Wood Cut. A form of relief engraving, where the parts of the image that are white or uncolored are carved away from the wood. An image is drawn directly onto a section of wood or on paper that is then transferred to a section of wood and carving is done parallel to the grain. If one thinks of a tree – it is cut lengthwise to form long planks. This would be the type of lumber used for a wood cut. Because of the direction of the grain, wood cuts did not hold up to modern printing presses and wood cuts could not be combined with metal or movable type in modern printing. Harper’s Weekly did not use wood cuts.
Wood Engraving: A relief printing process, like wood cuts. however wood engravings were carved from the cross-cut section of a hard wood tree trunk(boxwood was preferred). By carving on the end of the grain, the engraver enjoyed much more flexibility with tools and could exact very fine lines. By being perpendicular to the grain, cutting the wood in this manner, allowed the block to be inserted into the metal and movable types of the era. The compatibility of engraving and type made wood engraving the established printing process for nearly half a century. This was the image reproduction process used by Harper’s Weekly and the method by which Thomas Nast learned his trade. See a video demonstration of wood engraving here.
Lithography was the process of applying wax or grease onto a stone (less often a metal plate) and carving an image out of the surface application, and creating an image. A description below from the Philadelphia Print Shop, Ltd. :
The process is based on the principle that grease and water do not mix. To create a lithograph, the stone or plate is washed with water –which is repelled by the crayon– and then with ink –which is absorbed by the crayon. The image is printed onto the paper from the stone or plate, which can be re-inked many times without wear. A chromolithograph is a colored lithograph, with at least three colors, in which each color is printed from a separate stone and where the image is composed from those colors. A tinted lithograph is a lithograph whose image is printed from one stone and which has wash color for tinting applied from one or two other stones. Lithography is a planographic process and so no platemark is created when a lithograph is printed.
Lithography was invented by Alois Senefelder in 1798 but didn’t come into general use until the 1820s. After that time lithography quickly replaced intaglio processes for most illustrative and commercial applications, for the design was easier to apply to the stone or plate, it was much easier to rework or correct a design, and many more images could be produced without loss of quality than in any of the intaglio processes.
Lithographs and Chromolithographs were used to print the cartoons and colored cartoons for The San Francisco Illustrated Wasp, and its artist George F. Keller. Their experience with this form of printmaking originated from making cigar box labels.
For an excellent series on the history of printmaking, which includes details and examples of all these processes, I highly recommend viewing Richard Benson’s excellent videos for the MOMA. The videos are available in abbreviated segments (highlights), following the progressive history of printmaking, or you may view the eight-hour comprehensive look (which is broken up into segments for more defined viewing). The technique of Thomas Nast is explained at the 17-minute mark.