Digital BW, The Print

Question regarding minor issue with 2200 using K4 inks.

I am printing some photographs with quarter inch black borders.  I
notice that only on the border areas, I am getting some very subtle
dark banding. This has nothing to do with nozzles or head alignment. 
Solid areas within the individual photographs are fine....only
noticeable on a photoshop layer of solid black fill.

My assumption here is that on the layer that is a solid color..that I
should put some sort of noise into that layer...just enough noise to
make a dither...but not enough to take away from the density.

Suggestions on what kind of noise...and how much so that this minor
variation goes away????  

By the way, I am using Innova F Type.  On Matte or Lustre with some
texture...this is not noticeable.

So, for all you experts...what is the best kind of Photoshop noise
that would make a solid black print that way...but hide the minor dark
banding.

Thanks in advance.

Phil