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Home › Blog › blog feldspar india aalok overseas › Mesh · Micron · Millimetre Complete Conversion Chart & Guide By Aalok Overseas India
Posted by Admin on April, 15, 2026
Mesh · Micron · Millimetre
Complete Conversion Chart & Guide
Everything you need to specify, order, and verify feldspar & quartz powder grades — mesh-to-micron tables, sieve testing methods, laser diffraction explained, and how particle size impacts ceramic, glass, and paint performance.
Published by Aalok Overseas / FeldsparIndia.com · Rajasthan & Gujarat, India · Mine-Source Exporter
Understanding Mesh Numbers
What Does "Mesh" Mean in Mineral Powders?
Mesh number = the number of openings per linear inch in a woven wire sieve screen. A 200 mesh sieve has 200 wires per inch in both directions — creating 200 × 200 = 40,000 square openings per square inch. The higher the mesh number, the finer the powder.
The relationship between mesh number and opening size (in microns or mm) is inverse and non-linear — it depends on the wire diameter used, which varies by standard (US, Tyler, BSS). The formula is approximate: Microns ≈ 15,000 ÷ Mesh Number (rough guide only).
Mesh → Microns: µm ≈ 14,900 ÷ Mesh No. | Microns → mm: mm = µm ÷ 1000
Example: 200 Mesh ≈ 74 µm = 0.074 mm · 325 Mesh ≈ 44 µm = 0.044 mm
Standard tile body grade
Ceramic glaze / fine grade
Master Conversion Chart
Mesh · Micron (µm) · Millimetre (mm) — Full Conversion Table
Based on US Standard (ASTM E11) sieve series. Tyler mesh equivalents shown where different. Wire diameter varies by mesh — opening sizes are nominal. For specification purposes, always confirm with laser diffraction D90 values.
| US Mesh # | Tyler Mesh | Opening µm | Opening mm | ASTM Sieve | Feldspar / Quartz Grade | Typical Application |
|---|---|---|---|---|---|---|
| 4 | 4 | 4,750 | 4.750 | No. 4 | — | Run-of-mine lump screen |
| 8 | 8 | 2,360 | 2.360 | No. 8 | Lump / Granule | Primary crusher output |
| 10 | 9 | 2,000 | 2.000 | No. 10 | Granule grade | Frit furnace charge input |
| 18 | 16 | 1,000 | 1.000 | No. 18 | Coarse chips | Ball mill feed, ceramic body |
| 35 | 32 | 500 | 0.500 | No. 35 | Medium chips / gravel | Construction aggregate |
| 60 | 60 | 250 | 0.250 | No. 60 | Sand grade feldspar | Sand blasting, foundry |
| 80 | 80 | 177 | 0.177 | No. 80 | 80M Feldspar / Quartz | Pre-ground feed, glass batch |
| 100 | 100 | 149 | 0.149 | No. 100 | 100M Feldspar / Quartz | Coarse ceramic body |
| 120 | 115 | 125 | 0.125 | No. 120 | Coarse feldspar powder | General ceramics body |
| 200 ★ | 200 | 74 | 0.074 | No. 200 | 200M Feldspar ★ STANDARD | Tile body — most-ordered grade |
| 230 | 250 | 63 | 0.063 | No. 230 | Fine feldspar powder | Stoneware body, engobe |
| 325 ★ | 325 | 44 | 0.044 | No. 325 | 325M Feldspar ★ GLAZE GRADE | Ceramic glaze, sanitaryware |
| 400 | 400 | 37 | 0.037 | No. 400 | 400M Feldspar / Quartz | Porcelain, fine china, frits |
| 500 | 500 | 25 | 0.025 | No. 500 | 500M Feldspar / Quartz | Cosmetics filler, specialty coatings |
| 625 | — | 20 | 0.020 | — | Micronized quartz | Paints, rubber, electronics |
| 1250 | — | 10 | 0.010 | — | Ultra-fine micronized | Technical ceramics, semiconductors |
★ Most commonly ordered grades. US Standard = ASTM E11. Tyler mesh openings vary slightly from US Standard for fine meshes. Always cross-check with laser diffraction D90 for specification purposes.
Visual Size Scale
Size in Context — From Visible Grains to Invisible Powder
20–100 mm
Lump / Chips
Visible to naked eye · Can hold in hand
0.177 mm (177 µm)
80 Mesh
Fine sand visible · feels gritty
0.074 mm (74 µm)
200 Mesh
Like flour · slightly gritty feel
0.044 mm (44 µm)
325 Mesh
Like fine talcum · barely perceptible
0.010–0.025 mm
500–1250 Mesh
Micronized · completely silky
Feldspar & Quartz Grade Reference
Mesh Grade → Application Matrix for Feldspar & Quartz
| Grade / Mesh | Size (µm · mm) | Potash Feldspar Use | Soda Feldspar Use | Quartz / Silica Use |
|---|---|---|---|---|
| Lump (20–100mm) | 20,000–100,000 µm | Frit furnace charge | Glass melt batch | Silica glass raw material |
| 80 Mesh | 177 µm · 0.177 mm | Coarse body mix | Rough glass batch | Foundry sand |
| 100 Mesh | 149 µm · 0.149 mm | Standard tile body | Tile / floor body | Glass batch, ceramics |
| 200 Mesh ★ | 74 µm · 0.074 mm | Tile body · wall tile · floor tile · vitrified tile body · stoneware | Tile body · sanitaryware body | Glass batch · paints · adhesives |
| 325 Mesh ★ | 44 µm · 0.044 mm | Ceramic glaze · frit input · bone china body | Glaze · fine porcelain · sanitaryware glaze | Premium glass · specialty coatings · epoxy |
| 400 Mesh | 37 µm · 0.037 mm | Fine porcelain body · frits | Fine china · enamel | High-purity glass · photovoltaic |
| 500 Mesh | 25 µm · 0.025 mm | Cosmetic filler · specialty rubber | Cosmetics · high-end coatings | Electronics · semiconductor |
| 1250 Mesh (D50 ~5µm) | ~10 µm · 0.010 mm | Technical ceramics · nano-filler | Ultra-fine specialty | Semiconductor-grade SiO₂ |
Section — Particle Size Testing
How Mesh Size Is Measured — Methods, Machines & Standards
Particle size verification is critical in mineral trading. A manufacturer specifying "200 Mesh Feldspar" needs confidence that >95% of particles pass through a 74 µm sieve. Here are the four main methods used by Indian feldspar and quartz producers and quality labs:
🔲 Sieve Analysis (Mechanical Sieve Shaker / Test Sieve Stack)
Most common · ASTM E11 / ISO 3310-1 · Used for 20 Mesh to 400 Mesh
How it works: A weighed sample of powder (~100g) is placed on top of a stack of wire-mesh sieves arranged from coarsest (top) to finest (bottom), with a collecting pan at the base. The stack is placed on an electromagnetic or mechanical sieve shaker and vibrated for a set duration (typically 10–20 minutes). Particles smaller than each sieve opening pass through; oversized particles are retained. Each fraction is weighed and expressed as a percentage of the total sample.
Result reported as: "% retained on 200 mesh" or "% passing 200 mesh." Industry standard for feldspar: >95% passing through the declared mesh size. For a 200M feldspar: ≥95% should pass 74 µm sieve.
EQUIPMENT USED
🔧 Ro-Tap Sieve Shaker — US standard; combined tapping + circular motion
🔧 Electromagnetic Sieve Shaker — Low vibration for fine powders; reduced blinding
🔧 Air Jet Sieve — Single sieve with upward air jet; ideal for cohesive powders >20 µm
🔧 Wet Sieve Washer — Water-assisted for sticky or agglomerated powders
📐 Test Sieves: Stainless steel woven wire cloth; ASTM E11 / ISO 3310-1 certified; diameters: 200mm, 300mm standard
💡 Laser Diffraction (Laser Particle Size Analyser)
Gold standard for fine powders · ISO 13320 · Gives D10, D50, D90 · Used for 325M and finer
How it works: A laser beam is directed through a dispersed sample (wet or dry dispersion). Particles diffract the laser light at angles inversely related to their size — large particles diffract at small angles, small particles at large angles. A detector array captures the scattered light pattern, and software (using Mie or Fraunhofer theory) calculates the full particle size distribution.
D-values explained: D10 = 10% of particles are smaller than this size · D50 (median) = 50% of particles are smaller · D90 = 90% of particles are smaller. For a 325M feldspar: D90 ≤ 44 µm.
D10: ~8–12 µm · D50: ~20–28 µm · D90: ≤44 µm · D100 (max): 50–52 µm
INSTRUMENTS
Malvern Mastersizer 3000 — Industry standard; range 0.01–3500 µm
Beckman Coulter LS 13 320 — Polarization Intensity Differential Scattering
CILAS 1190 — Widely used in ceramic QC labs
Sympatec HELOS — Dry dispersion; high throughput
Standard: ISO 13320 · ASTM B822
🌀 Air Classification & Settling Methods
Used in production milling · Andreasen Pipette · Elutriator · Air Classifier
Air Jet Classifier: Used inline in feldspar milling circuits. Powdered feldspar enters a rotating air stream; centrifugal force separates coarse particles (thrown outward, recycled to mill) from fine particles (carried through to product). The classifier wheel speed determines the cut point (e.g., 44 µm for 325M product). This is how continuous 325M production is maintained at volume.
Andreasen Pipette / Sedimentation: Particles suspended in liquid settle at rates governed by Stokes' Law (settling velocity ∝ particle diameter²). Samples withdrawn at timed intervals and weighed. Slower, but useful reference for QC labs without laser instruments. Suitable for 5–100 µm range.
KEY MACHINES
Alpine Classifiers — Hosokawa Alpine; standard in Indian feldspar mills
Netzsch Ecutec Classifier — Precise cut points for 325M–500M
Andreasen Pipette Kit — Lab method; ISO 13317-1
Elutriators — Vertical air-column separation; older technology
🔬 Optical & Electron Microscopy (SEM / OM)
Visual confirmation · Shape analysis · Used for research & dispute resolution
Optical Microscopy (OM): Useful for particles above ~5 µm. A sample is dispersed on a glass slide, observed under a calibrated optical microscope, and individual particles measured manually or via image analysis software. Quick visual check; less suited for statistical size distribution.
Scanning Electron Microscopy (SEM): For very fine powders (<20 µm) or morphology verification. An electron beam scans the powder surface; secondary electron emission creates a high-magnification image. Used to verify particle shape (angular vs. rounded), surface texture, and agglomeration. Common in quality audits for 500M–1250M micronized feldspar and quartz. Not used for bulk sizing.
OM INSTRUMENTS
Olympus CX23 · Zeiss Axiolab · Leica DM500 + image analysis software (ImageJ, LAS)
SEM INSTRUMENTS
JEOL JSM-6390 · Hitachi TM3030 · FEI Quanta · Tescan Vega — used in NABL/SGS certified labs
Quick Reference
Method Comparison — Which Test for Which Grade?
| Method | Best For | Mesh Range | Speed | Output | Standard |
|---|---|---|---|---|---|
| Sieve Analysis | 80–400 Mesh; routine QC | 20M – 400M | Fast (15–20 min) | % pass / % retained | ASTM E11 · ISO 3310 |
| Laser Diffraction | 325M and finer; full PSD | 325M – 1250M+ | Very fast (2–5 min) | D10, D50, D90, PSD curve | ISO 13320 · ASTM B822 |
| Air Classifier | Production control; inline | 200M – 1250M | Continuous | Cut-point separation | Internal mill standard |
| Sedimentation | Sub-sieve fine powders | 325M – 1250M | Slow (hours) | Cumulative size distribution | ISO 13317 · BS 3406 |
| SEM / Microscopy | Shape, morphology, disputes | All fine grades | Slow (sample prep) | Visual + measurement | ISO 9276 · ASTM E2809 |
Our Products
Feldspar & Quartz by Grade — Sourced, Milled & Exported from India
Every mesh grade below is XRF-verified, laser diffraction tested (D50/D90 certified), packed in 25 kg HDPE bags or 1 MT jumbo bags, and exported from Mundra / JNPT / Kandla to 50+ countries. AIFTA Form AI and SAFTA Certificates of Origin available for all ASEAN and SAARC destinations.
Potash Feldspar
KAlSi₃O₈ · K₂O 12–14% · Fe₂O₃ <0.10% · Rajasthan origin
Uses: Tile body · Ceramic body · Floor & wall tiles · Vitrified tile · Stoneware · Glass batch · Frit input
View Product →Soda Feldspar (Albite)
NaAlSi₃O₈ · Na₂O 9–11% · Fe₂O₃ <0.08% · Gujarat / Rajasthan origin
Uses: Ceramic glaze · Sanitaryware · Fine porcelain · Glass & frit · Tiles · Bone china · Enamel coatings
View Product →Quartz Powder / Silica
SiO₂ ≥99.0–99.5% · Fe₂O₃ <0.02% · Rajasthan / AP origin
Uses: Glass manufacturing · Paints & coatings · Adhesives · Epoxy flooring · Rubber filler · Photovoltaic glass · Semiconductor SiO₂
View Product →⭐ Why Buyers in 50+ Countries Choose Aalok Overseas / FeldsparIndia.com
✅ XRF-Verified Every Batch
Full oxide CoA: SiO₂, Al₂O₃, K₂O, Na₂O, Fe₂O₃, TiO₂, CaO, LOI — from NABL-accredited labs
✅ Laser PSD Certified
D50/D90 values reported on CoA for all 325M and finer grades — Malvern Mastersizer certified
✅ AIFTA / SAFTA / GSP CoO
Full preferential trade documentation for Vietnam, Indonesia, Bangladesh, Sri Lanka, Nepal
✅ Free Samples in 48 hrs
500g–2kg samples with full CoA dispatched worldwide to qualified industrial buyers
✅ Mine-Source Supply
Direct from Rajasthan & Gujarat mines — no intermediaries, consistent quality and pricing
✅ SGS / BV Option
Third-party pre-shipment inspection by SGS or Bureau Veritas arranged on request
Get in Touch
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