Any ideas for easy polishing up of old r/b step plates- I assumed they were a zinc alloy but macs and snyders state theirs are aluminum... so tips for both zinc and ally welcome!
Hey John,
Ha, ha....that is, EASY and POLISH is not the way it (polishing) goes

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I just started learning about polishing aluminum mostly (and other metals).
Harbor Freight has a basic starting polishing kit. It contains 'buffs' and several (5) polishing sticks of various colors/grit. I spent HOURS / HOURS attempting to apply what I learned from u-tube videos. It worked

!!
Just do some experimenting until tired/bored, then let it be awhile.
You will get to the point to where you have to decide...how shiny do I want it before I stop...like looking into a mirror or less than ! To me it has become rewarding to see an ugly/oxidized / patina hunk of metal turn into a swan.
You can get a pretty nice start on stuff to use at HF and/or other places i.e.-ebay, etc.
Down side is that it's tough on aritheritic hands and they will tell you when they have had enough for several days. But, if you enjoy making your own results in life, may be for you. I'd show you results of some of my efforts as a neophyte...but do not want to brag and / or blind you
BTW...check past threads. I ask this same question , as John, but over on the early V8 side , not tooo long ago. Guess why I asked over there and not here

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