I just started using an airbrush, and saw the "AppleBarrel" acrylic's were dirt cheep . So I tried them out on this airplane...
I thinned the paint with this.
Got this stuff at Hobby Lobby. Say's it's for thinning Acrylic's.... seem's to work ok...... but I'm still "Expirimentin" with it.
I have had several people suggest "Windex" for thinning Acrylic paint, but I havent tried that yet.