Glass bead sizes are quoted in mesh (USA and Asia) or microns/millimetres (Europe and technical sheets). Both appear on real purchase orders, so being able to move between them matters – especially for blasting and grinding grades where a one-size mistake changes surface finish completely.
Glass bead size chart: mesh to micron conversion
The table below converts a single mesh number to the standard opening of that screen. Use it when a spec quotes one unit and your mill, blast gun or paint line works in the other.
| Mesh | Sieve opening (µm) | Sieve opening (mm) | Where it typically sits |
|---|---|---|---|
| 10 | 2000 | 2.00 | Very coarse – heavy deburring |
| 12 | 1700 | 1.70 | Very coarse – heavy deburring |
| 14 | 1400 | 1.40 | Coarse – surface preparation |
| 16 | 1180 | 1.18 | Coarse blasting, coarse grinding media |
| 18 | 1000 | 1.00 | Coarse blasting, grinding media |
| 20 | 850 | 0.85 | General blasting, grinding media |
| 25 | 710 | 0.71 | General blasting |
| 30 | 600 | 0.60 | General blasting, finer grinding media |
| 35 | 500 | 0.50 | Medium blasting |
| 40 | 425 | 0.425 | General finishing |
| 45 | 355 | 0.355 | Finishing |
| 50 | 300 | 0.30 | Finishing, light deburring |
| 60 | 250 | 0.25 | Fine finishing |
| 70 | 212 | 0.212 | Fine blasting, paint additives |
| 80 | 180 | 0.18 | Fine blasting, premix compounds |
| 100 | 150 | 0.15 | Fine finishing, coatings |
| 120 | 125 | 0.125 | Fine fillers |
| 140 | 106 | 0.106 | Fine fillers |
| 170 | 90 | 0.090 | Fine fillers, paint additives |
| 200 | 75 | 0.075 | Fine fillers |
| 325 | 45 | 0.045 | Very fine fillers |
Openings follow the standard sieve series (ASTM E11 / ISO 565) and are nominal. They describe one screen, not an average bead: a 20/40 grade sits between two screens, so always read the band, not the single row.
What Linghang supplies: grade bands
Beads are quoted and shipped as a band between two screens, which is what a purchase order actually specifies:
| Mesh | µm (approx.) | mm (approx.) | Typical use |
|---|---|---|---|
| 16-30 | 1180-600 | 1.18-0.60 | Thermoplastic drop-on / coarse grinding |
| 18-40 | 1000-425 | 1.00-0.425 | Road marking, grinding media |
| 20-40 | 850-425 | 0.85-0.425 | Drop-on road marking (typical) |
| 20-30 | 850-600 | 0.85-0.60 | Grinding media |
| 30-80 | 600-180 | 0.60-0.18 | Premix, composites, fine paint |
| 40-70 | 425-212 | 0.425-0.212 | Blasting / finishing |
| 70-140 | 212-106 | 0.212-0.106 | Fine blasting, paint additives |
Mesh, micron and “grit” – what each term means
Mesh counts the openings per linear inch of the screen: 40 mesh means roughly 40 openings per inch, so a higher mesh number is always a finer bead. Micron (µm) is a direct measurement – one micron is one thousandth of a millimetre – and it is the unambiguous way to order, because it does not depend on which mesh standard the other side is using.
“Grit” is the loose trade word for blast-media size, and it is worth being careful with it. Coated abrasives are graded on the bonded-abrasive (CAMF / P-grade) scale, which is not the same as a sieve mesh number. Glass beads are not crushed grit: they are sieved spheres, so the mesh and micron figures above are the ones that apply. If a spec quotes a grit number, confirm which scale is meant before converting.
Why the band matters more than the number
Two batches can both be called “20-40 mesh” yet differ in how much material sits at the coarse vs fine end. Tight particle-size distribution gives steadier retroreflectivity in road markings and more predictable wear in mills. Ask your supplier how the band is screened and whether the batch test is available.
Choosing a size
- Road marking (drop-on): 20-40 or 20-100 mesh depending on paint film and spec.
- Premix/composites: 30-80 mesh is a common choice for even dosing.
- Grinding media: from 0.6 mm to 1.18 mm and up, matched to mill and product.
- Blasting: 40-70 mesh for general finishing, finer for delicate surfaces.
Linghang publishes every grade in both mesh and mm, from 1.18 mm down to fine paint sizes. Browse grinding & blasting beads or all products – tell us your target size in either unit and we will confirm the matching grade. To read the percentages on a batch test rather than the size itself, see how to read a sieve analysis.
Frequently asked questions
How do I convert glass bead mesh size to microns?
Mesh counts the openings per linear inch of the screen, so a higher mesh number means a finer bead. The standard sieve series (ASTM E11 / ISO 565) gives fixed openings: 20 mesh is 850 microns, 40 mesh is 425 microns, 60 mesh is 250 microns, 100 mesh is 150 microns, 140 mesh is 106 microns, 200 mesh is 75 microns and 325 mesh is 45 microns. Use the table in this article for the full 10–325 mesh range.
Why are glass beads sold in mesh bands rather than single mesh numbers?
Because a single screen does not describe a product. A 20/40 grade sits between two screens — it passes the 20 mesh screen and is retained on the 40 mesh screen. That band is what a purchase order actually specifies, and it is why you should always read the range rather than the individual row when comparing quotes.
Is mesh size the same as grit number?
No, and confusing the two causes real specification errors. Mesh numbers come from the sieve scale and describe sieved spheres. Grit numbers for coated abrasives come from the bonded-abrasive (CAMF / P-grade) scale, which is a different system. Glass beads are sieved spheres, not crushed grit, so ask which scale is meant before converting any figure.
What micron size glass beads are used for road marking?
Most road marking beads sit between roughly 1.18 mm (1180 microns) and 125 microns, depending on the standard and whether they are drop-on or premix. Common bands include 20–40 mesh (850–425 microns) for drop-on and 30–80 mesh (600–180 microns) for premix compounds.
Related reading
- Choose Mesh Size — size grading
- Glass Bead Blasting Media — blasting applications
- Sandblasting Mistakes — blasting applications