I've never forced a patina. Certainly as others said cutting the right thing is helpful. Hot protein has pretty much guaranteed blue for me. The brightest colors come in the very early stages of patina formation. After a while the color fades.Is the only way to get color like this forcing the patina? every time i look at this thread all the colors are so vibrant and all my patinas are very light or leaning slightly more towards dark blue/brown. or is this more to do with the steel/heat treat and such
Another big factor is the finish of the knife. In my experience the more polished the steel is, the more intense the patina.