Digital BW, The Print

Some weeks ago, I picked up an Epson C86 and the MIS Ultratone EZN inks 
to fool around with black and white output. I'm following Paul Roark's 
recommended workflow at:

http://home1.gte.net/res09aij/C86-EZ-UT-Readme.htm

Specifically, I'm printing onto EEM with the C86 driver set to "best 
photo," with high-speed mode off.

Last night I printed an image with a snowfield and some sky. Both are 
fairly broad areas with all the pixels nearly the same tone; snowfield 
very light, sky about middle gray. I'm getting horizontal banding in the 
printout. It is clearly visible by eye, though it is small. The banding 
is more easily seen in the sky, but is definitely present in the snow as 
well. The bands are about 0.75mm apart and are about equally thick. The 
file is 320 dpi. On a casual glance, most people I show the print to do 
not notice the banding.

I ran a nozzle check (everything OK), and a head alignment check 
(everything OK). I printed the image again after this, just in case, 
with the same results.

I then downloaded and installed QTR and printed the image at the same 
size on my 2200, just to see if somehow this was inherent to the image 
and I couldn't see it on the screen. The banding does not appear in that 
print.

The C86 banding gives the impression of being the result of a bad dither 
pattern - perhaps the result of a buggy dither algorithm?

Does anyone have any recommendations on how to proceed? I'm not seeing 
this on other images I've printed with the C86, but none of the other 
images have such broad areas of a single tonality. I've wondered whether 
the output file resolution is causing problems, and I might run that 
through a spline to increase the resolution and see what happens. But I 
thought I'd check here first. Thanks!

--
Jeff Medkeff
Eagle River, Alaska