Hi Chuck
As well as being a modeller, I am also a Coatings Chemist. You can use the Tamiya X-20A thinner which is a mixture of Isopropanol & a glycol ether solvent (the glycol ether slows down the evaporation rate of the Isopropanol). I use Isopropanol on its own, mixing two parts paint to one part thinner.
Tamiya acrylic paint does not brush well, even when thinned!