MC How-To

Step by step: From general maintenance to complete restorations, we share tips and tricks for working on classic bikes.

Tips for Successful Metal Polishing

3/12/2012 12:22:03 PM

Tags: how to, bikemaster

1983 Laverda RGS clutch cover 

 
I've never been a particularly patient person, but I'm learning. And nothing helps teach patience like a project that demands patience. Take metal polishing. On the surface (pun intended) it seems like a simple proposition; clean the surface first, slap on some polish, work it in with a clean cloth and voilà, a perfectly polished and gleaming surface results. Unfortunately, when you're working on old iron, it's not always quite so simple.

On the bikes we regularly work on around here — mostly an odd assortment of 1970s to early 1980s Japanese and European road bikes — the major issues we see with metal surfaces are pitting and surface degradation from constant exposure to the elements, and — especially on mid-1970s Japanese bikes — hazing of polished engine cases with clear-coat finishes.

Surface degradation from exposure is a problem experienced by all bikes that see regular use. It can easily be kept at bay by simply cleaning your bike after every ride, or at least every other ride. A quick wipe-down of polished surfaces, followed by waxing, will add years to metal and painted surfaces, protecting them and staving off mild oxidation. It’s a best practice we know we'd do well to follow, but often don't.

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While getting a good sheen on our clear-coated engine cover — the subject of this issue's How-To — we learned one very important lesson: Successful polishing takes lots and lots of elbow grease.

There are, unfortunately, no magic fixes. There is no one product that miraculously cleans and restores neglected surfaces, returning them to a brilliant luster with little more than a light rubbing. The hard truth is, once a surface has diminished significantly it takes work, and a fair amount of it, to restore that surface back to its original sheen.

Our clear-coated but faded engine cover (the clutch cover from editor Backus' 1983 Laverda RGS 1000) would only return its sheen after lots of labor. We tried other methods first, but hand sanding was the only thing that worked. Chemical strippers, which we figured would work great, were surprisingly ineffectual. We found that wet-sanding with 400-grit wet/dry sandpaper before moving to polishing compounds for a final polish worked best, and we should have gone to a final 600-grit for a really spectacular finish. A good polishing wheel was also critical, as was, well, patience.

It's important to appreciate that there is no one way to clean and polish. There are things to avoid; harsh chemicals don't seem to offer real advantages, and possibly place your health at risk. And there are protocols; start coarse and finish fine. For instance, on tough jobs, first wet-sand the surface with 400-grit, followed by 600-grit to remove any sanding marks. Follow up with a polishing wheel, starting with a brown compound, then a white compound, then a final finish with a hand polish. Over time, you’ll develop your own processes that work best for you.

After thoroughly cleaning our engine cover first, we tried stripping off the old clear-coat with a commercial paint stripper, figuring that should work well as clear-coats are usually a lacquer finish. 

After thoroughly cleaning our engine cover first, we tried stripping off the old clear-coat with a commercial paint stripper, figuring that should work well as clear-coats are usually a lacquer finish.

Unfortunately, that hardly put a dent in the clear-coat. It did, however, soften it enough to allow us to scratch some off with a fingernail. 

Unfortunately, that hardly put a dent in the clear-coat. It did, however, soften it enough to allow us to scratch some off with a fingernail.

Next, we tried a medium-grit green scuff ball on a high-speed drill. While this has worked well with raw aluminum, it wasn’t effective on our clear-coated cover. 

Next, we tried a medium-grit green scuff ball on a high-speed drill. While this has worked well with raw aluminum, it wasn’t effective on our clear-coated cover.

Next, we tried sanding with 400-grit wet/dry. Fill a bowl with water and add a small drop of soap. The soap keeps the sandpaper clear when you dip it in the water, and the water lubricates the sandpaper and keeps it clear while you’re sanding. 

Next, we tried sanding with 400-grit wet/dry. Fill a bowl with water and add a small drop of soap. The soap keeps the sandpaper clear when you dip it in the water, and the water lubricates the sandpaper and keeps it clear while you’re sanding.

Now we’re getting somewhere. It took about 20 minutes to get to this point, and the dull parts show we still had a ways to go. 

Now we’re getting somewhere. It took about 20 minutes to get to this point, and the dull parts show we still had a ways to go.

Once we had the entire cover sanded, we rinsed it thoroughly and then put it to a Sisal buffing wheel, using a brown compound. The results were immediate and impressive. 

Once we had the entire cover sanded, we rinsed it thoroughly and then put it to a Sisal buffing wheel, using a brown compound. The results were immediate and impressive.

While buffing, clean your buffing wheel regularly. 

While buffing, clean your buffing wheel regularly. Metal gets bound in the compound and can abrade surfaces more than you’re looking to. A simple trick is to wrap a hack saw blade with duct tape and carefully stroke it across the spinning wheel.

After buffing our cover with brown compound, we used wadding polish to remove all the wax before giving a final buffing using white compound. 

After buffing our cover with brown compound, we used wadding polish to remove all the wax before giving a final buffing using white compound. You can see the finish is really starting to come up.

Once we finished with the buffing wheel, we hand-polished the cover with Mothers Mag & Aluminum Polish to get a nice, even luster. 

Once we finished with the buffing wheel, we hand-polished the cover with Mothers Mag & Aluminum Polish to get a nice, even luster. There are still some visible scratches, suggesting we should have done a finish-sand with 600-grit. That’s a lesson we’ll remember for the next time.



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Post a comment below.

 

waspfarmer
11/13/2013 5:28:49 PM
I find it helpfull to use the wheel with smooth light pressure strokes one "line" across the piece overlapping the previous pass. A 3500 RPM table-mounted grinding wheel (fitted with a Sisal type polishing wheel, one for each grade of compound) is a sound investment and will save hours of time and elbow-lube. The next series of passes is applied at 90 degrees to the previous. Use light pressure letting the wheel and compound do the work and avoiding excessive heat buildup that can warp the piece. A wet terry cloth towel and/or a bucket of water for quick cooling dips is handy. Patience is key. It will take four times longer than you initially expect! Also, this is the time to true and flatten joints on covers by sanding in figure "8" motions on a glass plate ore machinist's table. I trued my valve cover joints by sticking 400grit wet/dry paper on the angle-table of my drill press as it's nice and flat. My Brit is oil-tight... ish. It's easy to clean a polished surface later with a simple hand buff-up with "Mother's", so I don't use a sealent or clear-coat.

peggy83583868
4/6/2013 3:37:25 AM
Iv done a lot of buffing out parts on badly scratched cases i start with 220 grit 320 400 600 800 1000 then i go to the buffing wheels i start with the grey compound on a sewn cotton wheel then i go to the white compound on a loose cotton wheel its a lot of work but it pays off in the long run with a mirror like finish

gerald estes III
4/4/2013 1:14:56 PM
ride 'em dont hide 'em....never, i repeat never submerse a carbureator into a cleaning solution. i helped out at a dealership one spring...they offered indoor winter storagfe to many of their customers who purchased "vacation home scooters'...the staff mechanic's/service managers procedure was to dip the carbs...i got there a couple seasons later and found the zinc castings resembled concrete cinder blocks covered with lichens - go figure.

gearjam
3/29/2012 9:37:39 PM
After purchasing a 3/4 hp buffer and buffing kit, I have not only done my own pieces-but, have started branching out to other parts for members of our bike club. It really is gratifying to take a part that wasn't fit for the dumpster, and have people compliment me on it. Takes a lot of patience, detail, and practice to make it come out right. There is a reason that top polishers like Carpy charge so much.

Steve Allen
3/22/2012 1:32:39 AM
moto1classics Says polishing aluminum is like sanding really hard wood. If its real rough start with a 220 grit then 300 -400 - 500- then finish with a 600 untill all the scratches are gone.Then Polish.

RICHARD BACKUS
3/16/2012 10:29:24 PM
Daniel. No, I didn't seal it with anything else. Yes, it means frequent light cleaning and buffing, but that's okay. Also, Chip commented about how parts can be flung to the ground; too true. I always make sure to have a rubber floor mat below the polisher. Richard/Motorcycle Classics.

daniel reiss
3/15/2012 7:28:20 PM
Is the aluminum polish, the final step of the process...or did you seal it with anything else?

Jack Jason
3/15/2012 4:16:30 PM
Another pair of reasons to wear gloves- they will keep the oil from your fingers getting on the piece, but more importantly they will allow you to hold the piece as it heats up. Heat is a polisher's best friend. It says the compound is working to remove the smallest of scratches and pores from the metal, yielding a high gloss. The hotter the better, so I'm not sure if cotton is the way to go. I wear leather.

jordan grant
3/15/2012 2:38:16 PM
One last tip....buffing companies sell white cotton gloves made specifically for buffing.You can wipe you item with them instead of grabbing a rag.They will also protect your hand or at least keep your severed finger in the glove for reattachment....Your finger wont follow your piece across the room.Dont ask me how I know this....

jordan grant
3/15/2012 2:34:53 PM
I too have enjoyed the learning process of successful polishing of vintage bike engine cases,and I still dont do the every ride cleaning to limit having to do it again soon!.That is laziness writ large !.POR15 has a two part product they say eliminates rebuffing .Its a cleaner and then a coating but supposedly keeps the buffed look and not the "coated" look.Havent tried it yet but this co has a lot of superior products and is respected in the bike and car restoration fields.Havent used it yet but have purchased it.Film at 11 on the results....Jordan

Chip Haehnel
3/15/2012 12:36:20 PM
Wheel polishing will take the piece out of your hands. Practice with something that can be flung to the floor or wall and broken without regret. I have used a composite wheel chucked in a heavy duty hand drill motor as a substitute for a more flexible wire wheel to remove old finish with little damage to the old metal. I agree with the author, there is no 'easy way' to return the shine. Magnesium parts are different and should be researched before chemical or mechanical means are used to bring them up to a standard.ch

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