Intended for outdoor use as memorials and landscaping markers, unglazed ceramic tile, also known as quarry tile, is a popular item. While it can be masked and painted, that is usually not a good or permanent option, especially for use in the elements.
Unglazed ceramic tiles can, in fact, be marked with a conventional raster job using a CO2 laser. It is, however, time-consuming, requiring low speed and high power to make a decent mark. By using the same technique for color-filling with inside vector hairlines when marking metals, unglazed ceramic tile can also be marked with a vector job. It saves a lot of time compared with a conventional raster job and produces a much better mark.
Firing the laser onto the tile creates a kind of black glass mark. Depending on your settings, you can achieve indented or raised marks. The raised marks come with slower speeds. The high heat generated causes the material to bubble up.
Tile composition can vary, affecting the results. It’s a good idea to test the material first. The underside is a good place to dial in your settings. When done right, you’ll have a well-defined permanent mark suitable for outdoor applications.
—Jim Puentes, COOLaserCraft