The final test on printing inks requires a method of application and of peripheral conditions that are as close as possible to those used later in the printing process.

Trial printing on a large printing machine would be cumbersome and hence costly. Simulating printing trials are therefore essential during product development and for pre-run tests.
Printing trials on a l reduced scale are therefore commonly used, employing special appropriate small machines which are able to simulate the conditions of the full scale process.