Well that's good. The metallic in the colour usually settles in the paint making it look darkerJohn My wife;s Mustang is metallic gunmetal gray,, and you can not see or find where the chips were. jimrayed when not. It also tends to streak when brushed, making it a little more visible. And you didn't mention him putting a clear over it. If the colour is single stage, no problem. If it's two-stage base clear, then the clear acts as a protectant for the colour. Most of today's base coats are water borne, making a clear over top essential to preserve the colour. The purpose of the razor blade is to eliminate the hih spots. Block sanding accomplishes the same thing. But I don't do this for a living or anything and you got good results. Can't argue with that.