Park is a real plus, but even more important is the proper surface texture. I use 120 grit Aluminum Oxide at 100psi+.
Many times the original park has been applied over a surface texture too smooth for Cerakote.
No need for stainless steel park tank. An enameled stew pot from Wal-Mart works just fine. I do it outside, over a single burner Coleman cook stove.
Blast, then hang using stainless steel wire. Degrease using carb or brake cleaner. Park using the Manganese Phosphate from Owens Group/Palmetto Industries of Taylors, SC.
Parts are removed from the park pot and placed into another pot containing hot water and some degreaser. like 'Purple Power' or '409'. Then a hot water rinse until the water runs clear with no suds.
Dry with compressed air before water spots develop.
Then hang using black iron wire and alligator clips.
This next part is IMPORTANT!
Degrease again using a highly volatile solvent. My preferred liver killer is the brake cleaner from Wal-Mart. Dry using a heat gun or a hair dryer before water spots can develop.
Compressed air from your shop compressor contains oil and other contaminents.
I use a Paasche VL double-action air brush with the medium needle and nozzle.
I prefer the parts be at ambient temperature.
Use just enough air pressure to get the Cerakote on the work without 'sputtering'.
Do the hard to reach areas first. When doing the exterior surfaces, put on enough Cerakote to achieve a 'wet' look, just shy of running. This takes practice! And good light. And I use 2X reading glasses.
Let the parts air cure for 30 minutes or so.
As for curing, a toaster oven won't cut it. Beware of proximity to the heating elements. Use an infra-red temperature gun to determine surface temp in your particular oven. I like to preheat the oven to 300f, add the parts and then 'ramp-up' to 250f over an hour or so.
After curing you can use #000 steel wool to give the Cerakote a 'finished' look. Use caution here. Use a small, tightly wound ball and target small specific areas. Careful on the edges.
I do not have a dedicated coating area. I spend a fair amount of time setting up, tearing down and cleaning everything. The whole process takes me most of a day.