Hi @MalcTheOracle,
you missunderstood my request here 
I don’t need a solution for my nameplates. I already found an easy way to reach my goal here, by also taking the translucent issue into account (described in my post).
My question is only, if there is a way to disable that “feature” (I guess not).
Maybe a software developer will read this and creates a feature request for it? .
I did some tests with a 100x100 mm cube and yes, on the top side “only” 5 layers will be blended. If you color the front side, that blending goes thru the middle of the object. So it’s not even consistent.
I can’t see any sense in it. It contradicts exactly my goal to take the transparency of the filament into account. It leads to unneeded and unwanted color changes and increases the print time by factors.