​Mopping the floors and allowing them to dry is a regular practice. This routine is the main cause of dirt accumulating in the small micropores and ridges of the tiles, which results in the tile darkening over time. Dust particles are also mopped into the grout lines, causing them to darken as well. This process occurs gradually and often goes unnoticed for months or even years.

Observing the colour of the floor near baseboards and in closets/pantries will reveal the original colour.