Ink tack is the ratio of how much the ink likes to stick to itself over how much it likes to stick to something else. With rare exceptions, we all want a low-tack ink irrespective of type or color. To facilitate transfer of inks with a higher tack level, the fill-rate of the mesh should be maximized and the flexion of the blade should be optimized to fit the mesh and apply sufficient shear-stress to the ink. 

Full article here from Joe Clarke and Printwear Magazine