Duoshade paper has two set of lines embedded. You have two chemicals you paint the paper with to reveal those lines. One chemical reveals one set of lines and other both sets of lines. In video Cartoonist Kayfabe show how it works. I didn’t know this was a thing before Cartoonist Kayfabe started to talk about the technique in their earlier videos. At the end of the video has link to video where they explain the technique.
Video’s title warns us we might get jealous to try this. I didn’t get jealous. I got inspired. Last two weeks I have been going through Corel Painter video course. I wasn’t that interested of paper textures, dab stencils or flow maps until I watched the video. After watching if I went to Painter and started to play with paper textures and dab stencils. I think I need duoshade texture to use in my black and white art.