The 12 Essential Terms for Automatic Press Calibration

Joe Clarke has spent the past 47 years in the lab and in the engineering department, in pre-press and on-press, as an R&D / technical researcher and as a manager of screen print production. Clarke has held executive positions as President of M&R Printing Equipment and as Vice-President at Wilflex [Poly One]. He has been granted a growing number of print-related patents, including one for High-Shear printing with Smilin'Jack - he is a member of the ASDPT, is an Associate Editor for NBM and an SGIA Fellow.

Clarke has presented hundreds of technical papers, written a couple books and published over 600 technical / management articles for which he has been awarded five Swormstedts; the international standard for excellence in technical writing.

Currently Joe Clarke is the President of CPR, a Chicago-based corporation which manufactures Synergy Inks including NexGen; environmentally & financially responsible T-Shirt inks. For more information on CPR, visit

Ink transfer is most often described as interface, variable, center pressure, pressure differential, and fluid pressure drop, but even so, these precise quantities are inconspicuous. Here are 12 terms to keep in mind when dialing in automatic press calibration.

1.            Line or input pressure from the compressed air is metered by and gauged at the regulator.

2.            Air pressure at a lower rate feeds into sealed pneumatic cylinders, which delivers force to the piston.

3.            Force from the piston causes a change in the motion of the blade. This is sometimes mistermed as “pressure.”

4.            Interface pressure on the mesh is equal to force, divided by the area at the first platen contact.

5.            Variable pressure in stroke or perpendicular axes occurs with poor press calibration.

6.            Center pressure is a lesser form of interface pressure due to traditional blades and bowed beams.

7.            Pressure differential occurs at the blade and forms a tight seal on the mesh to form a “pump.”

8.            Mechanical position adjustments don’t add or subtract pressure; they only limit piston travel.

9.            Net pressure on the platen equals resistance of the mesh, minus the pressure from the blade.

10.          Fluid pressure causes ink to thin and flow and is exerted by compressive and shearing force of the blade.

11.          Fluid pressure drop happens every time the ink reaches the mesh opening.

12.          Financial pressure is a result of one’s misunderstanding of the previous 11 definitions.