Ok, so your engine covers are in desperate need of attention. First you think, paint, but having a full winter to work on the project you commit to polishing them. Now the question is what do you need and how is it done. Here’s a quick way to get those cases to bling!
First, get yourself an intern! Then get a good bench buffer. The 6” models from places like Home Depot or Lowes are ok, but will take you twice as long to get the result you want. Try to get at least an 8” 3/4HP 8amp unit (1hp is the real deal). Trust us, you’ll thank us later. A bench grinder motor will work fine too. There are a ton of sites on how to set-up your own polishing motor from used dryers, washers, etc. Whatever you use, make sure it is no less than 3400 rpm, anything less isn't possible for polishing.
Next get some wheels and buffing compounds. We use a sisal wheel, spiral sewn and a canton flannel wheel along with some emery compound, Tripoli compound, and white rouge. For final finishing I like the Autosol polish as well. All supplies can be ordered from www.eastwood.com. They have a real good supply of buffing and polishing gear. Your local hardware store will have some too. You’ll also need some good wet/dry sandpaper, I like to have all grits on hand, from 220 up to about 1000. And lastly get a can of aircraft stripper and some rubber gloves. This can be found at any automotive parts store.
For this scenario, we’ll use an engine case that’s in really bad shape. The cover has a deep gauge in it, and as you look closer the finish also has a coat of that old yellowed clearcoat on it, and to top it off, the aluminum is badly oxidized from sitting for the last 30 years.
First thing we need to do is remove the clearcoat with the stripper. Put your gloves on and be careful with this stuff, it will chemically burn your skin instantaneously, trust me, I know! First, scrub the part with some very fine steel wool to break the surface, it allows the stripper to sink in under the clearcoat better. Spray the part thoroughly and let sit, you'll see the clearcoat start bubbling almost right away. After about 5 minutes just brush it off with the steel wool and wash the part real clean.
Now the sanding begins. If it weren’t for that deep gauge you could go right into the cutting, but we need to try and get rid of it first. Start with some 400 grit. Wet sand until it’s gone. If the rest of the part is ok, you can move to 600, then 800 throughout the entire part. This could take some time and will be messy, so have at least a 6 pack nearby! (Depending on how deep the gauge is you may have to start with lower than 400 grit.)
Now we’re almost ready for the fun to begin on the buffer. But before you start here’s a few setup tips;
Wrap a towel around the base of the buffing motor, maybe duck tape it down so it doesn’t get caught up in the wheels. Also put an old blanket on the floor and on the bench, believe us here: The buffer will at some point grab the part and cause it to FLY OUT OF YOUR HAND, it will happen!
Use cotton gloves, the oils from your fingers will drastically alter the compounds effectiveness. I have a few different sets of gloves, one for each wheel. Nothing sucks worse than having to go back and forth to take out emery scratches. ..well parts flying out of your hands sucks pretty bad too.
Use only 1 compound per wheel, NEVER, EVER, mix them. Use a sharpie and label your wheels.
If your part gets too hot, let it cool. A cool part polishes much better and the compound won’t cake up. Alternate your parts while letting each one cool by a fan.
Put compound on the wheel often. How do you know if there’s enough on? When you feel dusty-like bits touch your face and you can’t help but wipe, then it's enough. Make sure you’re wearing safety glasses of course.
And MOST IMPORTANTLY, aluminum oxide is a direct cause of Alzheimer’s disease so wear a mask or wet bandanna always when sanding it or polishing!
First step, use the black or 'emery' compound and that new 'sisal' wheel. This process will remove any leftover oxidation as well as the small scratches left by the sandpaper. The compound will 'cut', but don't expect it to do a lot real fast. Take your time here and DO NOT push the part against the wheel very hard. Get a feel for it and be careful not to feed any irregular angles into the wheel or it will launch! Keep cutting until you have even color and all scratches are gone. Don’t expect or try for a mirror finish just yet. Also remember to let the part cool down from time to time.
Now the Blingn’ begins! Move to the tTripoli compound and a 'spiral sewn' wheel. But first, clean your part. The best way is to wipe it with a clean cotton rag and some all-purpose flour. The flour soaks up oil microscopically, and doesn't scratch the surface. Again do not push hard into the wheel and take your time. Sometimes if the oxidation is not too bad, and if we sanded up to 1500 grit we can start with Tripoli instead of emery. But if there’s oxidation emery is a must.
Tripoli finishes are pretty good for most people including the crew here at DCC. We like it because it gives us the vintage feel and look we like for most of our bikes and it's real easy to maintain. But if you want a real mirror finish, move onto the white rouge.
This final step is where your part will emerge with some serious professional looking results. This part is called 'coloring', as opposed to buffing. You'll need the white rouge compound and the canton wheel. Again, clean your part with a cotton rag and flour before starting. With rouge, you need very light pressure on the part, and don't let the part get hot! It’ll change the color of finish and not get you the results you want.
In some cases you might need to break out the Dremel to get into the tiny areas that can't be reached with the buffing wheel. Use the same steps with the small buffing wheels on the Dremel which can be had from any local Home Depot or Lowes.
You’re part should have a mirror finish now! If you’re happy with it, finally use the Autosol, once the part is completely cooled. The Autosol will basically give the part a final cleaning and leaves a protective film to help prevent future tarnish and makes it easy to clean and buff while on the bike every now and again.
- Herm Narciso