My thought is the dark panel lines are really just shadows in the gap between two panels, however small. So I use pure black for panel lines on the spec and power maps. Panel Edge glare layer is a rough duplicate of the panel line layer, offset 1px down and 1 px back, these are pure white in Soec file but I play around with the opacity until I get something I’m satisfied with. It Varys depending on the darkness of the base metal, and how much grime there is, etc.