I have found that the paper outut, even with coated paper is unacceptable.
The ink is not dense
enough to provide clean enough copy to accurately print the half tone dots,
even in the diffusion mode.
I found that oiling the paper produced dots that were too mushy to be
useful. The sharpest output was
with transparancy film. But not good enough to produce useable negatives.
What does work however
is making a positive on transparency film and then creating a negative using
Lith film with AB developer.
The dots are sharp enough to reproduce clearly in kalitype using a medium
surface paper.
As to resolution - The 360 dpi produced by the epson on the transparency
film in the dithering modes is
adequate forgum bichromate. Dave Scopick in his book recommends a half tone
range of 85 - 150 lpi. Assuming
2x bpi, 360 is more then adequate. By the way you can optimize the dot or
line pattern by setting the
printer to the no-halftone mode and using Photoshop to generate the pattern.
I have also found that the useable range (as measured by a half tone grey
scale) is about 1.5 but this is
also a function of the quality of the dots. What I do is make a full scale
picture out of the photo I have
scanned in, and then apply one of the curves I have stored to fit it within
the 1.5 OD range automatically
adjusting the characteristics for the process it is to be used with.
I have not yet tested to see if the reproducability is precise enough to
generate seps. for gum which is
really what I would like to accomplish.
Peace
Al