Phosphating comes with 2 options, Zinc and Manganese, both of these produce varying levels of gray to almost black (depending on the concentrate, age of bath, length of time in solution, and base material). The biggest difference between the two is level of porosity at the microstructure level and depth of color. Automotive hardware is generally Zinc while many Guns use manganese. Zinc also makes a good base for painted surfaces or can be oiled (sealed) for a nice grey finish. As an alternative to oil I use a water soluble sealer available from Caswell plating. The sealer can be left natural for a beautiful zinc finish or painted over at a later date.
Phosphating will require stainless steel or porcelain pot, bowl . . . , needs to be heated to approx 180-200 and you'll need to season the bath prior to first use (1 time only as long as you continue to use a portion of your previously seasoned bath for future jobs). This is easily accomplished with iron filings, or shavings and a coffee filter.
Phosphating can be accomplished by the average home user pretty easily for minimal investment. The process is horribly convenient when doing a restoration and can be easily stored in plastic containers for long periods, making it easy to use at a later date to freshen up details. I tend to refinish even brand new hardware if it doesn't have a good finish.
Hardware prep can vary but in general I blast mine first and will often hit it with a wire wheel to get a nice finish prior to plating. The exception is if I intend to paint it then you may elect to skip the wire polish. I suggest you try the process both ways and make an informed decision what works best for your needs.
Zinc phosphate is not a great corrosion protector and the reason you may receive new parts in a box with corrosion. It's ability to deter corrosion is largely reliant on the oil or sealer placed on the porous surface. Though its outstanding compared to black oxide.
I purchased Zinc phosphate from Brownells (yes, the gun company). Remember your buying concentrate, the pint bottle will make gallons of parkerizing Zinc phosphate solution.
http://www.brownells.com/gunsmith-tools-...g-prod1106.aspxI don't recommend performing the process in your home, a garage is the better location, buy an old stove or electric portable burner.
