Smudged tiles
Wall with ventilation grid

 
Tiles with a perfect smooth texture quickly appear smudged by dust, rain and weathering, which requires occasional cleaning. So, to reduce maintenance, the tiles shown here are quasi pre-smudged and the pattern is baked in, which disguises a certain amount of further smudging.

 
 
 
 
Another part of this wall is shown in Counting tiles (Photos 2021-1).