Could someone tell me the definition of a screen's mesh? I am working on a
project that calls for #4 mesh screen. The local hardware has some screen
but it is unmarked and neither of us knows how to measure it.
I like #8 (1/8") screen, myself. Not quite too fine to not work well (like
window screen, for instance).
"I've got more trophies than Wayne Gretsky and the Pope combined!"
- Homer Simpson
#4 mesh screen is nominally 1/4" square [4/in.]
The opening dimension is determined by the size of the wire it's made
Brass screens for soil testing are made from 1-1/2" opening to 200
mesh. You can get the ASTM specifications from most any civil
On the other hand, ordinary 1/4" rabbit wire from the local hardware
store may be all you need.
Some people have crossed references here so I had to butt in:
4 mesh is not the same as 1/4" screen. 4 mesh is 4 full openings per
inch as measured between parallel wires, perpendicular to the wire
faces, center to center of wires. 1/4" opening is a CLEAR opening as
measured the same way except ignoring the wire.
On each, the gauge of the wire should be specified also. For example, a
1/4" opening fabricated from 14 gauge wire (.080") would actually be a
(nominal) 3 mesh.
It gets a little anal but you do have to measure between PARALLEL wires,
perpendicular to the wire face. Some meshes are parallelograms rather
than square so instead of measuring along the length or width relative
to the edges of the screen, you do need to specify wire to wire.
The "perpendicular to parallel wires" thing doesn't come up much in
hardware cloth type screens but becomes true all the time in chain link
material (like fencing). In case you haven't noticed, chain link fence
is NOT the same as when we oldsters were kids. One of the first cheats
was to change from 6 mesh to 2" opening. Back in the days when chain
link wire was a little heavier, this made some manufacturers appear
cheaper as the opening was just a fraction larger so there was less
material, fewer overall spirals to make on a large run, and fewer loops
in each spiral. Of course chain link fencing is now made with HUGE
openings and tiny wire to make it cheap as dirt.
It also comes up on security fencing where the openings are to be quite
small. You can't get a finger in 1/2" mesh but you might be able to in
Koz (who rambled to kill a little time)
You made it way too complicated. 4-mesh means four wires per inch, PERIOD.
If you want 1/4" openings, you specify 1/4" SPACE CLOTH.
There certainly are other things that can complicate it, like different wire
sizes, predominance of metal vs. openings in fine meshes, etc.
But simply said, if the spec calls out "Mesh size", it means "wires per
inch". If it calls out OPENING size, you can do the math, or just order