Granite
Frequently asked questions
Can Granite be laser cut?
No: Granite is not suitable for laser cutting. Adequate extraction/ventilation is required.
Can Granite be CNC machined?
With some limitations: Granite can be CNC machined.
Is Granite food safe?
Yes, Granite is food safe even in its raw state.
Physical properties
| Density | 2600.0–2800.0 kg/m³ |
|---|---|
| Tensile strength | 14.0 MPa |
| Thermal expansion | 8.0 µm/m·K |
| Moisture absorption | Negligible |
Laser processing
Laser ablation of granite generates crystalline silica (quartz) particulate and aluminosilicates. Crystalline silica is a Category 1A carcinogen by inhalation. Forced ventilation and direct extraction on the workpiece are mandatory, not optional.
CO₂: CO2 engraving possible on dark granites (absolute black, black impala): the laser melts and ablates feldspar and quartz crystals, generating a white-gray mark with good contrast. On light granites contrast is poor. High power required: 60–100% on 60–80W machines, low speed. Cutting is impossible with CO2 laser in maker contexts.
Diode: Not applicable on light granites. On very dark granites a light surface marking is possible at high power.
Fiber: Fiber laser marking used industrially for dark granite plaques. Not typical in maker contexts.
CNC / milling processing
Mechanical machining of granite possible only with diamond tools on a rigid high-power gantry CNC with continuous water cooling. Granite is extremely hard and abrasive (Mohs 6–7): it wears carbide tools in seconds. Not feasible with standard CNC routers.
Post-processing
Sanding: Sanding with diamond grinding wheels, wet, progressing from coarse grit (50) to fine (400). Mirror polishing requires diamond resin polishing pads and is performed exclusively wet with an orbital polisher. Polished granite is nearly impervious.
Primer: Polished granite is nearly impervious and does not require sealing in standard applications. A water-repellent impregnator is recommended only for flamed or bush-hammered (porous) surfaces in high-traffic environments.
Gluing: Bondable with two-component epoxy adhesives or neutral silicone specific for natural stone. The surface must be dry and clean. Granite does not absorb adhesive like porous materials: mechanical fastening (bolts or dowels) is preferable for structural joints.
Over time: Virtually unlimited durability. Granite is the natural stone most resistant to abrasion, acids, and weathering. Unlike marble, it is not acid-sensitive. UV exposure does not degrade it. Resistant to frost and thaw cycles. The only form of natural degradation is oxidation of pyrite inclusions (yellow-rust spots on granites with metallic inclusions).
Common defects
- Edge chipping during mechanical cutting or waterjet due to the crystalline structure
- Yellow-rust oxidation stains on granites with pyrite inclusions in the presence of prolonged moisture
- Insufficient laser engraving contrast on light granites (grey, beige) — prefer slate or black granite
Safety
Recommended PPE: mask_ffp3, eye_protection_goggles, gloves_work
⚠️ HAZARD: Granite dust contains free crystalline silica (quartz) in significant percentages (20–30%). Inhaling granite dust poses a serious risk of silicosis and lung cancer. FFP3 mask mandatory for any dry mechanical processing. Always work wet. Sealed goggles and work gloves.
Availability and formats
Commercial formats: tiles 30×30 and 60×60cm, polished or flamed slabs 20–60mm, coasters and chopping boards, kitchen countertops 20–30mm
Related materials
Sources
- EN 1342 — Lastre di pietra naturale per pavimentazione esterna
- UNI EN 1469 — Prodotti di pietra naturale — Lastre per rivestimento
- IARC Monograph 68 — Silica, Some Silicates, Coal Dust and para-Aramid Fibrils
Information on compatibility, processing parameters and safety is purely indicative. MakerSpecs accepts no liability for damage to persons or property arising from the use of this data. Always check the safety rules and the manufacturer's official manuals before carrying out any processing.