I just used new bolts in the metals of my choice ,I looked into refurbishing hardware ,but unless its a restoration,just use matching new hardware for less time and hassle............
I used stainless and yellow zinc coated soo far ......I was able to use which ever head style I wanted in almost any material wanted.
If I were to do any restorations of nuts and bolts at home ,I would use the vibratory polisher and apply a plating such as uses electricity to bond the plating to the fastener ,rather than a spray can of coating.