In Painter 7.1 Liquid Ink, I sometimes get light-colored fringe where a new color is added onto existing color areas. This happens only occasionally, but when this starts to happen, the file must be once closed to correct the problem. The follows are examples.
I first painted the light pink circle to the left, (I used the Soft Camel Variant), then applied the light green from the outside of the pink area. A whitish fringe appeared on the former edge of the pink circle.
The strokes I used are like this.
Another example. In this case, the color first painted was green.