Lithograph and Giclee
Lithograph
This technique was invented in the 18th century. It used a porous limestone block, hence lithos meaning stone.
Depends upon the immiscibility of oil and water. Originally the image was drawn on the stone using tusche and litho crayon. The surface is fixed, moistened and inked. The areas of the stone, which do not bear the image, repel the greasy ink. The stone is pressed onto paper to produce the image. Fine art prints are still produced in this manner.
Nowadays commercial lithography uses a metal plate, which has been treated to render the surface porous. Exposure to an image hardens the coating on printing areas while the coating on non-printing areas is washed away, leaving wetted metal that will reject ink. The greasy ink applied to the plate adheres to the printing areas and when pressed onto paper the image is transferred.
Offset lithography involves the intermediate step of transferring (offsetting) the image from the plate to a rubber roller and then to the paper.
Giclee
Giclee printing is a recent introduction and is making a strong impact on the British print market. The giclee process starts in the same way as off-set litho in that the original drawing is scanned using a very high definition laser scanner but instead of making plates the information is fed into a computer and the image is printed using a very high quality, large format, inkjet printer called an iris printer - hence the name giclee which is French for 'to squirt'. New non-fading archival inks combined with the ability to print onto acid free, hot pressed watercolour paper similar to the paper used for the original drawings produces a superb quality print virtually indistinguishable from the original.
