Which Screen Should i use?

Hi,
Which ink and what fabric and colour are you printing on?
Kenneth

they are red shirts with white plastisol ink

Hi BP,
Not sure where you are from so I will list cm and inch thread counts. Typically, for the flash coat, we would use a gold or yellow 43T(110T), the gold or yellow mesh, reduces the undercut of light refraction when exposing the screen, hopefully you have a single source exposure lamp, and for the top coat, a 62T(160T), even a 51T(130T). If it is a small run, we would run the flash around twice, drying it in between.
K

I would use a 160 or 180 mesh.

A little bit of curable reducer will help get the ink through
the mesh.

If you print/flash/print you won't have an issue with opacity.