I was struggling with the restricted mediums I have at my disposal at work, usually just black and red markers. I have been dabbling in coloured pencil, and I have a selection of alcohol based coloured markers, but I took them home. So I found myself wanting a method of bridging the stark gap between white and black, to add a little gradation, and ultimately soften the image and allow subtle shading.
I purchased two grey Copic markers (warm grey 2 & 5 I think). They work ok.. It's plenty good enough for some signs at JB. Once I get used to shading and covering larger areas neatly, I think they will turn out OK.