I have found that Muriatic Acid (dilute hydrochloric acid)  will totally remove the bright chromate plating from modern fasteners.  It is very fast & easily washes off with water.      This is available at most hardware stores & is used to clean concrete & as a drain cleaner.   
  
It is best to submerge the parts in the acid until the fizzing stops.   The same acid will clean hundreds of fasteners if you keep it in a jar with a lid.   
 
 Eye protection, rubber gloves & good ventilation  are a must.   
 
Heavily plated items will leave a dark residue which comes off with a wire wheel easily prior to painting.
		 
		
		
		
		
		
		
		
		
	
	 |