[Hallicrafters] Wrights Brass Polish

[John N. Schwartzberg]

Hello gang -

>-- Read somewhere (R-390 reflector, I think) that ammonia is bad for
>brass structurally.

Like most things in life, the real answer is "it depends."  Ammonia and 
ammonium ions can be corrosive to some copper-based alloys, depending upon 
composition and microstructure, in some high concentrations and 
temperatures.  Buffered and dilute solutions should not pose a corrosion 
threat if used for typical cleaning/polishing applications, and if rinsed 
reasonably well afterwards.  I have used several similar products on Drake 
chassis and other brass/copper stuff with no evidence of corrosion.

>   Somehow it can weaken brass gears and bearings,
>making them more brittle and subject to wear.  I don't know if this is
>so, or to what extent, etc.

For all intents and purposes, this is urban mythology.

>Will shining your belt buckle with Brasso
>will eventually cause your pants to fall down?  I think someone might
>have noticed that phenomenon by now.
>
>-- Really strong chemical cleaners, like Tarnx, are said to get things
>bright and shiny right away, but by virtue of stripping the metal, cause
>much more rapid oxidation thereafter.  Also, some of these products
>consume some metal along with the oxides, and might be a bit dicey on
>plated surfaces.

All true.  Copper alloys, brass alloys, aluminum alloys, and stainless 
steel alloys self passivate, meaning that immediately upon contact with 
oxygen from the air, they form a metal oxide layer on their surfaces.  The 
oxide layer grows in thickness until oxygen molecules can no longer 
penetrate the oxide layer via diffusion, and the reaction rate for forming 
metal oxide slows until it essentially halts.  When the oxide layer is 
removed, scratched, or abraded, the process begins again.

Products for removing tarnish often do so by means of a reduction reaction, 
in essence reversing the oxidation process.  Some are abrasive, and can 
remove minute amounts of metal that way.  Others further oxidize fresh 
surfaces to induce an oxide layer.  Some can be aggressive enough to damage 
plated surfaces, which tend not to be too thick.

>-- Ionizing cleaners, such as Simple Green and 409 can soak into porous
>insulators like phenolic and ceramic, leaving salts behind which can
>result in arcing.  Doubtful that Wrights also has this property.

I've never analyzed the surface of something cleaned by Wright's, but I 
doubt that anything left behind would be deleterious.  Rinse well with 
water.  Rinse again with de-ionized water or distilled water if you're 
really happy about the process.  Dry well.  Live life.  Have fun.  Donate 
something to someone who really needs it.  Save a whale.  You'll feel 
really good.

John


John Schwartzberg
N0GII
Denver, CO

jschwart at ix.netcom.com