I use the steam tower method. I went to stove pipe, as I was doing enough volume the heavy wall PVC began to sag.
I set the stovepipe in about an inch of water, , hang the barrel from a wood cap with a wire hook. and put all on a gas burner. You need to keep the heat up for 20 minutes with this method, vs. 25 minutes for boiling. The steam is hotter than the boiling water, accounting for the time difference. I drop the screws, bolts, etc. into the boiling pot.
This can affect your finished color. I doubt you can get the desired results with pouring water over it and letting it sit. Not enough direct heat for a long enough time period.
As was mentioned, don't let it oxidize long. I just want to see a light haze on the steel, no red rust. Six cycles seems to be pretty average.
