On reflection, there is a big difference between the Moran and Sedank images from yesterday, one has large blocks of primary colours, the other more subtle details.
Most of the posters that I have listed so far are somewhere between a 4 to 6 colour lithograph
The printing process which creates a lithograph is different from other traditional methods. Most printing presses require the printmaker to etch an image or text into metal plates or physically carve out the image on blocks of wood or other soft material. To create a lithograph, however, no etching is required. The artist uses a set of greasy crayons or pencils to draw a mirrored image of the original artwork onto a smooth stone tablet. This is by far the most time-consuming part of the lithograph process.
After the image has been recreated to the satisfaction of the original artist or other authority, it is ready to be turned into a lithograph. The lithographic process hinges on the principle that oil and water cannot mix. An oil-based variety of ink is applied directly to the plate and immediately bonds with the equally greasy crayon lines. Water is then wiped onto the remaining unpainted areas to discourage the ink from smearing. A sheet of paper is then placed over the entire plate. For a poster this is usually fairly thin, low quality but absorbent.
As we said before, these plates may be good for up to 1000 copies and this is most likely why a lot of posters seem to come up for sale with reasonably the same frequency.
Another factor for posters is size, in the UK for example, the process itself was developed by J Werner in London, Turner and Dunett were also a big printers in Liverpool.
Example of an early British Litho by Aubrey Beardsley
These early companies seemed to disappear during the poster boom and were repaced by larger companies such as Jordison’s and McCorquodale’s who developed the process on an industrial scale
McCORQUODALE’S PRINTING FACTORY
By 1886 McCorquodales of Wolverton was known as one of the finest printing factories in the country and employed 120 year women and 20 men. Most of the girls started work at the age 13 or 14 and were normally employed until they married. Girls were encouraged to remain in the factory as long as possible and a £10 wedding grant was given to those who had completed 10 years service. Until 1909 staff worked a 54 hour week starting at 6am with a half day on Saturday. The company were also quick to provide the best welfare and working facilities in the area, and the staff were provided with dining, reading and recreation rooms. A Good Samaritan Society was started and pension funds paid for holidays and service bonuses all made for a happy company.
A Jordinson poster from 1938 for London Transport
Post WW2 there was a boom in the offset litho process which could give an infinite number of colour combinations based on the ‘3 colour’ scale. Each city spawned a large number of offset companies and the days of the litho were numbered. For posters though the technique survived into the late 1960’s.