Keeping Background layer lines on top

[samuelw45059948]

How do I keep the outline drawing lines on my background layer always on top, so that if I use airbrush on them on another layer, the black outline lines will always remain on top? If I move the background layer to the top, it is opaque, Thanks.

[Jeff Arola]

Set the Layer Blending Mode of the "outline drawing" layer to Multiply

[samuelw45059948]

Thx