Ammonium sulfate mixed with water, I think but Wilflex could confirm that a 2 or 3% solution ammonium sulfate to water solution works well for smoothing out the ink (we add the solution to the ink at 2-3%). We use it occasionally into inks that get gelatinous, although the Matsui Printgen MG could work for you too.
Have you ever used Matsui's RC waterbase? I've never used the CCI base, but have used Oasis soft base which is not so good as far as staying smooth. Matsui's RC which is the clear for transparent inks is really good stuff, it can go for hours on press without gelling or clumping. I find Matsui's pigments and formulas to be annoying to use, so if you're doing eye-ball matches, you might want to give the Matsui 300C (clear base) a try with your Rutland pigments.