Polishing Gold Filled and Silver
I have some charms that have scratchy marks on the back, almost a brushed finish because the are stamped, not cast. I was hoping the tumbler would remove those scratches. Am I out of my mind with hope? I cleaned the tumbler first following the directions. I did check every couple hours and the water was clean. I used 2 lbs of shot with only 6 charms (they are thin and about 1 inch or shorter). I used 1/2 teaspoon of palmolive (didn't have dawn). My silver and gold both came out with a blackish color (tarnished looking) and not shiny. Needless to say the scratch marks were still there. I tumbled for about 7 hours. I then spent 15 minutes trying to polish them with a sunshine cloth and they still don't look that good. What am I doing wrong???? I need to get those "brush marks out and have shiny charms. They are as I mentioned sterling silver and gold filled. Please help!! I am going crazy with these things.
While tumble polishing can do wonders for many things, removing those fine lines on flat metal seems to not be one of them. I use a buffing wheel on my flexshaft or polishing machine and different rouges to smooth away fine lines. Or, you can also use different grits of fine sandpaper.
3M makes special sanding papers for non-ferrous metals such as gold and silver up to super fine 6000 grit. They are called, 3M WetorDry®Tri-M-Ite® Polishing papers. You can use those to buff away the marks. I love Sunshine clothes, but they do not contain an abrasive to buff tiny scratches out. Rather they just shine things up by removing surface oxides.
I've found that when putting numerous flat items in a tumbler such as discs, they have a tendency to stick together and rub or scratch a cirle pattern on each other. So, I polish them the old fashioned way, by hand.(sigh) Also, one pound of stainless steel shot is the recommended amount for a 3-pound tumbler.
Both gold-filled and Sterling will tumble beautifully. If you've got a Harbor Freight tumbler, the rubber barrel could be your culprit as to the black discoloration you're getting. Also, remember, the dish washing liquid acts as an agent that holds all the yucky stuff (impurities etc...) that the stainless steel shot removes from the metal. When there are more impurities being removed than the dish soap can handle, it will happily re-deposit itself back onto the metal...hence, the greyish, dirty looking metal. You just need to tumble a bit longer with fresh solution. When your water is thick and black...time to change it! (before that actually) Sometimes when the items are really oxidized, they need to be taken out, re-buffed with the steel wool or 3M scrubby pad and then put into a fresh solution. Other times, you just need to change the solution. I know it sounds like a pain, but eventually you learn what needs to be done by looking at it.