I "soaked" all my hardware in carb cleaner first. Then washed them off with the soapy and rinse water from the clothes washer. After drying for a couple of days, a weeks worth of tumbling in a rock tumbler with the metal filings from a brake shop. A quick dip in kerosene which rinses most of the brake metal dust and gives the hardware a protective coat to prevent rust and you are ready - almost. Let the hardware "dry" for a week or two. Now it's bead blasting time. For ease in handling in the blasting cabinet, use metal shower curtain clip rings for nuts, washers and other small items with a hole, to mount for bead blasting. I use metal plumbers tape to mount 1/4 and 5/16 inch screws and bolts, larger I do by hand. TP Tools and Equipment
http://www.tptools.com/ has special containers for small screws, or if there are just a few to do, use a medium size alligator clip. All the techniques I use minimize handling by doing them in bulk.
That the method I use to prepare hardware for phosphating. I do the same for zinc plating I send out. It ain't cheap, but the results are worth the expense.
I'm pretty sure I ruined them by getting them too cleaned and polished.
What "polishing" do you do?
Jim