I am assuming that the banding you are experiencing is primarily in the
highlights. The key here is to:
a) tweak the compensation curve to match your particular paper/coating
method/developer combination
and
b) get the exposure of the digital negative correct. You may think "but
they're just black dots", but this is not true. The negative acts like a
hybrid analog/digital negative and it is important that the density of
the negative be correct in order to mate correctly with the
characteristic curve of your paper.
Because you are trying to match a an irregular curve moving a little in one
direction or antother along the curve will create a mismatch, and hence
banding.
To help you visualize this, consider a graph of the characteristic curve
of your paper. Next, cut a piece of cardboard to match this curve. Mark the
10% point on the cardboard curve. Now move align the point you just
marked with the 15% point on the graph -- this represents making a
digital negative too dense (for a correctly exposed negative the 10% mark
of both the cardboard and the graphe would line up). With the 10% and
15% marks aligned you will note a curve mismatch -- you won't be able to
get both curves to match along their entire lengths. The points where
the two curves diverge can lead to banding.
c) Banding can sometimes be caused by the type of line screen used --
round dot, for exapmple has banding near 50%, elliptical dot in other
areas. The differently shaped dots were all developed to help this
problem. There are even some special linescreen patterns which change
shape depending on the density.
d) Print so that your 1% dot prints paper white. Do not have any 0% dot
areas in your negative.
e) In my image file I make the very lightest, non-pure-white tone have at
least a 7% density (this is before the platinum compensation curve is
applied).
Good luck!
David