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Old 03-29-2015, 03:59 PM   #1
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Jestco Buffer Leaving Hazy Streaks

I have polished my 66 Trade Wind Alcad skins with the "Jestco system" using an 8" diameter by 1" wide unsewn cotton buffing wheels and the gray and pink bars. I was looking for a faster polish as compounding seems to take a lot of time. My old trailer was oxidized and significantly pitted in the front as you can imagine. I did not wet sand it.

I rotated the buffing wheel at about 2800 rpm on my angle polisher. I worked in about 12" widths progressing from the bottom of the trailer to the top. I was traversing at a slow rate so the buffer could do its thing, like maybe an inch a second.

I first found streaks where I thought I had missed a little stripe with the gray bar and was hopeful the pink bar pass would clean them up. But it did not. Then I compounded with Airbrite medium thinking that would clean up the streaks, but it did not. And Cyclo with F7 or S does not get rid of the streaks. I would think almost any kind of aluminum surface would polish. Even my brushed finish 86 polished up pretty good.

The S polish sticks in the streaks to the point of being difficult to remove. It's like the streaks are a rougher surface although they don't feel that way. They are hazy streaks against the normal mirror like surfaces.

I wonder if I ground down into the aluminum skin too far by putting too much pressure on the buffer, or traversing to slowly? Have any of you experienced polishers using the "Jestco" buffer method had similar situation?

David
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Old 03-29-2015, 04:47 PM   #2
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We had a similar issue when we polished our 65. We were told we may have burned into the aluminum. We used Jestco and started having the cloudiness issue after using the gray bars. We only had it in a few spots. hopefully someone can share more insight them I can. Good luck
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Old 03-29-2015, 04:49 PM   #3
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Here are a couple of pictures of it finished.
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Old 04-05-2015, 07:44 PM   #4
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It seems to me we ought to give a word of caution to amateur polishers like me. I tried the "Jestco" method thinking it would save time over compounding at 750 rpm. I sure didn't think an unsewn cotton buff at 2800 rpm could cut through the Alcad, but it sure does! My old 66 Trade Wind was quite corroded as you might expect. Dull gray. I did not wet sand first. I found the buffer cut the corrosion pretty good. I was getting a good polish on the first pass. The front corners were pitted as well as corroded. So I spent extra time there, and this is where most of the damage is. I first I thought they were streaks that I had missed, or the polish didn't do very well on. Then I thought the pink bar would clean them up. Then I thought I could compound with F7. Finally I wondered if Cyclo with F7 would blend them some. Nope, nope, and nope.

So I send a word of caution to wanna go fast cotton buff polishers. You can't tell or even see that you are grinding through the Alcad layer. And the layer below it does not want to polish out. You might have a zebra Airstream like I do.

I wonder if others have had this problem. Or did I just mess up big time due to my inexperience with this polishing method?

I am hopeful a season or two in the rain, bird droppings, and ice will obscure the strips. We'll see.

David
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Old 04-05-2015, 08:02 PM   #5
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I had a couple stripes on my '86 where I burned through with a yellow airway wheel. I caught it a bit sooner than you did. Sadly, there's nothing you can do about it....grr.. I used the Nuvite method on my next project....
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Old 04-05-2015, 08:10 PM   #6
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There is some info here....
http://www.airforums.com/forums/f441...rs-107853.html

I have some hope for you, it's possible that you undercast the aluminum. I had some minor spots like this.... They always showed up at waist level ( where I assume I had the most pressure) and where I went to slowly to really work a scratch. I used an aluminum brightener on some of the spots. Polishing in the opposite direction ( horizontally rather than vertically) also helped.

I put pictures here on my moonraker thread here starting at post 400
http://www.airforums.com/forums/f109...ml#post1354093

You can Google Undercasting aluminum, and see if it matches what you are seeing.

Good luck!
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Old 04-05-2015, 08:17 PM   #7
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I've had some similar problems in spots. Mine isn't as extensive as yours though. It seems to me that the condition results from the overuse of the grey bar, and possibly a contaminated wheel. I think most of my damage occurred when I was having a tough time cleaning the wheel. I've spent hours working on a single one square foot spot. I improved it with a quick pass with the grey bar, then working it over pretty good with the red bar and Cyclo. It seems that I reach a point where if I try to improve it more, it just gets worse. I tried some Nuvite F-7, and it looked terrible. I got some new sewn wheels and haven't had any more damage.

I assume you are using different wheels for the red and grey bars aren't you?
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Old 04-06-2015, 06:15 AM   #8
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I was raking my wheel nearly every application of more gray bar. My unsewn wheel did wear down from 8" to about 6" in diameter. I used a new wheel about half way through the gray bar pass. I kept the wheel vertical and traversed in horizontal swipes. I worked from the bottom to the top. The lighting in my garage isn't the greatest.

I'm sure I was "trying to do a good job" on those pits and scratches. Working slowly and letting the wheel do the work. It sure did a job on it!

But the bottom line is buffing wheels can damage Alcad. My 86 trailer is 3003 aluminum. I used the compounding method on it. But I don't think I could cause streaks on this type of aluminum.

Thanks reinergirl for the tip on "undercast aluminum". I'll take a look.

David
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Old 04-06-2015, 06:32 AM   #9
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Your 1966 was clear coated originally. To clear coat they first etch the aluminum then the clear is applied. If it was re cleared, you never know what the previous treatments had done. I use the Jestco system and have found it a successful first step in polishing. You might want to try a white bar and if it is very oxidized try a blue/ grey bar. You also should try ganging another wheel on the Jestco arbor, 2" is better than 1"
you may also be seeing old oxidation. My 62 was never clear coated but has deep oxide tears down the curb side from an awning in a campground.
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Old 04-06-2015, 07:12 PM   #10
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I haven't found information on "undercast", but the description fits my marks well. My 66 was clear coated, but I doubt it was re-coated. It was quite faded and corroded when I purchased it.

I did notice as I Cyclo with F-7 or S the hazy streaks would pick up the polish that would not come off. Even mineral spirits had a hard time getting the black out. Maybe this is a definitive test of gray bar "undercast", or driving polish grit deep into the aluminum.

So if I understand reinergirl correctly, my best bet is to compound the spots with F-7 in a direction 90 degrees to the "scratching" caused by the buffing wheel. I have tried on one of the front corner panels with F-7 and my wool bonnet at 1400 rpm and did not have success in shrinking or removing the streaks. I was cautious as I didn't want to make the "burn mark" worse if in fact I was polishing the Alclad pure aluminum layer off. Maybe more polish and more pressure will bring some success.

I was surprised I could not polish these areas. I've never met a piece of aluminium that couldn't be polished. Polishing is just achieving a perfect "surface finish".

I'll try again with my F-7 and work the streaks a bit harder.

David
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Old 04-07-2015, 10:29 AM   #11
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Jestco Buffer Leaving Hazy Streaks

Having done a fair amount of polishing,,,, I will state with a certain amount of authority that an inexperienced polisher should as a rule avoid the high rpm polishers when dealing with Alclad... (I.e. angle grinders and the like).

I will also state that a novice polisher avoid the inclination to try to polish away every surface imperfection and pit. Is the blemish extends deeper than the Alclad, once "fixed", an imperfection that is all but unnoticeable at five or ten feet can become brutally obvious at forty feet.

Even a low speed purpose built buffer can create enough friction heat to blister the very thin Alclad layer quickly, anything faster than a few hundred RPM can burn almost instantly with just a little pressure.


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Old 04-07-2015, 07:21 PM   #12
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I'm not a metallurgists. Alcoa specs say 2024 t3 Alclad is an aircraft grade sheeting with good strength and fatique resistance. The cladding is 5% of the thickness of the sheet, or about .0015 inch on a .032 inch thick sheet.

I suspect much of my Alclad layer corroded away many years ago. And if I sanded it or heavily polished it, wouldn't the surface under the cladding smooth out and polish up like any other sheet of aluminum?

I haven't figured out my hazy streaks, or if I can reduce their appearance some.

I tried to follow the Jestco process as outlined in their instructions. Polisher set at 2800 rpm, working right to left and working upward.

Here is their instructions:

[Buffing (equipment needed: side grinder, buffing wheels, jewelers rouge, abrasive compound, mineral spirits, lots of rags)

Start at the rear of the camper. Your Airstream will require more attention to the front of the camper because of the pitting and road debris and will usually take more patience than the rear. Use mineral spirits to clean the surface, especially around the rivets. This process cleans the porous metal and brightens the surface.

Start with one of the 8” soft buffs. Apply the grey abrasive compound to the edge of the buff. Polish the surface using the grey abrasive compound with a side grinder/right angle grinder (1800-3600rpm range) Polish an 8 inch square section at a time using moderate to light pressure. Work the surface from the right to left direction while moving the buffer upwards. This will keep the surface cool and produce a smoother finish. After each section apply more compound. Lightly overlap the previous section each time.

After every 4-8 applications with the compound, use the buffing rake to clean out the contamination and soften the buff. (Hang-on tight). I usually mount the rake to a board and lean it up against a wall. (This is definitely the dirty part of the process. Use a strong fan to blow away the dust if possible when raking)

Use mineral spirits to clean the excess compound from the surface, especially around the rivets.

Repeat the above steps (a-d) using the 8” soft buff and the Pink Jewelers rouge.

Use the same process outlined in step (a-d) with the smaller buffs to detail around the windows vents and lower trim areas


I don't believe this is a Jestco process issue, it is something I did in my polishing with the gray bar.

David
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Old 04-11-2015, 11:00 PM   #13
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Quote:
Originally Posted by dbj216 View Post

So if I understand reinergirl correctly, my best bet is to compound the spots with F-7 in a direction 90 degrees to the "scratching" caused by the buffing wheel. I have tried on one of the front corner panels with F-7 and my wool bonnet at 1400 rpm and did not have success in shrinking or removing the streaks. I was cautious as I didn't want to make the "burn mark" worse if in fact I was polishing the Alclad pure aluminum layer off. Maybe more polish and more pressure will bring some success.

David
I think with areas this large you are going to have to resort to an aluminum brightener. It's funny how these areas tend to look okay at the coarser grit and the minute you compound with the finishing grades like c or s they " hold the polish".

I had no luck originally with f7 but I was using a new pad and determined eventually that it just didn't cut enough until it had been used more.

You are going to have your work cut out for you as your areas are much larger than mine. But I did eventually make the disappear.

I personally feel that undercasting is mostly caused by heat.
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Old 04-12-2015, 05:55 AM   #14
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Compounding with F7 with a wheel direction 90 degrees to the hazy streek isn't having much of an effect. Today I will try some more aggressive C.

The "aluminum brightener" that I am familiar with (like for automotive wheels) is a strong chemical that eats oxidation. I'm reluctant to apply an "acid wash" on my trailer. I'm not sure what the chemical is, but likewise I'm not sure what it is that I'm trying to get rid of.

I can understand where the Jestco gray bar compound and cotton buff may have impregnated polish grit in the soft aluminum. I don't know how much heat I generated with the grit and buff. There was no "Caution, buffing with Jestco gray bar may cause "undercast" if not done correctly". I do know the buff picked up aluminum oxide as slowly I traversed across the aluminum. Aluminum oxide is an abrasive in itself. I raked the buff almost every time I "charged" it with more gray compound from the bar.

So if I had my gray bar compound and my buff at 2800 rpm and just left it in one spot, would I grind clear through the aluminum? Would there be enough heat generated that the aluminum would start to smoke?

I'm very disappointed in the results I got using the Jestco buffing method to polish my Trade Wind. I had no idea there was some sort of skill level required; like speed, pressure, raking the buff, etc. My streaks are worse in the front where I had lots of pits from towing. That's the area where I worked the aluminum the hardest.

David
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