Expandable Graphite Powder
An intercalated flake-graphite compound — also called intumescent or exfoliating graphite — engineered to unfold into a low-density thermal barrier the instant it is heated. Specified by carbon content and expansion rate for fire safety, sealing and advanced-materials work.
Find the Right Expandable Graphite Grade
Tell us your target carbon content, expansion rate and mesh size. We’ll recommend the best grade, provide a competitive quote and include the corresponding Technical Data Sheet (TDS).
Think of it as graphite with a spring coiled inside every flake: chemically quiet at room temperature, then explosively voluminous under heat.
Typical properties
Representative values — confirmed per batch on the TDS
Specifications by grade
Select on carbon content, expansion rate and particle size
Expandable graphite is not a single product but a family of grades. Higher carbon and coarser flake give bigger, cleaner worms for foil and gaskets; finer, lower-carbon grades give a controlled, uniform expansion suited to coatings and cost-driven metallurgical use. Representative tested lots:
| Grade | Carbon | Ash | Volatile | Expansion | Onset | Particle size | pH |
|---|---|---|---|---|---|---|---|
| EG-92 | 92.37% | 7.63% | — | 250 ml/g | 190–200 °C | +100 mesh (82%) | 5.67 |
| EG-91 | 91.23% | 5.9% | 2.87% | 230 ml/g | — | +100 mesh (70%) | 6.1 |
| EG-90 fine | 90.36% | 9.64% | — | 38–49 cm³/g | — | 270 mesh (92%) | 5.4 |
| EG-84 | 83.86% | 16.14% | — | 56 cm³/g | — | −200 mesh (76%) | 6.6 |
| EG-83 | 83.33% | 13.85% | 2.82% | 58 (@750 °C) | — | −200 mesh (74%) | 6.8 |
Mesh-defined grades (50 / 80 / 100 / 140, ≥93% carbon, 200 cm³/g @600 °C, onset 220 °C) are also available. Every figure is verified on the batch Technical Data Sheet.
Where it is used
One material, many industries
The defining use: halogen-free intumescent additive in coatings, fire-stop seals, pillows, boards and cable wraps. On heating it swells to choke flame and seal openings.
Feedstock for flexible graphite foil and sheet used in gaskets and packings for valves, flanges and pumps — reliable across wide temperature and chemical ranges.
Melt-cover and protective-slag / heating agents in steelmaking and casting.
Conformance and lost-circulation additive in oil recovery; component in thermal-management and battery-related materials.
Raw material for carbon brushes, graphite parts and conductive, self-lubricating components.
Packaging, storage & safety
Supplied as an odourless black powder in 25 kg bags palletised inside 1 MT bulk bags, with custom packing on request. Store sealed in a cool, dry place; the material can cake if exposed to moisture, so keep bags closed until use. It is non-toxic in normal handling and not classified as hazardous for transport under IMO/IMDG — simply minimise airborne dust. Full detail is in the Safety Data Sheet below.
Datasheets & downloads
Full tested values, grade by grade
PDFTDS — EG-91 (230 ml/g)High-carbon grade
PDFTDS — EG-83 (58 @750 °C)Economy grade
PDFTDS — Grade 30-270N270-mesh fine grade
PDFTDS — Grade 3538Standard −200 mesh
PDFTDS — Mesh 50/80/100/140Particle-size grades, ≥93% C
SDSSafety Data SheetCAS 7782-42-5 · full 17 sections
Characteristics
What sets expandable graphite apart from ordinary flake
Expandable graphite begins life as high-purity natural flake graphite. During manufacture the flake is passed through an intercalation stage, where reactive species — usually an acid system — are chemically inserted between the parallel graphene sheets that make up the graphite crystal. The result is a stable intercalation compound: the outward flake still shows a silvery, plate-like morphology, yet it now stores latent chemical energy between its layers.
Apply heat quickly and that stored energy is released. The intercalant flashes to gas, and the pressure between the graphene planes overcomes the weak van der Waals bonds holding them together. The layers are driven apart along the c-axis and the particle stretches into an accordion-like “worm” many times its original length — turning a dense black powder into a lightweight, heat-blocking, non-combustible mass. Because nothing burns in the process, the expanded network is an excellent passive fire barrier as well as a thermal and acoustic insulator.
How the expansion works
Three stages from flake to worm
IntercalationAcid molecules are locked between the graphene layers, forming a dormant, room-temperature-stable compound.
TriggerRapid heating past the onset temperature (≈190–220 °C) vaporises the intercalant and builds high inter-layer pressure.
ExfoliationThe layers spring apart along the c-axis; each particle unfolds into a worm and bulk volume grows up to several hundredfold.
Common questions
Is expandable graphite the same as expanded graphite?
They are two stages of the same material. Expandable graphite is the intercalated powder before heating; expanded (or exfoliated) graphite is what you get after it has been heated and unfolded into worms. You buy the expandable form and expand it in your own process.
Why is it used as a fire retardant?
When flame heats the coating, the graphite exfoliates into a thick, insulating char layer that blocks heat and oxygen from the surface below. It is halogen-free and low-smoke, which is why it is favoured over many traditional flame retardants.
What determines the expansion rate?
The intercalation chemistry, flake size and carbon purity. Coarser, higher-carbon flake expands more (up to ~250 cm³/g); finer flake expands less but more uniformly. Choose the grade that matches your target volume.
What is low-sulphur expandable graphite for?
Standard grades use a sulphuric-acid intercalant that leaves trace sulphur. For sealing against stainless steel or for electronics, low- and ultra-low-sulphur grades reduce the risk of corrosion and outgassing.
How should it be stored?
In its original sealed bag, in a cool dry place. It can absorb moisture and cake, which affects flow, so keep it closed until use.
Match a grade to your process
Send us your target carbon, expansion rate and mesh — we will recommend a grade, quote it and share the batch datasheet.