What he is referencing - as I understand - is the receptive nature of all emulsions to being directly printed on.
Some emulsions the ink will wick like crazy going all over the place - others the ink will stay right where it dropped - think water proof Vs. non waterproof etc.. inkjet film.
Within the wet ink direct to screen machines/families - the different inks used all have different results when hitting the screen. I personally saw more "dot gain" when we switched to t6 then with D2a. I needed to recalibrate my machine. The actual difference was up to 4%.
I initially said you were right, and you still are, but there is more to that. As described in that book I wrote about it, the RZ value or what Danny was referring to is not just the emulsion "type" and characteristics, but also the way it's coated and dried or
not dried. Ideally, there should be at least enough emulsion on each mesh type to provide a smooth surface. Ideally, the costing technique for a high mesh should not be the same for the lower mesh. You are looking for minimum of 10% and a max of 25% EOM and also looking for consistency as well. With that, comes a good RZ value.
Not everyone does this and a roughness,
doesn't make it less durable. It just helps in other areas like forming a good gasket between garment and stencil. A good smooth surface also makes for a more visually appealing imaging onto the stencil from a DTS. I say visually appealing since a lesser quality stencil does little actual affect to the image quality of dots. Your stencils smoothness does not cause satellite dots or "scatter dots".
The impact of any wet ink in DTS on a screen for sim process at a typical lpi (55-65) on a typical high mesh (305)...is of little concern. Does it have any slight impact. I'd say yes, a minuscule affect. The surface would have to be extreme (and there are some out there), maybe 10% of all shops I had visited I'd guess were extreme. The more common affects is so little it's negative affects to wet ink are not visible to the naked eye and certainly not visible in wash out or print.
Smoother is better but not a requirement to burn good screens. I'd say medium to good is desired. You can burn screens and print jobs with very rough thinly coated screens (know as poor screen quality) where the mesh threads show up like waffle patterns...and still run an order. (I would not), but many do and just not as good. Like running your DTS at it's fastest settings for production. For typical jobs, (bold lettering), run it at it's fasted speed. You can still do 55lpi at fastest settings, but it's not as good as running is a bit slower for your finer detailed jobs.
Changing a DTS ink type can affect the gain, thus needing to adjust your curves in your RIP. A mechanical Re-calibration of the device actually does nothing to improve gain on the stencil. The difference will be a result of the chemical makeup of the ink or, (the thickness) of said ink.
