Ink Tack

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Instrumentation Test #1 – Inkometer Tack Test

Scope and Summary

The property tested was tackiness of ink in difference printing conditions. Both variable speeds and temperatures were recorded and analysed. This test helped determine and understand the relationship of ink in press running conditions (speed and temperature) and the tack property. Further research helped identify possible tack related problems and solutions.

The results showed up as expected in conjunction with the research found and previous tests on the tack property. The speed of the press greatly increased the tack while the temperature lowered it. Initially when recording early readings, the tack was much lower on the higher temperature setting (100 degrees Fahrenheit), but over the course of 10 minutes all results with the same speed setting showed a very similar value. The speed variable showed a much higher tack value both in the beginning and end of the 10 minute testing timeframe indicating that speed might have a greater overall effect on tack than temperature. Some suggestions to solve picking, which is induced from high tack, are to decrease the press speed, decrease pressure on the impression cylinder and reduce the tack. Some interesting findings have also given evidence that there are more modern methods, such as regulating the cylinders to help maintain the desired tack on a press.

Introduction

This test is just one characteristic on the many properties of ink. Tack is in close relations to ink film thickness, speed of the press, temperature of the press, and viscosity of the ink. Tack is an important characteristic of ink in that it helps determine the sharpness and clarity of an image. The objective of this test is to determine what the best recommended tack values are for sheet-fed and other means of printing as well as problems and solutions to tack related scenarios. Understanding some of the possible future or modern technologies or finding for ink tack is beneficial and crucial for this paper.

Definitions

"Tack - Resistance of a liquid to splitting. It is measured by determining the force required to split an ink film between two surfaces." (Pg 433, Wilson: 2005)

Viscosity is a measure of internal friction in a liquid; tack is a measure of internal cohesion." (Pg 284, Apps: 1958)

Equations

Slope = Rise/Run

Materials Used

O/S Pro Cyan – Colmar Inks Co.
Equipment Used
Electronics Inkometer – Model No. 101-A
Thwing – Albert Instrument Company
Pipette
Ink knives
Test Principle
The purpose of a tack test is to measure the resistance the ink has against splitting. In this particular test, the difference in tack at varying temperatures and at varying speeds is observed and compared. As the temperature is increased, more heat is transferred into the inks through the rollers. (Idminstruments) This creates various degrees of ink tack measurable on the machine. Since different forms of printing have different production speeds the tester can also be calibrated to simulate high or low speeds depending on the type of press it is used for. The equipment and procedures work similarly to press conditions, first the roller is run for one minute to warm up then when heat transfer and speed of the rollers are all reproduced on the tester, one can expect the same and accurate results to be found on a press. The procedures of reapplying ink on the rollers can be found to be similar to that of make-ready in production.

Procedure
1.Prepare a clean and organized work area with the necessary materials and equipment. 2.Obtain a preferable ink to use.
3.Adjust the Inkometer’s temperature settings to 90°F.
4.Set the speed to 800 RPM.
5.Set the ink tack value to zero by turning left on the knob while the machine is running. 6.Turn the Inkometer off.
7.Calibrate the pipette to 1.2CC. Fill in the pipette with the selected ink. 8.Apply the ink onto the rollers.
9.Turn on the...
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