Get a set of different color Sharpies , pick a color close to the paint of your model and drag the Sharpie along the cut edge of your decal then let it dry for an hour before dipping the decal in water . The color of the Sharpie doesn't need to be a perfect match , as long as it's a similar color the edge will disappear . I've been doing this for a while and it works great ! And don't use Flairs or other brands of markers , they all run in the water no matter how long they dry . Sharpies are the only markers that are truly water proof .