Lately, I have been painting with Humbrol, but even if I thin out the paint I have been getting a very slight sandpapery finish. In times past, even their flat paints seemed to have a slight gloss mixed in and the pigment was ground finely enough that once the paint was applied it was extremely smooth and did not require any buffing out by wet sanding. Will mixing in a bit of gloss help at all or some other technique? I have liked Humbrol in that it dries to a hard shell finish that stands up well to corrections or weathering with mineral spirits. Many thanks!