An obvious conclusion for me is how I finish various metals each one responds best to mostly one product. I have a bag or three of Aussie pennies over the years they used different metals at the mint obvious when I go to polish them, just had an outstanding success used ten products one shone through
I then used a spray laquer to preserve the shine. I used to make numbers of pens in aluminium air guns drilled out the aluminium was powder coated this seems a way to go.
Peter.