Please excuse any ignorance said here, I'm a new modeler and this was my first attempt at airbrushing/wash/clearcoats, etc, etc....
I had finisht my Tamiya Zero in a light grey version. Once I was through airbrushing (enamels) I applyed a good coat of Future. I then applyed my decals using testors decal set. They went on realatively nicely for a newbie. I then sprayed it with another good coat of Future. After waiting a day (there was at least a day between said steps above) I started to apply my wash. I decided to use an acrylic black (don't think this should have been a problem). I mixed roughly 90% water and 10% color (I don't think I had too much color). I started brushing along seams and panel lines. It looked ok, the black was going into the recessed lines and such. But some of the lines were so small that there is no way to paint just inside the lines. So I went ahead and lightly brushed over the lines. Several problems occured. One, as the paint dried, the color seemed to accumulated at the sides of the water line outside of the crack. Some stayed in the crack but most or a lot went to the edge of where the water had been brushed. Two, I tried to brush the excess off with water and if I did it to early when the paint was wet, it wiped off the color in the seam. If I waited too long, as I did for most of it, I can't get the color off, especially where I don't want it. I'm using just a water dampened napkin. Should I used some chemical? Three, the wash wanted to soak underneath decals when I applied the wash close to them, it ended up staining a good portion underneath several of my decals.
What did I do wrong? I tried to follow other peoples suggestions. I know you live and learn, but I think I just ruined my first model. Thanks for any help.