Pitting in the skin

[Stan Drury]

I have been polishing a 1959 flying cloud and to cut through the heavy tarnish I've been using nuvite F-9, F-7 and caswell gray rouge sticks.
It looks pretty good from a distance but up close the top panels are very
pitted. The sides are much better. It almost looks to me as if something like acid rain has eaten into the finish. The nuvite can't take them out. Has anyone run into this while polishing a heavily oxidized airstream?

[Melody Ranch]

Hey Stan...Under the polishing Forum thread you will see some posts on the agony I went thru with my 56 Calif. Flying Cloud. It sat on a roof top in Hollywood/Santa Monica for many years...the smog and beach moisture did make its own acid rain. I finally resorted to black Caswell bars, then brown and then to F-9 and G Nuvite. I compounded to the point of concern about the alclad ....it was OK. The best I could cut/compound for results was with wheels...and I hate to say it....the sisal wheel at that. Really aggressive. I still have pitting but not as bad as what you show.....but mine was as bad when I started. Maybe you can try what I did. Good luck.

[scorpiontimo]

Melody is right, with mine the rig had made several trips to Alaska before the 80's no rock guards and about 10 decals on the front 40+ years latter she needs a polish humm, you need to get aggressive f grades did not do it for me the bar is what did it finished off with s grade not perfect but I can live with it make sure you clean the area while doing this and clean a lot them pits harbor small stuff that will keep cutting when you want to go smother, good luck and be patent.

[perryg114]

You might try wet sanding with emory paper. I expect you could start with 400 grit and see if that cuts most of the pits down then go finer with the emory and then start with your compounds. You need to get the surface smooth or nearly so before you start with the compounds. There is the concern about removing the alclad and that is why you want to do a small area to see how deep the pits are. The metal under the alclad will polish but the color will be more gray than the alclad.

Perry

[Ganaraska]

If you have to sand out bad pitting a random orbital sander will make short work of it and leave the least scratches. Start with fine wet or dry paper, say 600 and see how it works. If not aggressive enough you will have to go to 400. Then work your way down to 600 then 1000 till it is smooth enough to polish.

[Stan Drury]

Thanks for that idea , so far I have done some hand sanding with 400 grit
emory paper. It did help and after cleaning with mineral spirits it looks better, from a few feet away.
I'm going over the rest of the trailer with nuvite C now but I'll try the orbital sander on top where it can't be seen, after I'm done. I do worry about going thru the alclad with a powered sander. I don't know how thick
the outer layer is or how to gauge how deep I can go. I'll post another picture when I get more done. Thanks, Stan.

[Forrest]

Originally Posted by Stan Drury

It almost looks to me as if something like acid rain has eaten into the finish. The nuvite can't take them out. Has anyone run into this while polishing a heavily oxidized airstream?

More likely tree leaves were allowed to sit on the roof. As they decompose acid is released and is trapped there where it eats into the metal.

[Ganaraska]

Go easy with the orbital sander. Keep it moving constantly, keep the pad flat the surface so it does not dig gouges. Hold it lightly against the surface and move back and forth with a slow polishing motion. It will sand the surface smooth.

A trickle of water helps, if you do not have a hose handy a bucket and sponge will work. A little dish soap in the water helps keep the paper clean and makes it work better, longer.

Be careful not to get any dirt or debris under it, it will make scratches, if you see something stop and clean it off.

[scorpiontimo]

I am working on a 61 with many years of being ion the gulf and about every thing mother nature can throw at her, you never know what is under all that grey, what is working for me is a brown bar and not so soft of a buff wheel, the bars can be got at this place Zephyr Sales Company, Home of Zephyr Pro40, Metal Polish, Cleaners, Bar Rouge, Buffing Wheels, Dealer Display Rack, Buffing Kits, Retail Packaging I have been using the air yellow wheels they mount on a side grinder, it looks to rough but it is not I also use the soft wheel from jesco but the brown with about 8 passes has done good reducing the nasty stuff, then a good s grade or Lowe's truck box with orbiter.

[Stan Drury]

Thanks for the detailed information. It is a big help and I'm going to follow up on it.

[bhutch74ly]

I too appreciate all the good information. I recently purchased a 74 TW 25 foot and began working on the skin a couple of days ago. There were several panels with deep scratches probably caused by a rod, bracket or something attached to an awning on the front of the trailer that came loose in the wind at some time in the past. I wet sanded the panels by hand with 600 grit wet paper and then went to 1000 grit. I kept the paper and skin very wet and used some dish washing detergent in the water to keep the abrasive clean. In addition, I made an effort to keep my sanding strokes perfectly horizontal to avoid swirl marks. The deep scratches are still there, but much less visible. In addition the surface has the appearance of brushed aluminum or stainless steel because all of the tiny scratches are linear and horizontal. The surface is too dull to give much of a reflection, but I believe I like the look. I'm thinking about doing the whole trailer this way. This will be a lot less work than a mirror polish job. I can always polish later after I do all the other restoration stuff that needs to be done to make the trailer useable. Also, there were several splotchy,dark areas near the top of the trailer that I suspect had something to do with a tarp or cover that flapped around on the trailer for a long time and wore through the clearcoat. I used a box of Barkeepers friend and wet cloth to get most of these off the skin. Again, I kept all of my scrubbing strokes horizontal. This product is a great cleaner and the abrasive is very, very fine so there was very little, if any, scratching of the skin. As I worked I rinsed with clean water often to remove the dirty material and Al oxide. I'm thinking this may be a very good and inexpensive precleaner to prep a panel for polishing. I'm going to experiment further with this and will post results.

[adwriter73]

Had this problem too and wet sanding with 400 grit took it out, however, it left some fairly deep scratches that are hard to polish out. I'm going to try going back with 1000 grit paper to see if it takes it out with less scratching.