A. Possibly a large quantity of adhesive must have been used (thickness over 2cm). It is of the most importance that the adhesive does not exceed the thickness of the tile. If we have height differences on the substrat, we smooth it out with tiles’ adhesive before placing the tiles (for small differences) or cement mortar for smooth concrete.

B.The “teeth” of the spatula spreading the adhesive are thin and deep set and as a result, the gap they leave after spreading tends to be covered by the adhesive (since it tends to expand in order to fill the substrat surface of the tile in a uniform way). In this case, we use a spatula with smaller gaps between the teeth and without a big depth.

C.Sometimes, we notice a “sinking” of the tiles’ corners when they form a “joint cross”. Usually, this is due to the “arching” that some tiles have (of a secondary quality) and not to the technician’s poor workmanship.