According to the painter, I have a problem with the gap masses on the front two doors of my MK V. He told me that the gap masses must be at least 3 mm before painting so that there can be no paint chipping. What experience do you have with the gap masses?
Gerhard
Grūzi Geri,
Great to hear and see you have come that far in your project. 
I think your painter is right. Although the factory ROM talks about very thin gaps that may have been at the time due to the cellulose paints they were using. Of course a good painter knows hiw to avoid paint build-up on the edges and on holes, but with modern, very hard paints it may be safer with slightly bigger gaps.
I can’t say how many mm, it also depends where. I think the doors are the most important as they get opened and closed a lot.
Cheers!
A gap width of 3 mm or 1/8" sounds about right.
I’m having the most trouble with my right rear door, because this is the one where my original was bashed in long before I bought the car. I found a used door in Iowa, ok on the outside but rusted inside, and took apart both doors to get something I could use. I changed the outer skin but am using the original inner frame.
I have mounted a door from a donor vehicle, also with this the gap dimensions were not larger. For this reason I have mounted the original door again.