Lithography, a printing method invented in the late 18th century, literally means “stone printing.” It is a chemical process based on the simple principle that oil and water repel each other. This technique allows an artist to create intricate, hand-drawn images and reproduce them with a printing press. This guide provides a detailed, step-by-step overview of the traditional lithography process using a limestone slab.
Part 1: Preparing the Stone
The process begins with preparing the foundation of your print: a specially prepared, heavy limestone slab.
- Grinding the Stone: The surface of the stone must be perfectly flat and smooth. The old image is removed by grinding the surface with carborundum grit and water, typically starting with a coarse grit and moving to a fine one. The circular motion and weight of a smaller levigator stone or another stone help achieve an even surface. This is a physically demanding but crucial step.
- Washing the Stone: After grinding, the stone is thoroughly washed with a sponge and clean water to remove all traces of grit and residue. The stone must be completely dry before the next step.
Part 2: Drawing the Image
This is the creative phase where the artist creates the image directly on the prepared stone.
- Materials: Artists use grease-based materials to draw, such as litho crayons, litho pencils, and tusche (a greasy liquid ink). The strength of the image depends on the amount of grease applied.
- Drawing: The artist draws the image directly onto the stone’s surface. Where the greasy material is applied, it creates an area that will accept printing ink. The areas of the stone with no drawing will later be treated to repel ink.
Part 3: Etching and Gumming the Stone
This is a critical chemical process that chemically separates the image areas from the non-image areas.
- The Etch: A mixture of gum arabic and a small amount of nitric acid is applied to the stone. The acid “etches” the stone, making the non-image areas more receptive to water. The gum arabic then forms a thin, protective layer on these areas, sealing them.
- Washing the Drawing: The drawing material is carefully washed out with a solvent like mineral spirits. This leaves a ghost-like image of the drawing, but the greasy residue remains in the pores of the stone, which is what will hold the printing ink.
Part 4: Inking and Printing
With the stone prepared, the inking and printing can begin.
- Damping the Stone: The entire surface of the stone is lightly dampened with a sponge. The water is repelled by the greasy residue of the image and is absorbed by the gummed, non-image areas.
- Inking: A leather-covered roller is used to apply a layer of thick, oil-based printing ink. The ink adheres to the greasy image areas (which are still dry) and is repelled by the wet, non-image areas.
- Printing: A sheet of special printing paper is placed on the stone. Both are then run through a lithographic press, which applies very high pressure to transfer the ink from the stone to the paper.
Part 5: Final Steps
- Finishing the Print: The paper is carefully lifted from the stone, revealing the printed image.
- Post-Printing Care: The stone is wiped down and prepared for the next print or is ground down again for a new image. The prints are hung to dry.
The careful interaction of grease and water is the fundamental principle that makes lithography a beautiful and versatile printing method, producing unique and lasting works of art.
