Marble restoration—grinding, honing, polishing, sealing—requires specialized equipment, stone-specific knowledge, and dust-controlled processes. The wrong contractor etches, unevenly grinds, or seals in stains. Here's how to vet for competence.
1. Technical Expertise Verification
- Stone identification: Must distinguish marble, limestone, travertine, onyx, terrazzo, engineered quartz — each demands different grit sequence, chemistry, pressure.
- Damage assessment: Maps etch depth, scratch pattern, lippage, stain type, moisture — not "looks dull."
- Process articulation: Explains metal→hybrid→resin progression; wet vs. dry; powder finale; sealer type (impregnating vs. topical).
- Certifications: INSTALL/NTCA (USA), TTA (UK), Stone Federation — not general tiling certs.
2. Equipment Portfolio (Must Own, Not Rent)
- Planetary machines: Klindex, Lavina, HTC, Werkmaster, Klüger — 17–32", 3-phase, 10–30 HP.
- Diamond tooling inventory: Full grit range (30–11,000) in metal, hybrid, resin, electroplated; Frankfurt/Fickert/Velcro backs.
- Dust containment: HEPA vacuum + water feed = zero airborne silica (OSHA/WHS compliance).
- Edge/corner tools: Hand grinders with shroud + vacuum; triangle/teardrop pads.
- Moisture testing: Tramex/CME — verifies slab dry before sealing.
3. Project Transparency & Documentation
- Written scope: Area, stone type, current condition, grit sequence, sealer spec, cure time, warranty.
- Before/after photography: Standardized lighting; raking light for scratch/etch verification.
- Sample area: 1–2 sq ft test panel — approve finish before full project.
- Daily logs: Grits used, water volume, dwell times, issues encountered.
4. Quality & Accountability Markers
- Insurance: $2M+ general liability; workers' comp; stone-specific rider.
- Warranty: 1–2 years workmanship; sealer per manufacturer (1–5 yrs).
- References: 3+ similar stone + damage level; 1+ year old for durability proof.
- Pricing model: Per sq ft (not hourly) — includes protection, cleanup, sealing.
5. Red Flags
- "We use a buffer and some powder" — no planetary, no grit progression.
- "Sealer makes it shiny" — topical acrylic = yellowing, peeling, trap stains.
- No dust control — "we clean up after."
- Cash only; no contract; no business license.
- Subcontracts the work — "my guy does it."
Cost Benchmarks (2024, Major Markets)
- Cleaning + light polish: $3–$6/sq ft
- Hone + polish: $8–$15/sq ft
- Full restoration (grind→hone→polish→seal): $15–$30/sq ft
- Terrazzo: +20–30% (harder matrix)
- Stain poulticing: $50–$150/spot additional
Marble restoration is a surgical procedure on stone. The contractor's hands, tools, and integrity determine whether the surface lives or dies. Vet like you'd vet a surgeon.
