[ARC5] Cleaning and "polishing" aluminum...

[Michael Hanz]

Taigh's recommendations are right on.  I've been on a crusade to
eliminate steel wool from the world for the last ten years, and posted
numerous times about it.  Get it out of your house!  There's no earthly
reason for having it for metal restoration, and any bits lying around
are just a temptation to use the stuff.  You'll be sooorrry...  :-) 
Scotchbrite is excellent, and there are other similar non-conducting
products on the market.

To add to Taigh's remarks on Ken's specific question, it depends on what
you are trying to accomplish.  If a geenral cleanup is all you wish to
accomplish, the Scotchbrite will do a nice job.  You'll need to do it
with about three different grades of increasingly fine abrasive,
depending on how bad the original corrosion is.  There's no two ways
around it, unfortunately - you have to get down to the bottom of
whatever pitting there is in the original aluminum.  That's just the
first course if you are attempting to restore it to original finish,
however.  The surface after Scotchbrite might look nice, but it has
millions of fine scratches that opens the aluminum up to much more rapid
surface corrosion.  If you absolutely have to have it looking like a
brand new command set, you then have to polish it to a brilliant mirror
finish, using a good aluminum polish like Met-al.  With that as a base,
you then thoroughly clean the part of any polish residue and dip the
aluminum into a metal etchant - an automotive paint store will have this
if you can't find it at one of the aircraft material suppliers.  A
minute or two in this solution and the part will look like it just came
out of the factory.  If you spray it with a protectant - furniture wax,
LPS-2, even WD-40, it will stay that way a long time.  (If you don't it
will stain with your fingerprints every time you pick it up.)

73,
Mike

Taigh Ramey wrote:
> 
> Please be careful about using steel wool on any aluminum parts. I have
> learned the hard way that when you use steel wool it will leave tiny
> particles of the wool in the pores and pits of the aluminum. Over time
> (a shorter amount of time than you might think) the steel will react
> with the aluminum. The particles will act like anodes and will cause
> dissimilar metal corrosion.
> 
> The problem that I see with cleaning a cover of a 274N radio would be
> the final finish. To get the pits clean you usually need to remove a
> fair amount of metal. The problem is how to restore a factory finish.
> The radio wasn't polished at the factory but that is what you are going
> to have to do to remove the swirl and abrasive marks left from the
> mechanical cleaning process.
> 
> There are Phosphorus based cleaning and etching solutions that will kill
> the corrosion and generally brighten the surface but they don't remove
> the pits they just clean them.
> 
> -----Original Message-----
> From: arc5-admin@mailman.qth.net [mailto:arc5-admin@mailman.qth.net] On
> Behalf Of Kenneth G. Gordon
> Sent: Tuesday, June 25, 2002 8:29 PM
> 
> I want to clean up some really dirty BC-454/455 receivers, the all
> aluminum ones. Very fine steel-wool and lots of elbow grease do a
> good job, but I am getting really short in the elbow grease
> department what with my Rheumatoid Arthritis and all.
> 
> Is there some easier, better way to accomplish the same thing?
> Buffing wheel and compound or some such? I tried using a cotton
> buffing wheel and rouge, but that didn't cut the surface oxidation.
> 
> Suggestions from the collective wisdom gladly accepted...and
> acted upon.