1099LF will lower the viscosity  of opaque, standard opacity and low bleed inks without affecting the bleed resistance or fusing characteristics of the ink being mixed.  This additive is especially formulated to help maintain the opacity of high pigment (HP) inks when being reduced. 
When adding reducers to opaque inks, use a minimal amount of reducer to help maintain opacity.  The recommended proportion of 1099LF is 1% to 10% by volume.