I acquired two “mystery material” boards that are 24″ x 30″, with polished metal on one side (wrapping around the two long edges). The metal is probably stainless steel, the board material may be some kind of dense composite, but I don’t know if the dark charcoal grey color is a veneer, or throughout.
The above board has a painting on the back, dark composite, side, currently protected while I work on the metal. This is a new experiment for me: I am engraving the design using the power rotary tool and diamond burr bits. So it will be quite the sampler of textures as I play. I have sketched in a drawing using a Sharpie poster paint pen, but I am working the textures free hand, plus I am not staying inside the lines… it is a bit of a scribble, but fun.
I rubbed on a bit of magenta pigment just to see what I had done a bit better. The engraving raises a burr like drypoint work, so even loose powdered pastel clings to the edges.