Taught my self carbon printing starting in 1992, from an article in ViewCamera Magazine (Nov/Dec 1990 issue). This was after 15 years of silver gelatin printing (16x20 from 4x5). I approached carbon printing from a viewpoint of silver printing -- carbon are sort of silver prints on steroids (at least the way I make them.)
One of the things I like about carbon printing is its almost straight line reproduction of the negative...which means I can photograph in very high contrast situations (such as sunlight penetrating deep into the Redwoods) and still capture that light with compresing the tones. The raised relief gives a nice depth to the images also.
When my triplets were born, I taught myself to make platinum/palladium prints in order to save a little time, as I was a bit busy at home (my wife went back to full time work son after we brought the boys home). I grew to like the slightly soft, in-the-paper look...very different than my previous work.
So now I do both processes. I enjoy making the hand-made print and it has become part of my imagery...a case of both image and process influencing each other.