Cloudy Blotchy Blues

[dbj216]

I have been slowly progressing on polishing our Airstream. The resultant aluminum surface has random cloudy areas. I have attached a couple of pictures, but it is difficult to see. It is most visible in the daylight shade. The aluminum surface has good reflectivity and is quite smooth, like a clean mirror.

I'm thinking it is residual polishing "mud" that is somehow embedded in the pours of the aluminum. I clean with kerosene, wipe dry and repeat until no black on the terry cloth, and then corn starch and dry wipe until no black. I have tried lacquer thinner to no avail. I use Nuvite S for my final polish.

I'll bet other experienced polishers have delt with this problem. Can someone offer some advice?

David

[Melody Ranch]

Looks like you did not compound enough...with a heavy enough polish. I see some scratches in the second picture which should polish out.....same with the spot in the first photo. I assume you did strip it all completely befor the initial polish.

[InsideOut]

How are you doing your compounding? Does the area "change" if you compound it more? If the area seems to "match" at first then the cloudy areas show up a day or two later (or only in the "right" light) it could be that you polished through the Alclad. The different aluminum alloy base could be showing through.

It's pretty hard to burn through the Alclad - but it is possible if you have worked an area a lot trying to get out a scratch or something, then kept going trying to get it to shine & blend in.

Does it look like it is a darker color metal? If so, it's because the alloy is different - it shines, but it will oxidize differently than where the Alclad is still intact once the moisture in the air hits it. Also, the more you try to get rid of the cloud, the bigger it gets if this is the case. Could you possibly have over worked those areas and gone through the Alclad? Unfortunately, no amount of "cleaning" will get rid of this.

Alclad is a "whiter" colored aluminum alloy that is a softer, thin coat over a base sheet of aluminum with a stronger alloy make-up. The purer aluminum top coat can be burned through a couple of different ways:

1) too coarse of a compound is used
2) sandpaper is used
3) the area is overworked from too much pressure on the compounder
4) the area is overheated when compounding

Not certain this is the case, but it could be the cause - the first picture looks more like it to me than the second because of the shape of the splotch. It looks like the same concentrated area was gone over & over back and forth. The second picture is harder to see - it doesn't look as concentrated, it looks like it's a bigger area but less distinct of an outline - like it isn't as far gone, there is still a very thin coat of Alclad there.

It's so hard to tell the difference in a photo - but the fact you say it rags comes clean of polish & and the shape of the cloud in the first is what makes me suggest this might be the cause. Sorry, I hope I'm wrong - but it has happened to the best of us!

Shari

[dbj216]

Thank you folks for your thoughtful replys. I compounded with F7 and then C with a 8" wool bonnet and a 1/2 drill at at 700 rpm. I pushed pretty hard to get through the oxidation. I don't know how hot the aluminum got but I don't think much over 100. I think using the buffing method with the rouge bar to charge the wheel is riskier as the surface is being worked in a much smaller, more intense area that with a large bonnet. Polishing is smearing the surface metal "peaks" into the "valleys" making it smooth and shinny. I tried to compound in random directions to help move the swirls around. I would say I have always had the blochey shadows. Maybe it is a result of the inconsistant compounding. Or maybe it is still "mud" in the valleys that I can't get out for some reason.

I wonder if each of us of 25 year old Airstream aluminum with faded clear coat and oxidation. Each of us would polish it with their developed process. They we would judge the result of the polish like a panel of figure skating judges; look at the panel and then hold up a number 1 to 10. I bet there wold be quite a bit of differences between the panels. Maybe I am not good at achieving a "perfect polish".

I'll keep working at it.

David

[Melody Ranch]

A couple things...I don't think you can do a good job of compounding with the method or tools you mentioned....as a matter of fact...I am positive of that. And, you did not mention stripping again. You have to get that covering off and out of the way. I suggest you look thru this site for techniques in polishing...YOUTUBE also has "some" videos which may help. Caswells and Jetsco both have good info..

[InsideOut]

Originally Posted by dbj216

Each of us would polish it with their developed process....I bet there wold be quite a bit of differences between the panels.

I agree 110%. They almost all look better with some amount of polishing rather than failing, splotchy, milky clear coat. Some just stripping the clear coat is "good enough" others aren't satisfied until they have a 10-foot or 5-foot trailer (a trailer that looks "perfect" at that distance).

Good job so far!

Shari

[dbj216]

I have tried everything in my garage to remove the blotchy shadows on my polish job. Lacquer thinner, kerosene, corn startch, Windex, Fantastic, brake cleaner, diesel, gasoline to no avail.

I noticed something interesting when doing my propane tank cover last weekend. I was in the garage under florescent lighting. I was working the aluminum with "C" grade and getting pretty good results. Then I switched to "S" for the final pass and there came the blotchy shawdows. I could see them in the lighting. I stopped after just doing one side of the tank cover. It appeared to my the "S" caused the blotchy shawdows.

Today I was messing around and tried Mothers Metal Polish used for aluminum and mag wheels. I rubbed it on a blochy area and my golly it removed the blotchy spot. I don't feel any grit in this product like I do with "C". But I don't feel the grit with "S" either.

Anyway, I will experiment more with Mother's wheel polish and see if I can't clean up some of the blotchy blues.

David

[dbj216]

Mothers Metal Polish is helping to remove the blochy discoloration. Even though Mothers turns really black as I work the product on the surface, I wipe it off with a paper towel, then scrub with terry cloth and corn starch. The resultant surface is less blotchy. It doesn't get it all by any means, but it reduces it maybe 25 percent.

David

[walt c]

David,
Like you,I tried everything you did PLUS and I still get the blue shadows in "new" metal on my Bubble's door. Tom at Perfect Polish recommended using an acid wash(Alumprep 33) to cure the problem. Well, I did and was all smiles until I fired up the cyclo with "S" and they came back! The only thing that seems to remove the shadows is Nevr-dull(buffing off with a cyclo),but it provides no skin protection after use. Currently,I'm working other projects before trying again....I may just Nevr-dull the metal and coat it with Nufinish polish. Please keep me advised as to your findings,I'm struggling here in Tulsa,BIG TIME!.....walt

[dbj216]

I confess that I was "compounding" with "S". I would move my polisher in circular patterns thinking I was a "random orbital" machine. I don't have an orbital polisher like the Cylco. They are expensive, and how effective can a tool be that just rubs back and forth?

I may not have been clear on the stage of polishing I am at. Sorry.

Well I was looking in an automotive tool catalog at Dynabrade 8" Random Orbital Polisher. The description states "works without leaving haze, halo, or swirl marks".

So, do folks who polish Airstreams see blotchy shawdows, or haze, after compounding? Does random orbital polishing make this haze go away?

David

[dbj216]

There are several threads on "shadows, haze, blotches, shadows, discoloration" in the polished aluminum. I wanted to report my observations a year later.

I believe the S compound is best at creating the blochy areas. I think the carrier for the polish is just difficult to remove. Most solvents and cleaners just smear it around for me.

Nuvite says to clean the residue with corn startch and microfiber towels. Nuvite likes the water spot protection the residue provides, at least for a month or two.

I have noticed my blochy areas disapear after several weeks in the weather. The surface isn't as shinny as just polished, but it is still pretty good.

I read some folks like their final polish pass with F-7 instead of S using the Cyclo. I may try this next year as the S just isn't as good at removing water spots and bird stains. The Cyclo F-7 result is good enough for my old trailer. It ain't a show piece.

For me, the bottom line is not to worry about the blochy haze or shadows. I noticed they went away with time. Then I cleaned and applied a coat of polymer sealant and went traveling.

David