What you use to set decals should depend in large part on the decal. Most after market decals will set just fine on a flat, gloss coated surface with Micro Set. Surfaces that have compound curves or irregular surfaces might take a shot of Micro Sol. I find that kit decals are, for the most part, much tougher to get to settle into the surface and can take a shot of Micro Sol just to settle on a smooth regular surface. Some decals just won't settle under ether Sol or Set, in that case you can try something like Solvaset or what I use distilled vinegar. All are good additions to the toolbox.