This document summarizes an ink tack analysis test performed on an inkometer. The test measured how ink tack changed over time at different roller speeds and temperatures, simulating press conditions. Results showed ink tack increased over time at 800 RPM but peaked then decreased at 1200 RPM as heat caused tack to fall. Recommendations discussed maintaining proper tack values and sequences for quality printing.

1. INK TACK ANALYSIS
Travis Drew – Madalyn Krapez-Fewster
RYERSON UNIVERSITY
GRA 534 – SECTION 01
Instructor: Martin Habekost
October 26th
, 2015
Word Count: 1276

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Table of Contents
Theory............................................................................................................................................. 2
What are we testing?.................................................................................................................. 2
Definitions and Equations........................................................................................................... 2
What is the theory and concept behind this test? ..................................................................... 2
What is your expected outcome? What are the educational gains? ......................................... 3
What are the practical applications of this test?........................................................................ 3
Results and Interpretation.............................................................................................................. 3
Equipment Used.......................................................................................................................... 3
Materials Tested ......................................................................................................................... 3
Test Procedure............................................................................................................................ 3
Results......................................................................................................................................... 4
Discussion.................................................................................................................................... 4
Recommendations...................................................................................................................... 5
References ...................................................................................................................................... 6
Appendix ......................................................................................................................................... 7

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Theory
What are we testing?
For this test, we are focusing on re-creating the effects that press speed and temperature have
on ink tack. This test will replicate what occurs when ink is placed under these conditions and
how to prevent them before it becomes a problem. This test will be performed on the Thwing-
Albert Instrument Company Inkometer and will be testing the Flint Group – Arroweb Mid-Tack
Cyan ink.
Definitions and Equations
Ink Tack: Ink Tack is the force of splitting an ink between two surfaces (i.e. ink rollers or printing
nips) (Pdhajny, 2002)
Ink Stability: The broad collection of pigment, powder coatings, and ink products that exist in
harmony within an ink. (Pigment, Powder Coatings and Ink Applications, 2010)
Gram- Meter: A unit of energy equal to 100 gram-centimeters. (The American Heritage®
Stedman's Dictionary, n.d.)
What is the theory and concept behind this test?
Ink Tack is the main focus within this test, as it is a standard quality control measure on press.
Ink Tack is the stickiness of an ink and it measures the force that you need to split an ink film in
two (Todd, 2007).
We know that Ink Tack is important because it can directly affect both the quality and
production of a printed job while on press. This test scales these issues down and simulates on
press performance so that we can measure these issues and understand how to prevent them.
For example, Ink Tack can easily be affected by decreasing the speed of the press, or warming
the press up, and vice versa (Todd, 2007). These are important characteristics to understand
because when you are printing on different substrates (such as thin paper), you must adjust
your ink tack for optimal printing conditions.
This test also looks at Ink Stability. We are measuring the ink tack over time to show just how
stable the ink is. If this test proves that over time, the tack wildly decreases, it will prove that
there is a very low ink stability. Optimally, on press you want an ink that will yield a high ink
stability to allow for long runs (Pigment, Powder Coatings and Ink Applications, 2010).

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What is your expected outcome? What are the educational gains?
For this test, we are predicting that over the duration of the run, the ink tack will increase
rapidly between the two tests. This is because when you are working with ink tack, increasing
the speed of the press simultaneously increases ink tack. Therefore, when we increase the
Inkometer from a speed of 800 to 1200 RPM, the ink tack should also increase.
From this test, we will duplicate on press conditions to learn the effects of ink tack. This will
then allow us to take this knowledge and understand how to prevent tack-related problems on
press.
What are the practical applications of this test?
This test is important because it is a direct representation of on-press conditions. When you
measure how the ink tack was affected, you are able to better predict its variables on press.
The Inkometer stimulates different conditions that ink would be put under, (i.e. a fast press run,
a slow one and different temperatures). Therefore, after we complete this test we will be able
to understand the relation between speed, time and temperature and how it relates to ink tack.
This test is important to our industry because ink is one of the foundation building blocks to
good print quality as well as smooth press runs. If we have an inking error, it could completely
ruin our entire run. Therefore, it is important to complete this test so that in the future, the
knowledge of ink tack and stability can be applied to different press runs.
Results and Interpretation
Equipment Used
Thwing-Albert Instrument Company - Inkometer (Model 106)
Inkometer Pipette
Materials Tested
Flint Group – Arroweb Mid-Tack Cyan
Test Procedure
1. Ensure all rollers are thoroughly cleaned with no leftover ink or solvent.
2. Set the temperature on the heating unit to 90 degrees Fahrenheit.
3. Set the roller speed to 800 RPM. Pres the green on/off button to turn on the timer, set
the timer to 30 seconds.
4. Fill the pipette with 1.2cc of ink and transfer ink to the middle rubber roller.
5. Engage both the lower and upper rollers onto the main roller.
6. Manually turn the rollers around once to disperse the ink.
7. Press the run/stop button to start up the rollers.

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8. Turn off the rollers and timer after 10 minutes have passed and collect the printed data
sheet with ink tack values.
9. Repeat steps 1-8 but instead setting the roller speed to 1200 RPM.
Results
Discussion
According to the results shown above, the ink tack for web offset ink generally increases over
time on press. At 800 RPM, the ink tack increased from 3.7GM to 12.3GM, which is a total net
increase of 8.6GM. After assigning a trend line to the data we found the slope of the line to be
0.98, representing an average change of 0.98GM per minute. This increase took place between
the 1 minute and 10 minute mark. The same ink running at 1200 RPM had similar results, the
ink tack consistently increased over time until the 7.5 minute mark in which it peaked at
12.8GM then began to decrease until the test concluded at 10 minutes.
According to Printing Industries of America ink tack should change approximately +/-1.0 gram-
meter unit from one sample to the next and no more than +/-2.0 (Printing Industries of
America, 2015). This aligns with our results as the slope for both 800 RPM and 1200 RPM are
0.98 and 0.76 which are within close proximity to 1.0. The average ink tack at 800 RPM was
8.3GM, the average ink tack at 1200 RPM was 10.4GM. According to Dr. Richard M. Podhajny,
the speed considered for web offset inks should be 1200 RPM and the average ink tack should
rest around 10.0GM (Podhajny, 2002). This aligns very closely to our results which showed an
average ink tack of 10.4 GM at 1200 RPM.
These results support our expectations going into the test. In accordance with Stefans law, the
faster the press, the higher the ink tack. Inversely, as the temperature increases, the ink tack
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0
InkTack(GM)
Time (minutes)
Ink Tack at 800 and 1200 RPM
800 RPM @ 90F 1200 RPM @ 90F
800 RPM Slope= 0.98 1200 RPM Slope= 0.76Figure 1 – Table in Appendix

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decreases. This can be observed in the 1200 RPM run, as the rollers were spinning faster they
began to heat up causing the ink tack to decrease. (Encycolpedia Britannica, 2015)
Recommendations
Ink tack is an extremely important factor to consider with regards to runability. Improper ink
tack can lead to problems such as picking and linting in which paper fibres are pulled from the
press sheet. Uncoated substrates, such as newsprint, are especially sensitive to high ink tack
and require inks with lower tack values. In order to ensure consistency you need to know the
“tack stability curve”, which is what was measured on the inkometer in this test and shown in
Figure 1. This represents how the tack value changes over time as the rollers in the press
constantly shear and split the ink affecting its tack properties. (Savastano, 2009)
Ink tack impacts the trapping of inks on press which affects printability. It is important to
ensure that your process CMYK inks have the correct tack values and are laid in the correct
sequence for proper trapping. (Pritchard, 2009) According to Nancy Plowman Associates,
“There should also be adequate tack separation between the cyan, magenta, and yellow. Good
tack separation is defined by 25-50 difference between the inks, starting with the cyan being the
highest and descending from there.” (Nancy Plowman Associates, 2015)

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References
Encycolpedia Britannica. (2015). Stefan–Boltzmann law. Retrieved from www.britannica.com:
http://www.britannica.com/science/Stefan-Boltzmann-law
gram-meter. (n.d.). The American Heritage® Stedman's Dictionary. Retrieved from:
http://dictionary.reference.com/browse/gram-meter
Inkometer 1100. (2015). Retrieved from www.thwingalbert.com:
http://www.thwingalbert.com/inkometer-1100.html
Nancy Plowman Associates. (2015). Ink Testing . Retrieved from npatest.com:
http://npatest.com/testing-capabilities/ink-testing/
(n.a.) (2010) Pigment, Powder Coatings and Ink Applications. Retrieved from:
http://www.horiba.com/scientific/products/particle-
characterization/applications/pigments-inks/
Podhajny, D. R. (2002, October 1). What Is the Role of Tack in Printing Inks? Retrieved from pffc-
online.com: http://pffc-online.com/ar/487-paper-role-tack-printing
Printing Industries of America. (2015). Testing Your Ink. Retrieved from www.printing.org:
http://www.printing.org/page/10638
Pritchard, G. (2009, July 13). Ink Sequence - 4/C process & beyond. The Print Guide.
Savastano, D. (2009, October 2). Analyzing Offset Inks. Retrieved from Ink World Magazine:
http://www.inkworldmagazine.com/issues/2001-08/view_features/analyzing-offset-
inks/
Todd, R. E. (2007). Measurment of Ink Tack. Retrieved from
http://studentsupport.biz/page306.html

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Appendix
TIME (MIN) 800 RPM @ 90F 1200 RPM @ 90F
1.0 3.7 5.5
1.5 4.4 6.2
2.0 4.8 6.8
2.5 5.4 7.6
3.0 5.9 8.3
3.5 6.3 9.1
4.0 6.8 9.7
4.5 7.3 10.4
5.0 7.9 11.0
5.5 8.3 11.5
6.0 9.0 11.9
6.5 9.4 12.4
7.0 9.9 12.6
7.5 10.5 12.8
8.0 11.0 12.7
8.5 11.4 12.7
9.0 11.7 12.3
9.5 12.0 11.9
10.0 12.3 11.3
SLOPE 0.98 0.76
AVERAGE 8.3 10.4