Most black and white images we receive are not true black and white images but are desaturated colour RGB images that still retain some RGB information.
There will always be some variance in colour reproduction because of this. Black and white ‘colour’ is somewhat in the eye of the beholder (or the calibration of your monitor!)
Back in the heyday of Silver Halide black and white production the paper manufacturers produced paper that had warm or cold tones, including various contrast characteristics and post treatments that sent the print from very warm to very cold. When you watched the rolls of prints coming off the printer you will see black and white prints scattered through the batch and most times these are very different from each other
To get the best printing result, please follow the process below before submitting your images
1. Convert RGB image to Greyscale image - this removes all colour information
2. Assign the DOT grain profile