I tried the nitre bleing twice, both were failures, first one was straw colored with bright blue spots causes by air bubbles that I didn't remove, after sanding it all down and starting over, it came out straw colored again, some blue splotches, looked terrible.
I bought a new burner for my grille, but it still isn't long enough to heat the 24½" tank, burner 21½" long, the blueing in the ends just didn't get hot enough, when I reduced the heat to keep the middle at about 600º, the blueing in the ends of the tank cooled off and solidified. I added a propane torch under each end to keep the ends hots, but it was a real circus trying to maintain even heat throughout the tank, which resulted it a terrible finish.
Soooo, to do a barrel, I'll need to make a custom burner that's longer, I also need to get some more KNO3, 10lbs is not quite enough, just too shallow, I added a couple trailer axle stubs to the tank to raise the level a bit which was enough to immerse the barrel if I held the underlug so it was sideways which didn't work out well, the wire hanger just didn't cooperate all the time.
So for now, I'll just do frames, trigger guards, spacers and other smaller parts. FWIW, the two axle stubs came out a deep blue, but not any better than the Belgian blue that I got on the barrel after I sanded it all down for a forth time with 600 grit, and finished it today, except for the round to octagon area which was hard to card and has a slightly redish hue, the barrel came out a beautiful deep, satin black, it took 14-16 cycles of carding and blueing (I lost count!
) to get there, but it's worth it.
Tim