Hi Dave, I use an airbrush for clear finishing. I use a water base clear Polycrylic (lowes or homedepot)
I haven't used inks, but have painted a little. Water base is a great way to go, but you have to be careful when thinning them. Too much water and they pull the grain of the wood up and you have to do a lot of sanding. Experiment is about the only advise. Always try it on scrap first