Mesh Count
40
Openings per linear inch
Sifting Solutions
40 mesh corresponds to a nominal opening of 400 microns (0.400 mm). In botanical screening, this is generally treated as a medium separation step for dry sift, pollen, and powder handling lines.
Mesh Count
40
Openings per linear inch
Opening
400 microns
0.400 mm
Opening Inch
0.01575
Nominal clear opening
Open Area
39.7%
Wire diameter 0.235 mm
| Mesh count | 40 |
|---|---|
| Nominal opening (micron) | 400 microns |
| Nominal opening (millimeter) | 0.400 mm |
| Nominal opening (inch) | 0.01575 in |
| Nominal wire diameter | 0.235 mm |
| Nominal open area | 39.7% |
A 40 mesh screen is built with 40 openings per linear inch. For this reference, the clear opening is listed at 400 microns, with a nominal wire diameter of 0.235 mm and an open area near 39.7%. These values are used for engineering comparison, not as a substitute for final supplier drawings.
At 400 microns, this screen size tends to support stable dry separation while still moving material efficiently across the deck. In production terms, it sits in the medium part of the screening range and is usually selected after operators define the target fraction, feed dryness, and deck loading rate.
These formulas explain the unit relationship shown in the table.
Micron from mm
micron = mm x 1000
0.400 mm x 1000 = 400 microns
mm from micron
mm = micron / 1000
400 / 1000 = 0.400 mm
Inch conversion
inch = micron / 25400
400 / 25400 = 0.01575 in
Process notes are assembled directly from the selected opening value so each page stays consistent with the table above.
When a 40 mesh screen is used for pollen collection, the nominal opening is 400 microns. This is usually chosen early in the process to clear large botanical fragments before a finer finishing screen is introduced.
For dry sift separation, 40 mesh gives a nominal clear opening of 400 microns. This range suits balanced production lines that need separation accuracy without sacrificing deck productivity.
In powder grading work, 40 mesh is roughly equivalent to 400 microns. In powder grading, this opening is suited to separating coarse granules from a broader botanical grind.
For botanical pre-screening, a 40 mesh cloth opens at about 400 microns. The screen can still be used as a controlled pre-screen when the incoming material already has a reasonably narrow particle spread.
38 mesh at 425 microns will pass a coarser cut and hold higher throughput. 45 mesh at 355 microns will shift the cut point finer and tighten material control.
Nominal opening values were curated from commonly referenced industrial wire cloth and U.S. sieve conversion charts. Actual clear opening can vary by weave style, wire diameter, and manufacturing tolerance.
Nominal opening values may vary slightly by weave and wire diameter. For purchase approval, always confirm the actual cloth specification issued by the manufacturer.