The traditional Japanese method of woodblock printing calls for carving one block for each color, although in practice a printer will often designate areas for more than one color on a block if the areas are far enough apart to be inked accurately. But for the most part, it's one color per block.
As I've begun to work with very large prints and blocks of wood, more and more often I've found myself seeking ways to save money and time by consolidating my materials, and one way I've found to save on wood is to use the reduction method whenever possible. The reduction method involves carving a block, printing that block on all the sheets of paper in the planned edition, then carving ("reducing") the block more, printing again, carving again, and so on until the image is completed.
Last week I started a new print in my "Loaded" series of prints about money, and I'm using the reduction method to create an image of a car that will be central to the print. Below are photos of the first two printed colors from the initial reductions, plus a photo of the block carved for a third time and ready to print. There will be one more reduction after this one.
First, a pale blue impression of the whole shape of the car. Then I went back and carved again.
Next I printed a gray layer.
Today I finished the third "reduction" and tomorrow (hopefully) I'll print it using another tone of gray.