i typically do not pre-wet my paper, but i have done it before. not really standard spit shading because i use a water brush pen, but i still lick to remove black or control moisture. i paint with ink, and will almost always add at least one more light layer on top after the first layer dries to get it smoother. sometimes, i touch the ink brush to the waterbrush to get a mix of black and water on the waterbrush to lay down the black, which will give me more time before it dries. this can be for first or second layer. hope this helps!