Calima is the fine Saharan dust that regularly reaches the Canary Islands. On outdoor floors it doesn't just sit on top: it works its way into the pores.
The usual mistake
Thinking the floor is old when it's actually full of embedded calima. Many terraces that look worn out recover their colour after a technical clean.
How to spot it
An orange-grey tone that doesn't go away with mopping, darker joints, and a floor that looks dirty again soon after every episode.
Why a hose isn't enough
The particles are microscopic and lodged in the pores. They need a product that releases them and pressure with enough flow to carry them out. Sealing afterwards helps the floor shed the next episode.