Ceramic (stoneware / technical terracotta)

Physical properties

Laser processing

Ablation generates fine mineral particulate (silicates, aluminosilicates) with potential crystalline silica if the ceramic contains quartz. Direct extraction and ventilation mandatory.

CO₂: CO₂ laser engraving on unglazed white/light ceramic produces a matte mark by surface ablation. Contrast is modest but sufficient for plaques and personalisation. Typical power 60–80% on 40–80 W machines, reduced speed. On glazed ceramic the laser removes the glaze revealing the bisque underneath, with stronger contrast. Cutting is impossible without waterjet or diamond disc cutting.

Diode: Very limited application. Blue diodes perform poorly on white surfaces and common ceramic. Marking possible on dark ceramic or with absorbent coating (e.g. Cermark).

Fiber: Fibre laser with ceramic marking compound (e.g. Cermark, Enduramark) enables permanent black high-definition marks on glazed ceramic. Preferred method for professional marking on giftware and objects.

CNC / milling processing

Milling of unfired ceramic (greenware/bisque not yet fired) is feasible with carbide bits at low speed: the material is brittle and porous, chipping is the main risk. Fired ceramic (bisque, stoneware) requires diamond tooling with continuous water cooling exclusively. Not workable with standard wood CNC routers. Wet CNC with a suitable spindle is the most common method for engraving stoneware tiles.

Post-processing

Sanding: Sanding with wet silicon carbide paper, grit 80 to 400. Fired tiles are sanded with wet diamond pads. Do not use alumina abrasives on hard ceramic (excessive abrasive wear). Always work wet to suppress particulate.

Primer: Unglazed ceramic (bisque) is porous and absorbs paints directly. Traditional ceramic glazing does not require primer. For acrylic paints on fired ceramic, a coat of universal primer improves adhesion.

Gluing: Two-component epoxy for structural bonding. For ceramic object repairs: Araldite Rapid or Loctite Power Epoxy. Neutral silicone is adequate for non-structural applications. The surface must be clean, degreased and dry.

Over time: Fired ceramic is extremely durable (millennia under normal conditions). Porcelain stoneware is resistant to acids and chemical agents. Unfired bisque is fragile and moisture-sensitive. Glazing protects the surface from absorption and scratches.

Common defects

• Chipping and micro-fractures during mechanical cutting or drilling — especially at corners
• Dimensional shrinkage during firing (5–12% depending on the clay body) — must be factored in for precise-dimension parts
• Poor laser engraving contrast on unglazed white ceramic without a marking agent

Safety

Recommended PPE: mask_ffp2, eye_protection, gloves_work

Ceramic dust (especially raw/greenware) contains silica and aluminosilicates. Crystalline silica risk is significant in dry mechanical processing. FFP2/FFP3 mask mandatory for dry processing. Always prefer wet processing. Safety glasses for chips during cutting.

Availability and formats

Commercial formats: tiles 10×10 – 60×60cm, bisque plates and bowls, alumina rods and bars, flexible ceramic sheet (fibre ceramic)

Related materials

Sources

• ISO 13006 — Piastrelle ceramiche — Definizioni, classificazione e caratteristiche
• EN 14411 — Ceramic tiles — Definitions, classification, characteristics and marking
• Epilog Laser — Engraving on Ceramic and Tile Application Guide