I am finding it impossible to print halfones finer than 30dpi as the dark shadow areas will go black after a few prints, using a 110 T mesh and medium squeegee. could problem be with the ink? I am using Speedball Acrylic, am waiting for some solvent based 4colour process black to try, any clues woudl be appreciated..
What you are experiencing is called dot gain and it can be caused by one or more of a wide range of issues, including but not limited to:
-Screen mesh too loose
-Squeegee too dull
-Flood to heavy
-stencil too thin
-mesh too coarse
-ink too thin
-too much lift (or, on a clamshell semi-auto, too much peel)
-uneven squeegee pressure
It can be frustrating as fuck, but is a fact of screenprinting tones, particularly on textiles.
Aside from the above problems and more others may name, the best way to correct it is to anticipate it in creating your halftones.
All of the above it true. If you want to print finer than 30 lpi then you should print with a finer screen. 110 is only suitable for dots around 25 lpi. Some of your problems are dot gain but I would guess that you are having a lot of ink offset onto the back of your screen in the non-image areas. I also find a harder squeegee prints htones better.
Interesting, good point about creating halftones I have lightened up shadow areas before I put the half tone on with some success in the past..by lift do you mean what I would call 'snap' gap between mesh/screen and paper/bed?
My technique isn't quite as consistent as it should be regarding pressure, angle, flood etc. but I get a pretty decent half tone using 230 mesh. The dot gain tells me when to tighten up the technique but not so much that I should stop and rethink how I'm doing it altogether.