The most important thing in any bluing process is the metal prep IMO.
This. It's all in the preparation. You can express blue it but this process will take several days. After polishing and degreasing, you apply the rusting solution and let it hand in a sweat cabinet (box/pvc with a can of water and a light bulb) for a day. Remove it and card it off, degrease, apply another coat of rust solution and back into the box. Repeat until desired blued is attained.