When I draw my koi, I must “hatch” them, drawing the dense parallel lines that go this way and that. I love hatching the fish. The colors get woven, one color layer atop the next. The effects are mutable, changing before your eyes.
To hatch the colors means being ready for surprise. You never quite know what the color effects will be. And yet it’s thrilling seeing the color changes happen as you watch, and the not-knowing gives you joy.
Aletha Kuschan's Weblog 
I love your hatching lines, they give a lot of depth, must be an optical effect with light bouncing on them.
Thank you, Ben. Merci beaucoup.