thanks; never tried that; i only wrapped coil directly on mesh; hadn't even occured to me to even try to put the rolled mesh in afterwards!
btw, wouldn't it be easier to wrap a mircocoil anyway; I'm looking at that picture and wondering why the wraps are so widely spaced; is that deliberate, or just easier to wrap that way?
It sort of depends on the design of the atty; the taller the minimum center post height is the more wraps your going to have if you go the micro coil route, or you end up with really long +/- legs trying to get the coil at the center of the vertical wick.
My current 3/4 open wrap (2 strand twisted 28ga) around a 3/32" SS cable with 500 mesh sleeve nails 0.50 +/-0.01 ohms every time, the same quantity of wire would need to be wound on a 14ga needle to be tall enough on my genny with its fixed + post height. Then the thing would leak like a sieve.
If I wanted to run such a thin wick, I'd have to modify the wick hole, easy enough with a pressed in insert, but I don't want to go that route.
Similarly I could reduce the + post height and do a short micro coil, still the open coil works fine, so why expend money and energy that isn't needed?
Most genesis atties are built with the lower gauge resistance wires or ribbon, or multiple strand twisted higher gauge resistance wires. Both are fairly easy to pre-coil, in fact I have a batch of them that were not only pre-coiled but also installed then removed prior to use. This makes re-coiling a 30 second job at best.
With the multitude of wick options out there; SS mesh (and the many methods of using it), SS mesh plus other wick material, cotton, yarn, ceramic, cable, the list goes on, the genny is versatile. A single genny can be built into hundreds of formats to suit the users desires.
You ask "wouldn't it be easier to wrap a mircocoil anyway?", well that's not the attraction of a genny. Easier is the world of clearomizers, where the genny is at the opposite end of the spectrum with unlimited possibility.
The original question about cotton or mesh can be answered with a multitude of options, cotton can be wicked through the deck or just to the deck, normal cotton wick rules apply (less is usually the right amount but not always), mesh can be made into a hollow straw, a filled with cotton straw or super tight visually solid roll, it can be cut with the grain or across the grain, it comes in a number of mesh sizes which can be combined together in a single wick, it can extend just into the deck, or through the deck, in some gennies it can be curved to form a U wick.
As you can see the number of options are nearly unlimited. Each method has qualities that are liked or disliked, I'm liking the SS cable and 500 mesh sleeve wick at the moment because it is just working day in and day out with no real maintenance, you just don't have to break down good stainless steel stuff all that often.
I'd suggest doing the cotton wick trimmed to the deck surface if you don't have a ton of experience doing other builds. You'll be replacing the little bit of cotton regularly, so you'll have plenty of time to learn to roll the various mesh wicks.
Solid mesh is easy to make once you figure it out (roll loosely by hand, work it with care to get it as tight as you can, flame oxidize it, lay the wick between two pieces of card stock and roll the wick tighter) then test fit to a very uniform coil that was pre-wound on a rod then mounted in the genny. It's a good idea to keep notes on what size your initial wick mesh was cut to so you can adjust it later. Any way trim excess if you need to and re-burn it because you just exposed fresh metal.
Hollow straw type mesh wicks are just that, they will wick faster the more open you build them, really really fast. Fast enough to challenge your coil building ability and put your battery into the Ok I'm really working hard to keep up realm. You will know exactly when it's time to change a battery or seriously adjust your VV/VW settings, because you will get a mouthful of warmed up
juice and little vapor if they aren't where they need to be.
Cotton, I would suggest getting a really pointy set of tweezers to make this easier; make a regular cotton wick to fit the coil (an extra copy off to the side is nice to check if you have the right amount of cotton), insert the wick pointy end through the coil, grab the cotton and pull it through and over the deck side and cut off the tightly rolled section, then pull the wick back just enough so that the cut end is flush over the wick hole (no more), now trim the top of the wick and prime it with your favorite
juice. This works with an open fill hole, flow rate depends on how close your cotton wick is to the wick hole, the closer the wick matches the hole size the better off you'll be, bigger is fine, smaller not so much.
Cotton II, you can run the wick into the
juice tank, good luck with that. I looks goofy, and really doesn't work that well.
Maurice
is that I like my KF (with cotton) just fine, but most of the e-liquids I buy are more flavorful in a mesh-wicked genny. 
. It wasn't hard for me at all to install a perfect coil, but MAN was it hard to get them glowing evenly, the negative post would always pull the coil towards it now matter how much I braced it. But I figured it out and now I have awesome results with a 45degree (diagonal) coil evenly spaced between the two posts.
