"Chrome" Brightwork - Theories/Results

[Strife]

There has been a lot of discussion about brightwork on various boards - how or even if it can be polished. I have a theory, and I put that theory to practice with excellent results.

Here is my theory (not a statement of fact)

Brightwork is NOT chrome-plated aluminum. I think it is an aluminum alloy, but mostly aluminum. Aluminum is inherently fairly soft; also, aluminum oxidizes. It doesn't "rust" like iron and disintegrate over time; iron oxide is pourous and allows more water in for additional oxidation. Instead, aluminum forms a skin of aluminum oxide, and once formed, further corrosion and damage is greatly inhibited. This process, under clean and controlled conditions, is what is deliberately done when aluminum is anodized; dyes are added to it to give it color (i.e., red, black, etc). Many times, it is left clear. DC electicity is used to speed up the oxidixing process.

Ironically, anodizing aluminum properly is difficult; even the slightest film of oil, grease, or contaminant will not permit the oxide to form properly or at all, and this is why parts to be anodized must be made completely grease-free and spotless first.

Ever notice that brightwork looks good on a loved and maintained 40-year old car and terrible on a 5-year old poorly maintained and unloved car? This is probably because the loved car has been waxed, or even simply kept "touched" by greasy human hands over time, preventing the oxide formation. On the "unloved car",effectively, the aluminum has become clear-anodized - unfortunately, it was not in a controlled environment and dirt, etc is trapped in the layer of AlO2. This is why it looks so shabby (blotchy white spots, etc) compared to the front panel of your nice home stereo, etc.

I'll bet that waxing brightwork even twice a year would forestall damage indefinitely.

Ordinary metal polishes you can get from the car shops will NOT remove aluminum oxide, no matter how hard you try. You cannot just wax it off. Alumininum oxide is very tough and hard, as is the bond between it and the aluminum underneath. Look at the back of a sheet of sandpaper - aluminum oxide is used in wood and metal sandpaper! Anything you would use to get it off would cut through very thin chrome plating and paint like butter.

So, I decided to fight fire with fire. As a demonstration experiment, I used 220 grit "wet-or-dry" sandpaper, wet (and made from aluminum oxide, of course) , to sand a very old front drip rail for a 107SL. This, of course, made it look a lot worse initially. You can actually see the "skin" come off - this is the tough oxidized layer. Don't go much further because once past that, aluminum is removed quickly. I wiped the rail off frequently to see where I was. Then, I sanded again with 400 wet-or-dry, wet. Note that scratches and even stone dents can be removed this way, although you need to decide how far you want to go down.

Then, I used a mandrel, a "hard" cloth buffer from Lowes, and some "green" and "white" polishes from Lowes on the part. I mounted the wheel in a drill press, and carefully buffed it out (read the instructions with the buffer on proper and safe buffing techniques - mask, glasses, positions of buffing on wheel, etc.). I had to spot-sand and buff several times to get places I missed. Your final "color cut" should be with light pressure to remove any remaining swirl marks. Note that pressing hard is not required and should not be done; you risk bending the part. Let the polishing compound work!

The results, shown below-one not done, one done- speak for themselves!! I also did the rails actually mounted on my 107 this way with excellent results(removing/installing these and the pillar post gaskets are a bear).

I wish I had more confidence in my brightwork-removal skills and know-how. I'd love to do all of my car this way but I don't know how to SAFELY remove brightwork without damage. Needless to say, this is MUCH cheaper than replacement, if you have more time than money. I wish someone would post how to remove the hardtop rails, etc. Maybe this could be done on-car with a drill-mounted buffer and duct tape masking at a very high risk.

Comments? BTW, I didn't actually need these parts, I bought them on eBay. One of them was removed by an IDIOT and the screw holes were slightly ripped although still capable of holding the part to the car and not visible when installed. If anyone wants them (very cheap) let me know.

[TX76513]

Good thread. I have long speculated that metal finishes (non chrome) are "coated" with a protective finish after the mfg. process. The protective coating detoriates with time causing the oxidation. I used to spend quite a bit of time with "Mothers" aluminum polish doing drip rails and such but have moved to a commercial de-oxidiser of Pottasium Hydroxide. Tooth brush application of drip rails and rinse - 10 minutes - gleaming finish. I use a soft bristle brush for alum. wheels - friends are astonished with the result after a 30 second application and hose off.

[kutz]

Hi, I was gonna clean my entire car and for the chrome parts I was thinking of using a chrome cleaner and then polishing it with the Dremmel polish kit that I got with the tool as a nice speed. I've done some aluminum polishing with the Dremmel (not on cars) and it shines a lot.

Will post a pic of it after. Thanks for a good post.