For starters, plastisol inks tend to be much thicker than water-based inks, which means you’re going to need a screen with a bigger opening to get the ink through to your T-shirt.
The most commonly used mesh sizes for plastisol are 110 and 156. 110 mesh will give you a relatively thick deposit of ink (plastisol, of course) and are great for printing a white underbase, for example.
With water-based inks, you’re going to need a higher mesh count due to the consistency of the ink itself. If you’re working with plastisol inks and you print with a 230 mesh screen, you’re not going to get much ink to lay down, which would be fine if you’re going for a transparent look, but generally, it’s not recommended due to potential coverage and opacity issues.
Likewise, if you’re printing water-based ink on 156 mesh, you’re probably going to get too much ink down on the shirt, and as it dries it can start to bleed, and you lose the sharpness of your artwork. Every job is unique, but in terms of water-based versus plastisol, a good rule of thumb to follow is thick ink, lower mesh count; thinner ink, higher mesh count.
—Texsource Screenprinting Supply