Ink Water Balance

Ink / Water Balance?
David Daffern

Hostmann-Steinberg

Introduction

• For most lithographic printers, Ink / Water Balance is a fundamental part of their lives. • What does the ink maker see? • The interaction between ink and fountain solution

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Qualifications

• What qualifies an Ink Maker to discuss the day to day frustrations of Pressman? – Experience –Communication – An ability to see the “Big Picture”? – A commitment to the Graphic Arts industry

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Overview

Scum Dot Gain

Catch up

Loss of highlights

Balance ?

Piling

Fluctuation Density

Drying

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How does the ink maker see Ink / Water Balance?

• • • •

Water Pick Up EmulsificationPotential Complicated Viscosity? Effects of Fountain Solution Concentrate and Alcohol Replacement / Wetting Agent? • Water Window?

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Water Pick Up

• A wild and wacky test designed by ink makers to give some meaning to emulsification • Not really relevant to the Lithographic Process • What does it mean

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Duke Water Pick Up Tester

Hostmann-SteinbergDuke Water Pick Up Tester

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Duke Water Pick Up

100 90 80 70 60 % 50 40 30 20 10 0 0 2 4 6 8 Time Ink A Ink B 10 12 14 16

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What Does Water Pick Mean To You?

• Used extensively as a QC test for inks • Only real use is to provide a degree of consistency to the ink • The value reported is not the real number

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WaterPick Up Percentage

Water Pick Up 10 20 30 40 50 60 70 80 90 100

Actual amount of water 9.09% 16.67% 23.08% 28.57% 33.33% 37.50% 41.18% 44.44% 47.37% 50.00%

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Factors that affect Water Pick Up?

• • • •

Varnishes Pigments Additives Fountain Solution

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Emulsification Potential

• A means of measuring the viscosity change in an ink asfountain solution is slowly added • May be used to evaluate the differences between inks or fountain solutions.

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Lithotronic Emulsification Tester

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Em ulsification curve
80 2000 70

60 1500 50

1000

40

30

500

20

10

0 0 2 4 6 8 10 12

0

Time
Torque Water % Temperature 2 per. Mov. Avg. (Torque)

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W a te r%

T o rq u e

Emulsification curve
700 80

70 600 60 500 50

400

40

30 300 20 200 10

100 5 6 7 8 9 10 11

0

Time
Torque Water % 2 per. Mov. Avg. (Torque)

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W a te r %

T o rq u e

Is Emulsification Potential Important?

• On the press the average amount of emulsification of an ink is only 7%! • For light take off this number will increaseover time if the ink is not replenished

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Emulsification curve
700 10

9 650 8

7 600 6

550

5

4 500 3

2 450 1

400 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 6

0

Time
Torque Water % 2 per. Mov. Avg. (Torque)

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W a te r %

T o rq u e

Factors that affect EP?

• • • •

Varnishes Pigments Additives Fountain SolutionHostmann-Steinberg

Complicated Viscosity?

• Complex Viscosity is a frequency-dependent viscosity function determined during forced harmonic oscillation of shear stress • For Example, Ink coming off a plate or blanket is subject to harmonic oscillation – The frequency depends on the speed of the press (IPH)

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Functional Forms Of Viscosity
• • • • • • • • • • • • • • • •Apparent Viscosity Coefficient Of Fluidity [Fluidity] Coefficient Of Viscosity [Viscosity] Complex Viscosity Differential Viscosity Dynamic Viscosity Infinite Shear Viscosity Inherent Viscosity [Logarithmic Viscosity] Intrinsic Viscosity [Limiting Viscosity Number] Kinematic Viscosity Out-Of-Phase Viscosity Plastic Viscosity Reduced Viscosity [Viscosity Number] Relative Viscosity [Viscosity Ratio]...