Returnee query: Preshading - What is it?

Thanks for the update. Interesting.

I used to run a bit of pastel chalk on a Q-tip along the panel lines for the same effect. But lightly, as this can be easily overdone. So maybe just working the centers of larger panels with lighter shades and highlighting the panel lines as Ive always done would be an alternative?

It's a method of laying down black along panel lines before doing the base color to show the effect of paint fading from the center of panels before the edges. It is a controversial technnique, to say the least. There's a discussion here about how easily it can be overdone resulting in quite unrealistic models, in the opinion of many. Of course ,if you do several color cmao schemes, the effect is lost.Or if you lay down a good layer of paint, it's lost. And it's lost behind decals, as well.