The flat surface of the plate or stone is slightly roughened , or etched , and divided into hydrophilic ( = water-loving ) regions that accept a film of water and repel the greasy ink , and hydrophobic regions which repel water and accept ink .
The flat surface of the plate or stone is slightly roughened , or etched , and divided into hydrophilic regions that accept a film of water and thereby repel the greasy ink , and hydrophobic regions that repel water and accept ink because the surface tension is higher on the greasier image area which remains dry .