Mesh Sizes and Microns
 What does mesh
size mean? Figuring
out mesh sizes is simple. All
you do is count the number of openings in one inch of screen (in
the United States, anyway.) The
number of openings is the mesh size.
So a 4 mesh screen means there are four little squares
across one linear inch of screen.
A 100 mesh screen has 100 openings, and so on.
Note, therefore that as the number describing the mesh size
increases, the size of the particles decreases.
Higher numbers = finer powder.
Mesh size is not a precise measurement of particle size.
Screens can be made with different thicknesses of wire.
The thicker the wires, the smaller the particle passing
through that screen, and vice versa.
|
What is a micron? A
micron is another measurement we use for measuring particle size. A micron is one-millionth of a meter or one twenty-five
thousandth of an inch.
What do the minus ( - ) and plus ( + ) plus signs mean when
describing mesh sizes? Here’s
a simple example of how they work.
–200 mesh aluminum would mean that all particles will
pass through a 200 mesh screen. A +200 mesh aluminum means that all the particles are
retained on a 200 mesh screen.
How fine do screens get?
That depends on the wire thickness.
But the supplier of our screens does not offer any screens
finer than 500 mesh. If
you think about it, the finer the weave, the closer the wires get
together, eventually leaving no space between them at all.
So, beyond 325-400 mesh, we usually describe particle size
in “microns.”
|
|
|
This
table is adapted from a post made by Ken Kosanke to the
PML and
previously published in a PGII Bulletin.
|
| U.S.
Standard * |
Space
between wires
|
|
| Sieve
Mesh No. |
Inches |
Microns** |
Typical
material
|
|
| 14 |
0.056 |
1400 |
|
| 28 |
0.028 |
700 |
Beach
sand |
| 60 |
0.0098 |
250 |
Fine
sand |
| 100 |
0.0059 |
150 |
|
| 200 |
0.0030 |
74 |
Portland
cement |
| 325 |
0.0017 |
44 |
Silt |
| 400 |
0.0015 |
37 |
Plant
pollen |
| (1200) |
0.0005 |
12 |
Red
blood cell |
| (2400) |
0.0002 |
6 |
|
| (4800) |
0.0001 |
2 |
Cigarette
smoke |
| *
The mesh numbers in parentheses are too small to exist as
actual screen sizes; they are estimated and included just
for reference. |
MESH
TO MICRON CONVERSION CHART
|
US MESH
|
INCHES
|
MICRONS
|
MILLIMETERS
|
|
3
|
0.2650
|
6730
|
6.730
|
|
4
|
0.1870
|
4760
|
4.760
|
|
5
|
0.1570
|
4000
|
4.000
|
|
6
|
0.1320
|
3360
|
3.360
|
|
7
|
0.1110
|
2830
|
2.830
|
|
8
|
0.0937
|
2380
|
2.380
|
|
10
|
0.0787
|
2000
|
2.000
|
|
12
|
0.0661
|
1680
|
1.680
|
|
14
|
0.0555
|
1410
|
1.410
|
|
16
|
0.0469
|
1190
|
1.190
|
|
18
|
0.0394
|
1000
|
1.000
|
|
20
|
0.0331
|
841
|
0.841
|
|
25
|
0.0280
|
707
|
0.707
|
|
30
|
0.0232
|
595
|
0.595
|
|
35
|
0.0197
|
500
|
0.500
|
|
40
|
0.0165
|
400
|
0.400
|
|
45
|
0.0138
|
354
|
0.354
|
|
50
|
0.0117
|
297
|
0.297
|
|
60
|
0.0098
|
250
|
0.250
|
|
70
|
0.0083
|
210
|
0.210
|
|
80
|
0.0070
|
177
|
0.177
|
|
100
|
0.0059
|
149
|
0.149
|
|
120
|
0.0049
|
125
|
0.125
|
|
140
|
0.0041
|
105
|
0.105
|
|
170
|
0.0035
|
88
|
0.088
|
|
200
|
0.0029
|
74
|
0.074
|
|
230
|
0.0024
|
63
|
0.063
|
|
270
|
0.0021
|
53
|
0.053
|
|
325
|
0.0017
|
44
|
0.044
|
|
400
|
0.0015
|
37
|
0.037
|
|
