Buying natural flake graphite for the first time — or switching supplier — can be confusing. Grade designations vary between producers, purity figures are reported in different ways, and particle size is described using mesh numbers, micron values, and D50 measurements that don't always map clearly onto each other.
This guide covers everything a procurement manager or engineer needs to understand to specify and purchase natural flake graphite with confidence.
What does Cg% mean — and why it matters
Cg stands for graphitic carbon — expressed as a percentage of total mass. It is the primary quality indicator for natural graphite and tells you how much of the material is actually graphite (as opposed to mineral impurities, moisture and ash).
A grade marked ≥94% Cg means at least 94% of the material by weight is graphitic carbon. The remaining ≤6% consists of mineral ash (silicates, iron oxides etc.) and moisture.
The purity grade ladder
| Grade | Cg% | Typical ash | Main uses |
|---|---|---|---|
| Industrial (SGF-91) | ≥91% | ≤9% | Refractory bricks, foundry applications, carbon brushes |
| Technical (SGF-94) | ≥94% | ≤6% | Lubricants, coatings, EMI shielding, seals, gaskets |
| High Purity (SGF-96) | ≥96% | ≤4% | EDM, brake linings, high-performance lubricants |
| Battery Grade (SGF-98) | ≥98% | ≤2% | Li-ion anode feedstock, advanced composites |
| Ultra Pure (SGF-99) | ≥99% | ≤1% | Battery anodes, graphene precursor, nuclear |
In general, higher purity costs more. But specify the minimum purity your application actually requires — there is no benefit to paying for SGF-99 if your process specification only requires 94% Cg.
Particle size: mesh, microns and D50
Natural flake graphite is sold in a range of particle sizes, described using three overlapping systems:
Mesh size (Tyler or US mesh)
A mesh number refers to the number of openings per inch of a sieve screen. The higher the mesh number, the finer the particles that pass through it. Graphite sold as "+80 mesh" means it is retained on an 80-mesh sieve — i.e., it is coarser than 80 mesh (particles larger than ~180 µm). "+200 mesh" means particles larger than ~75 µm.
| Mesh designation | Approximate particle size | Typical use |
|---|---|---|
| +50 mesh | > 300 µm | Coarse refractory |
| +80 mesh | > 180 µm | Refractory, large-flake battery feedstock |
| +100 mesh | > 150 µm | Refractory, lubricants |
| +150 mesh | > 106 µm | Lubricants, coatings |
| +200 mesh (fine flake) | > 75 µm | Coatings, EMI, battery feedstock |
| −200 mesh (powder) | < 75 µm | Lubricants, pastes, conductive inks |
D50 (median particle diameter)
D50 is the median particle size: 50% of particles by volume are smaller than this value, 50% are larger. It is the most precise way to specify graphite powder and is measured by laser diffraction. When specifying graphite powder for coatings or battery use, always request D50 and D90 values (the 90th percentile particle size).
Flake vs powder: which form do you need?
Flake graphite retains its platelet morphology and large aspect ratio. This is critical for lubrication (the flat structure provides the sliding surface), battery anode feedstock (large flakes yield more spherical particles per tonne in spheroidisation), and certain refractory mixes where the flake structure contributes thermal conductivity.
Graphite powder is produced by milling flake to finer sizes. It has a smaller and more uniform particle size distribution. It is preferred for coatings, pastes, conductive inks, and applications where consistent dispersion matters more than preserving individual flake geometry.
10 questions to ask your graphite supplier
- What is the graphitic carbon content (Cg%), not just fixed carbon?
- What is the particle size — D50, D90, and mesh size?
- What is the ash content and ash composition (particularly Fe, Si, S)?
- What is the moisture content at shipping?
- Can you provide a batch-specific Certificate of Analysis?
- Is the material REACH compliant? Can you provide the SDS?
- What is the country of origin and mine name?
- Is a pre-shipment sample available for qualification?
- What is the minimum order quantity and lead time?
- What are the Incoterms and port of dispatch?
At Graphite.se we provide full answers to all ten questions for every grade of Skaland flake graphite — including batch-specific CoA, REACH documentation, mine certificate of origin and FCA pricing — within one business day of your enquiry.