I really like that you made this a sticky brother GM!
One distinction in the rated size among different screens is an absolute
rating. Here is a link to an article that explains the difference between absolute rating vs. nominal rating for filters:
....so basically which size of particle is allowed to pass through the screen or is left on top of it.
Different mesh material is going to be either multifilament
. Here's an article explaining the distinction:
As the article linked above in this post points out, most of the "silkscreen" and printing cloths you find online and at craft stores is going to be multifilament. It isn't that this multifilament won't work, it is that the monofilament mesh holes will retain there rated size much better and that the filament itself is more durable (the multifilament will fray over time).
Multifilament mesh has a rating with "xx" (example: 10xx) in its rating while monofilament does not
. Monofilament mesh will list the micron or millimeter size of the filament used.
The material of the mesh is polyester (that usually means polyethylene) or nylon. Folks use both for dry sieving. For ice-water resin collection you want polyester monofilament (I learned this last bit from Vorsprung, in this forum) as nylon is hygroscopic and will absorb moisture while the polyester won't.
In above pic is a 12'"x12" and a 24"x12" mesh sheet.
I use a 120μ and a 27μ polyester monofilament mesh sheet for filtering small QWISO (quick-wash isopropyl hash-oil) runs which is better than a coffee filter. Jar of QWISO is poured first through a stainless steel wire mesh colander than through the 120μ and finally through the 27μ mesh.