The foundation of how you determine a decent LPI remains the same no matter how you change up the numbers or introduce the variables.
Mesh opening, Mesh diameter, # of threads per inch, all give you something to work with. I illustrate the results of using different numbers. Find yours.
When you introduce a different variable such as thin thread and open area you get a slightly different result, but the method is still the same. You just fine tune what "your" number is. At least with this guide, new people might look away from just throwing up a 65lpi on a 150 mesh.
Whether you use 3.75, 4, 4.5, or 5 doesn't matter. This isn't a rule. It's a procedure guide geared towards those new to screen printing. To get one to a better result not intended to confirm a particular usage.
If someone uses thin thread and takes a 330 mesh and divides by 4 to get 82.5lpi and rounds off to 80lpi and successfully captures the 3% dot then that's fantastic! All the better. But if you are not using 80lpi on that 330, then the idea is the same as described in my example. For example, if you are using the 330 mesh yet only printing 65lpi, then that is the same concept of my using the example of taking a 305 mesh and using 5...and only using 55lpi. Using 5 as a procedure only aids in assuring you do capture that 3% dot without difficulty.
If new to the industry (as we have read many times) you might toss out any random lpi that we commonly see used such as (55-65) and use that even tho you are using a 110-200 mesh. This gives people a starting point.
