Letter 41383

BUFFING THE SIDES OF ALUMINUM BOATS [Washington] 

July 5, 2006

I WORK AT AN ALUMINUM BOAT FACTORY, WE HAVE ABOUT 2 BOATS THAT COME THROUGH THAT NEED A HALF SIDE BUFF. I WAS TOLD TO USE 500 GRIT FIRST AND THEN 800 GRIT SAND PAPER. THEN WE USE A DEWALT ELECTRIC BUFFER WITH COMPOUND AND THEN WE USE MOTHERS. AFTER I DO THAT THERE IS STILL A CLOUDY EFFECT. WHAT CAN I DO TO GET RID OF THE CLOUDINESS?

THANK YOU

JOSHUA W. GEHRIG
BOATS - CLARKSTON, WA, USA

First off the cloudy effect, most likely is the corrosion that is still on the aluminum. I assume that this boat was in the water for quite some time. Take one square foot of your sheet. Take a 120 grit sandpaper with a little bit of vegatable oil on it, and bring the aluminum to a shiny finish (all the same color). Then do a cross 120 and the 180 grit to remove all 120 grit. Do this until you work your way up to 500 paper (use oil on every step). Then buff with red (Tripoli [link is to product info at Eastwood]) compound you can buy at you local hardware store (don't give up....it is a lot of work).

Happy Polishing,

Trent Kaufman electroplater - Galva, Illinois

If it is oxidation, an aluminum brightner (acid, availble where they sell pressure washers)will strip it off and out of the pores of the metal. However, that's not your problem, Mother's Aluminum Polish [link is to product info at Amazon] is like 80 grit to a fine finish, and the hazing you are seeing is what is left from the bonnet motion and the hand rubbing motion literally laying scratches in the finish.
For buffing, try a yellow, 10x3 16ply airway buff on an angle grinder, 5000rpm, then follow with white, untreated 10x3 airway using slower rpm, 1500to2500 or mount up a loose flannel, 2 20 ply 12" centerless will work well. Buff gently blending your buffing lines together to form basicly one big buff line that the eye doesn't see. Use your brown, tripoli for cutting, you can also use it for finishing or go to a white or green brick for an even finer finish. You can then follow up with a hand polish, I would recommend the two step Flash polishes available at www.infinish.com This can all be done right off the mill finish and little to no sanding is needed. You can use a 320 DA sander where you need to remove a scratch or smooth a weld etc.
This is basically how the dump truck boxes and fuel tankers are done. Also, I have been doing this process, on boats etc. for 14 years now and it works well once you get a system figured out. Good luck.

Dave Barr
- Centralia, WA, USA

Here is sometyhing that I found out when taking a painted aluminum boat down to glass finished aluminum. First of all don't try to do this as you will go nuts. Second, the hazing you have will continue to show up as long as you have any residue on your polishing towe. or bonnet. I have taken aluminum down to a 2000 grit wet sanded finish only to find the haze still present. A gentleman in my town whose business is polishing aluminum down to mirror finishes ( he wouldn't even think of doing my boat when I asked) told me to use corn starch on a clean, dry towel after you are done polishing and it would take off the haze without having to change towels or bonets every 30 seconds. It does work.

Douglas Yeggy
- Chico, CA

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