they put on the road that far north but it might be pretty aggressive to melt ice in those kinds of territories. We can not be sure what the white corrosion products would result. I presume it might be similar to the white deposits found in the forfill corrosion aluminum wheels and later model Airstreams experience. Likely to be predominantly be AlO. That is a pretty inert compound. Mechanical means (brushes)are likely to be the best way of removing it. Detergents would help. There might be some AlCl2, which is also pretty inert. You would need to use a chemical product that has a metal element with a higher activity that aluminum to dissolve it.

Eagle & Bear · 12-06-2016, 11:31 AM

From what I can gather this road is used in the winter - it goes to the Artic Ocean. Looks like they put calcium chloride on the surface to limit the ice buildup. There may be sodium chloride applications as well but either way it is not good for a polished aluminum surface.

Some of the recommendations I have read about say to use a low pH detergent to wash the surface. Will get something today but I may have to settle for a dish soap and white vinegar mixture. I have washed the trailer 5-6 times but will do it again just to neutralize the effects of what is causing the oxidation and pits.

Brillo pads come in different grades so I will pick up some of them and see if I can find an abrasive material (nylon like) on a stem so that I can remove some of the oxidation and mystery material with a drill.

After all of that I will use Nuvite 9 or 7 to get the scratches out and then go to S for the final polish. I am using a Porter Cable variable speed, oscillating polisher throughout the process. I hope to be done in 2014.

NevadaGeo · 12-06-2016, 11:37 AM

Do you suppose it might be an asphalt oil emulsion, that might could come off with a solvent.

lsbrodsky · 12-06-2016, 11:40 AM

I must first confess to no experience with your issue, but as a chemist by degree, not career, I wonder why you would want to use an acid to clean aluminum. Flies in the face of do not etch, do no harm. I would think you would want some sort of chelating cleaner, neutral or slightly basic, but mostly mechanical/abrasive. Have you tried a paste of baking soda? Maybe Barkeeper's Friend?

Larry

Boxite · 12-06-2016, 12:20 PM

Many detergents/soaps/etc will tarnish/anodize bare aluminum. One product with which I am familiar ..which even CLAIMS TO BE SAFE on aluminum aircraft...a "Simple Green for Aircraft" product... actually imparted an anodized, whitish surface on my polished aluminum classic aircraft.

Fortunately, I only tested it on a small spot.

It may be necessary to repolish your airstream. Then clearcoat it.

Unless clearcoated, I would advise against detergents on bare aluminum for the reason mentioned. (I wash my non-clearcoated aluminum airplane using only a few cups of WD40 forcefully mixed into a 5-gal bucket of water. I then rinse with water and dry with old towels.)

JCWDCW · 12-06-2016, 12:33 PM

You don't want to use (strong) caustic on aluminum...it dissolves it; although baking soda probably is too mild to do damage but is likely the wrong side of the acid/base question. I believe you need the acid pH soap which will neutralize any base salts that may still be active, and pH 4 is not very acidic at any rate. I think others have covered it pretty well. You have been affected by calcium (and no doubt, some sodium salts).
If you can't get an acid pH soap you can use some vinegar added to dish detergent or hair shampoo. No point in using laundry Detergent as it will immediately neutralize the acetic acid in vinegar. You might even just rinse the skin with a vinegar solution. one cup to a gallon or even a half gallon is probably OK. Definitely try a patch.
Salted roads up here in the chilly north are something I avoid like the plague. Any bare aluminum gets pitted! Got caught in it once ...never again.
I don't know very much about polishing so others are better at answering but I'm guessing you need to re-polish, as the exposed surface has now been chemically etched.
JCW

NavyCorpsman · 12-06-2016, 01:18 PM

I agree with Boxite. WD40 will not harm the metal and will put most surface contaminants into suspension. It's not a spray and wipe deal, need to rub until the Jeanie appears......use your wishes carefully. I am in the process of polishing mine and have learned a couple of things. When attacking gunk and scratches, start with superfine abrasives and go to a coarser grade as required. When you are satisfied, polish with grey compound and finish with Mothers mag and aluminum polish with a black finishing pad. Seal with your favorite polish and buff.
For the really tough areas, I have used Zep purple cleaner (Butoxyethanol and Sodium Hydroxide). Mix with water to a 25% solution and use a soft brush to the area. It will leave a matte / satin finish and will streak if you don't use copious rinse water. It does create a nice clean surface for polishing. Let us know what worked when you're done.

Eagle & Bear · 12-06-2016, 04:53 PM

First I want to know the story behind BOXITE's avatar and what was the outcome?

Thanks to everyone who has commented. When I was referring to the Brillo pad I was thinking of the nylon or synthetic scrubbers - not metallic pads. I did not find any at ACE Hardware but will look elsewhere tomorrow. I did find an auto paint shop that carries a good selection of wet/dry sand paper 600 grit to 1400 grit.

At this point I have lots of small pits on the surface. The pits are 1-2 mm in diameter, spaced at .5mm-.7mm apart and, at this time, they are very shallow. I wanted to do a mild acid wash to stop the progression of the pitting. I used 3 gallons of warm tap water, 1/4 bottle of dish soap and 1/2 gallon of 10% white vinegar.

I did not want to take the time to find strips to measure pH so I lathered the skin in the solution for 1/2 hour with a micro fiber mop on the curb and street sides. Did a lazy rinse hoping to leave a slight residue on the skin until the morning. Nothing scientific or rational about that move; I just want to stop the pitting. Have no idea what the pH is but it is done. Most of the sand has washed off and I do not see any additional oxidation.

What is left is the same superficial oxidized streaks that run down the sides of the AS. It may be some kind of etching but, regardless, I do not want the original calcium based material to erode or pit the skin anymore than it has already. Nonetheless, I will have to buff/polish the entire trailer.

I have terry cloth, flannel and wool bonnets for my polisher. The Nuvite 9 should be here tomorrow. I will try some on an area to see what happens. If it leaves an acceptable surface that I can use S on I am good with that. If not I will switch to Nuvite 7 and see what I get. If anything is left of my shell I will post photos. If not I hear there are some new products that will coat the skin with a durable white material which will not chalk. JK

perryg114 · 12-06-2016, 05:03 PM

My Bad.

I was thinking of Scotch Bright which is even more abrasive but not corrosive.

Perry

Quote:

Originally Posted by mimiandrews

Steel wool might be a last resort

No! Never use steel wool on aluminum. It will leave micro bits of steel imbedded in the soft aluminum and set up galvanic corrosion at each bit.

Eagle & Bear · 12-06-2016, 05:33 PM

This is one of the articles/papers that I have been using to determine how to minimize the damage to the skin of my Airstream.

http://www.pfonline.com/articles/alu...roubleshooting

ALANSD · 12-07-2016, 09:44 AM

Many people use ALMABRITE (spelling?) mild acid to clean their aluminum before polishing. I have used it effectively in the past on several trailers...I dont leave it on very long. Wet the surface before and after.
If it leaves white streaks or dulling, the light polish I do with ToolBox polish brings the shine right back.