door panel lines

Preshading panel lines is difficult to get right sometimes, and one of the reasons that I avoid using that technique.

I'd advise using a very thin wash of either artist's acrylic or artist's water colors (these are available at any art supply store). Thin them very thin with water, and add a couple of drops of dishwashing detergent. Stir well (and stir occasionally), dip a fine point paint brush in the mix, and touch it to the panel line. The wash will run along the line. Any excess that gets outside the panel line can be removed with a moistened Q-tip rubbed ACROSS the panel line (not along it). Note that for this to work best the surface needs to be smooth. Not necessarily glossy, but a flat surfeace will not work well at all.