Twitter progress, page-236

it is indeed confusing, minus means "smaller size than" and plus means "larger size than" I prefer microns more straightforward and not confusing, this link explains it :

http://www.espimetals.com/index.php.../stainless-steel/334-understanding-mesh-sizes

If you needed a powder that was closer to size you would need to specify two mesh sizes. For example: Tantalum Powder, -40+100 Mesh, 3N8 Purity This powder would have particles that were smaller than 40 mesh (420 micron) but larger than 100 Mesh (149 micron).


or this one :

https://hollandaptblog.com/2014/03/...-i-know-which-sanitary-screen-gasket-to-pick/

So what is mesh and how is it determined? It’s pretty easy, actually. Simply count how many openings there are in one inch of screen. The number of openings is the mesh size. So a 120 mesh screen has 120 openings per linear inch. A 250 mesh screen will have 250 openings per linear inch.

or this one :

https://www.industrialspec.com/resources/mesh-and-micron-sizes/

MESH AND MICRON SIZES

What is a micron?
Micron is the measure of length most frequently used to describe tiny particle size. The term micron is actually a commonly used shorthand for micrometer (American spelling) or micrometre (international spelling). The official symbol for micrometer is μm, sometimes simplified as um. A micrometre is defined as one-millionth of a meter, a little more than one twenty-five thousandth of an inch.

What does mesh size mean?
Mesh size is the mesh number (a US measurement standard) and its relationship to the size of the openings in the mesh and thus the size of particles that can pass through these openings. Figuring out the mesh number is simple. All you do is count the number of openings in one linear inch of screen. This count is the mesh number. A 4 mesh screen means there are four little square openings across one inch of screen. A 100 mesh screen has 100 openings per inch, and so on.



Hope that helped,