An inkometer is a specialized measuring instrument used by the printing industry to measure the "tack" (adhesiveness) of an ink with the roller system on an offset press. The importance of tack is that it is not so excessive that it doesn't allow effective transfer from the rollers to the plate and then to the blanket and on to the substrate being printed. Inks can also be tack "graded" in descending sequence to allow for better trapping of one color over another. Inks with too much tack can cause the surface of the paper to pick off and interfere with transfer on subsequent printing units and copies.
The amount of tack can be controlled by changing the amount of solvent or other diluent used in the ink.
The inkometer is made up of three rollers. The center roller is a temperature controlled brass roller, the bottom roller is an oscillating rubber distribution roller. The top roller is attached to a load cell which measures the tack. Instruments can be adjusted for various roll speeds which are meant to simulate specific press speeds based on the printing process. High speed web publication inks are typically run at 2000 rpms. Standard web fed publication and commercial web inks and some sheet fed ink are run at 1200 rpms (Sheet speed measurement such as FPM is required for this to be meaningful). Traditionally sheet fed ink has been run at 800 rpms (Sheet speed measurement such as FPM is required for this to be meaningful).