New Kompac metering rolls are surfaced on a precision high speed lathe which leaves a fine uniform surface with a ‘tooth’ that provides a surface grip that holds a consistent ink film ‘thickness’.
As a metering roll ages, its surface becomes filled with ink pigment, varnish, and wears smooth from rubbing and it’s machined surface becomes increasingly smoother and shiney reducing the surface grip that is ‘very’ necessary for carrying a uniform ink film.
When your metering roll becomes ‘too smooth’, its’ surface cannot hold ink, causing ink to emulsify on the form roll which in turn causes ink banding accross the sheets.
If the metering roll does not have serious surface ‘defects’, or groove wear at roll joint to ceramic end-rings, the Delrin surface can be re-surfaced and re-energized by a light wet-sanding with #400 sand paper in the rollers direction of rotation.
I recommend installing metering roll in a lathe off-press to perform this re-surfacing using Varn’s V-120 as a wetting/deglazing solution.