Spit-bite aquatint is a process of "biting" the plate with a brush dipped in a nitric acid/water mix; then brushing this directly on a plate that has melted rosin on it. The plate doesn't have to be immersed in an acid bath, so it allows for a direct interaction with the plate. The nitric acid erodes the metal between the globules of melted rosin, creating pits in the metal. When the acid is fully expired on the plate, it is sponged off and the plate is then cleaned to rid it of the melted rosin. This pitted metal holds the ink when the plate is "wiped", so the ink remains only in the areas the spit-bite has been. This technique is called spit-bite because long ago, the printmaker would put the brush in their mouth and use their spit as a vehicle for the acid. We've learned a lot about safety since then, but the name has remained. It's a wonderful process because it's very painterly and has a unique look to it in which the image has a distinguished, soft sfumato edge. I love it.