Digital BW, The Print

For those that are interested, here is a bit of info on Carbon Black 
pigments from a manufacturer of the various types.

http://www.mbssth.com/pigment-black.htm

http://www.mbssth.com/carbon-black1.htm

Note that carbon black is NOT pure carbon like graphite; it has various 
oxygen-containing groups on its surface that considerably affect its 
properties, and which are modified further by ink manufacturers apparently. 
So 'PURE CARBON' is not true of inks based on carbon black.

Bob Frost.