Basics of how to restore aluminium stuff

[ncbugeye]

I was fortunate to purchase some Bugeye sidescreens on Ebay, and they are good value, but they need some cleaning up, since there are lots of minor scratches, scuffs and dings and several places where the PO filled some holes that the PPO had drilled for unknown reasons. The places where the holes have been filled are bumps of weld, fairly smooth, but bumps all the same. I have very carefully tried grinding the bumps away with a Dremel tool but I'm not sure that is the right way - the welded material seems MUCH harder than the base aluminium.

So my question is, what are the basic rules for restoring the surface of aluminium parts to as good a state as possible?

I also have scuffs of the same kind on the cockpit surround trim and the windscreen pillars, so I have plenty of projects on which I can reuse this information in future.

Also, how easy is it to chrome plate aluminium? Is it something that one can do at home, or is that a crazy idea?

One of the really enjoyable things about this hobby, returning to it after a 40 year furlough, is that you have to become familiar with so many basic techniques like this.

ps being a Brit I still spell aluminium the old-fashioned way, even after 18 years in the USA, because these are little BRITISH cars, after all.

 

[jlaird]

First you get the anadozing off with lye or oven cleaner.

Then you polish. Get those bumps with a flat fine bastard file first.

Then you polish, polish, polish.

 

[aeronca65t]

I use Bartender's Friend (a cleaner, like Ajax) and a damp Scotch-Brite pad. Rub, rub, rub. Makes a nice "matte" finish.

Or use Mothers Aluminum Polish (will make it more shiney)You can spray it with a clear spray (polyurethane) and it will stay glossy for a while.

You can't really chrome-plate aluminum (at least not for a reasonable cost).

 

[jlaird]

No but it can be re-anodized, if you need a source let me know.

 

[ncbugeye]

Among my spares I have a pair of Bugeye windscreen pillars which appear to be chrome plated. The chrome is not all that good, there are pinholes, but it evidently is possible. So what are the pitfalls?

 

[Sarastro]

Aluminum can be plated, but it's not done often. I suspect that the real problem is adhesion--last thing you want is peeling metal.

Any alkaline solution will remove oxidation from aluminum. Even just ammonia, if the oxidation is not too heavy. Using stronger stuff, like oven cleaner or lye, can be a little tricky; it's easy to overdo it. A weak solution (say, 25% by volume) of drain cleaner in water might be OK for heavier work. This stuff is hazardous, though; use rubber gloves and be sure to keep it off your skin.

Aluminum buffs out beautifully. Just get a soft cloth buffing wheel, an inexpensive grinder, and medium buffing abrasive. First, if the aluminum is scratched or has a rough surface, polish it out with progressively finer sandpaper. I go up to about 300 grit, then buff, finally clean off the abrasive with naptha and polish with metal polish. It really looks amazing. Of course, it can oxidize again, so you have to keep polishing or waxing it.

Most metal polishes do well on aluminum, too. However, they often don't do a good job of removing oxide. A lot of aluminum has so-called clear anodizing, which is just anodizing without dye. This cannot be polished until the anodize layer (which is just oxide) is removed by dipping it in an alkaline solution for a half minute or so. To determine if it's anodized, try polishing with metal polish. If the polishing cloth comes off black, it's not anodized.

 

[Hap Waldrop]

I rebuild alot of SU carbs, and polish the dashpots. I first clean the aluminum with hot water and soap, then I start with 180 grit sandpaper to get the imperfections out, than work my way down to 400 grit and wet sand , then I polish with a buffing wheel and white rouge, then finish by wiping down with a soft terry cloth.

 

[jlaird]

My oh my Hap. Right from the factory. They are lovely.

 

[bugimike]

Jack beat me to my own thoughts Hap!!!

 

[Roger]

When you get the surface smooth, it's very hard to beat the high speeed buffing wheel and beeswax for a really glossy shine. And it's very kind to the surface.

 

[John Loftus]

Just a quick caution for anyone buffing the dashpots .. don't let them get too hot. I've read stories of people warping them during buffing and the pistons don't slide like they are suppose too. But you guys probably know that.

Cheers,
John

 

[paulsherman]

Same subject parts.
How is the easiest way to clean a transmission casing? It is out of the car. I want to do it the easy way. Spray aluminum wheel cleaner, oven cleaner or cleaner cleaner?
Thank you

 

[jlaird]

Mineral spirits and paint brush to get the grease off, then soap and water, then wire brush on drill then clean again with mineral sperits then paint.

 

[John Loftus]

For the 'soap and water' part I've been using a product that I get at Home Depot called Industrial Purple Degreaser. Similar to Simple Green but much stronger .. mix with water via. directions and then use brushes and scotch bright pads (wear chemical gloves as it will attack skin)to get in all the nooks and crannies. Hose off. After several scrubbings you should be at the point where water does not bead on surfaces. Wire brush as Jack says is real good for removing paint. I wipe down with Lacquer thinner on a rag (mineral spirits seem too oily for auto paint prep) and/or Prep Sol if there are any concerns with silicone contamination (such as Dot 5 brake fluid). Final tip .. if you are priming bare aluminum use a self-etch primer made for aluminum. My favorite is Variprime from Dupont but you need to use a spray gun. Marhyde and SEM have good self-etch primers in spray cans.

Cheers,
John