The Forge of the Vulcan and deep eyes , both are graphite on Yupo paper. Yupo paper is synthetic,"tree free" paper that is waterproof. You can find out more about it and it's uses HERE. The product is often used in marketing but it obviously has fine art applications.
Auad's work is linen, thread, (and in one piece, mother of pearl) in purple heartwood. Both Espelho para lemanja and Carranca Cavalo Marinho use this method. You can see the whole pieces and close ups of these subtle works below.