I'm using my memory so I can be wrong. From approximately the beginning of XX century until half 30s, FS coaches were painted in green, from there to the 60s Castano and Isabella (two tones of brown ) were used, then a little time of sole Castano and then the slate grey era until the 80s, when started three liveries at the same time : liver red for long distance stock, concrete grey, orange and violet for local services and red and orange for medium distance stock. From 90s a new unified livery of white with blue and green stripes has been in use and now there are new liveries beginning to be applied.
All the above mentioned is valid only for FS, private railroads had their proper colours, and also inside FS there have been various special liveries (treno azzurro, TEE etc. ).
About black smoke, surely it was for the photographers benefit. In my little experience black smoke appears when coal begins to be burnt or when the grill is dirty and fire cannot breathe.
Ciao
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