Ok, for poly foam front trucker caps or similar material that needs the tenacity of later of hot melted glue to adhere the ink we powder the sheets wet, flicking the back with two fingers gelling in the dryer. These do look something like sugared donuts and do not result in a halo though you must ensure you get the excess powder off.
Private labels- T-120 (could be wrong on the number) paper for multi color, just about anything else for single color. For labels, we need a little extra tenacity but not the amount described above. Mix some powder into the ink. You don't need a ton and nowhere near so much that it gets pasty. In fact, the adhesive isn't totally necessary for Ts, we've just found it to be a little extra insurance and lets you apply that batch to different fabrics. Just use less if printing it is an issue. We do print through the lowest mesh count our greatest open area that can hold the detail, good point on mesh clogging.
350-360° for 10-12 sec, 'medium' pressure for labels. Time and temp needs to be reduced sometimes on long runs that heat up the platen. 400 @5 sec sounds nice but I imagine you get more pronounced marks on the shirt from the press?