<VV> Polishing Trim Pieces

[Tony Underwood]

At 03:49 hours 12/14/2004 -0800, bmooers@farniente.com wrote:
>What is the best method for polishing up old aluminum trim pieces? I have 
>oxidation on entry sills, bezels, other trim etc. Any ideas, products etc? 
>Thanks - Bruce      



If the trim is anodized, there's not much of any sort of polishing that can
be done.    The anodizing is a very hard coating which simply will not
polish up since it's not metallic, it's an oxide formed on the surface of
aluminum by immersing it in H2SO4 and running an electric current through
it so as to leach aluminum ions out of the surface and leave clear hard
aluminum oxide behind.   If you have aluminum trim on the car which isn't
anodized, you can polish it with a variety of stuff, for instance Dupont
"White" polishing compound.   Some sill moldings are raw aluminum and can
be polished until they gleam.   Headlight bezels will not.   Most car
polishes simply cloud them up since the anodizing tends to decompose with
age and exposure to the elements and eventually dulls, presenting lots of
tiny nooks and crannies for wax, polish and of course plain old dirt etc to
lodge and "cloud" the trim piece, requiring much cleaning and still end up
cloudy and dull.    

Now:   

There are ways to freshen up the anodized coating if it dulls with age.
One way is to simply scrub the parts ferociously with a good soapy cleaner
and rinse them thoroughly with water, then wipe them down with lacquer
thinner to remove any remaining oils or other such petroleum
contaminants...  and then spray them with your favorite brand of
professional grade acrylic or urethane clearcoat.    

A better way of cleaning anodized aluminum is to wash them in soapy water
as above and then give them a soak in straight/concentrated nitric acid.
This is sometimes called "Brite-Dip".   You  might have a little trouble
finding a source for nitric acid since it's extremely caustic and a bit
hazardous as well as being useful as a base compound for making explosives
so it's probably regulated these days.    I haven't been keeping up with
such...  It is *Extremely* rough on skin or anything else organic so do NOT
 get it on you... your hide will quickly turn pale pink then yellow, then
green, and then it will harden and slough off.   You need not ask how I
know.   Don't do it.       

One more note:    Don't get it on any ferrous metals.   It reacts
unfavorably with iron or steel, corrodes it quickly and efficiently and
thoroughly.   A few minutes in nitric acid will make a chunk of cast iron
look like it's been exposed to sea water for several years.   Even hardened
steel turns to mush when exposed to nitric acid.      

However, nitric acid is the very best aluminum cleaner I've ever seen.
The aluminum comes out of the acid nice and bright with all tarnish and
surface "rot" removed and bright metal shining, including anodized
aluminum.    This is where it gets washed thoroughly, dried, and then shot
with your favorite clear coat.    Been there done that often, the stuff
stays bright and looks as good as it's ever gonna look without stripping
the piece of all anodizing and polishing then clearcoating or reanodizing.    
      

One way to see what the trim piece would look like after clearcoating is to
clean it thoroughly, degrease it, clean it again, then rinse it with water
containing a little dishwashing detergent to serve as a wetting agent and
"skim" the surface over.    That's what the piece would look like
clearcoated.    It indeed makes a difference in how the piece will look,
sometimes rivalling stripping/polishing or reanodizing.   As mentioned,
I've "supercleaned" and britedipped anodized aluminum and then clearcoated
it and it looks quite nice.    


You  should be able to find a place in town that offers "brite-dip"
cleaning of aluminum.   You could then wander down to your favorite paint
and body shop and leave the parts with them so as to have them clearcoated
next time they clearcoat a car.   Should be quite cheap that way.     If
you're lucky, perhaps the place that does the brite-dip can clearcoat the
piece as well.    Check around.   


Now, if the trim you want to polish is stainless steel, like early Vair
belt trim, it can be hand polished with compounds available at your FLAPS.
   



tony..