Fine Wet on Wet Base is a transparent base used in process color printing.  It gives the ink a short body that prints very well wet-on-wet and helps prevent dot smearing and dot gain by allowing the ink to penetrate further into the fabric.  
 It is not designed to reduce the viscosity of the ink.  It is a balanced additive and will not affect the cure of the ink.   It will greatly reduce the opacity of any ink it is added to.