I masked a spot on my modell (which is already painted and future coated) that needed touching up.
Airbrushing went fine not too visable, no ragged edges.. exept there is a very slight step up of either paint or future or both. A lighted edge and shaded edge is visable. Maby the decal sealing layer (future) and dull cote layer will hide it.
Othervice all i'm thinking of is "sloping the hill" so to speak by carefully sanding on the edge.. and if that doesn't work, edge rubb with tops touched with windowcleaner or maby toothpicks.
OR is coats all that's needed?
What's your experiance :) .. (darn it i want to decal already)