True mer1122... Satin is a bit flatter than semi-gloss. But as stated, it ends up depending more on application.
I have had more success getting true flats with lower pressures in my air-brush -- i.e. 8psi
Small pressure chaanges affect the "flatness" of the finish. This can be an advantage when you want you subject to have different finishes in different areas,,, like different panels on a plane.
www.naplak.com/modeling ... a free site for modelers
www.scalehobby.com/forum/index.php ... a nice Modeling Forum