Not every tile is suitable. Only glazed-surface wall tiles are suitable for photo-quality engraving. The best visual result comes from the gloss white version — the black-and-white contrast shows best on it.
For practice, any broken or discarded glazed tile is perfect — it doesn't need to be white, just glazed.
You paint the tile with some (non-white) base color, then the laser engraves the paint down to the white glaze layer. You engrave white — a negative image.
Sensitive to water, needs a subsequent lacquer treatment.
White paint spray (with TiO2 pigment) onto the tile, then the laser fuses the TiO2 onto the glaze. Physically it's material addition, not removal.
Durable, water-resistant, stays installable.
Titanium dioxide (TiO2) is a white pigment that paint manufacturers use at 5–20% ratios. The laser's concentrated heat converts it into rutile-anatase crystals, which bond physically to the glaze surface.
Wipe the tile with a mildly alcohol-based wipe. Not with soapy or dish-soap water! — the acrylic comes off in bubbles from that.
Spray on a matte, off-white, ivory, or beige spray paint — one layer, using right-to-left then up-down passes. It doesn't need heavy coverage.
Check from a side angle: if it covers the surface everywhere (evenly glossy), it's perfect. It can be engraved right after drying — or even weeks later.
Engrave the positive image (not negative) — you burn the black. Under the laser beam, the TiO2 particles fuse onto the glaze.
Storage: you can spray 4-5 tiles at once. After drying, put a paper towel between them — stored this way, they won't scratch.
Rutile formation is optimal within a narrow speed-power range. "Darkest" isn't always best — excessive black takes away contrast.
Scanning offset: at high engraving speeds, the return-pass lines shift slightly (due to the laser beam's propagation delay). In LightBurn this can be corrected with the Scanning Offset Adjustment setting — especially noticeable at 254+ DPI.
TiO2 particle size is 0.01–0.04 mm — this limits the useful resolution.
Dither only — grayscale isn't suitable, since only black and white (unengraved area) can be produced. In grayscale mode the TiO2 doesn't bond reliably.
The image needs to be high-resolution, detailed, and noise-free — every flaw in the original photo shows up in the finished engraving. Precise mechanics and correct focus are prerequisites.