Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1997 An investigation of the factors affecting dot gain on sheet-fed offset lithography presses Yung-Cheng Hsieh Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Industrial Engineering Commons Recommended Citation Hsieh, Yung-Cheng, "An investigation of the factors affecting dot gain on sheet-fed offset lithography presses " (1997). Retrospective Theses and Dissertations. 11465. https://lib.dr.iastate.edu/rtd/11465 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. 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This microform edition is protected against unauthorized copying under Title 17, United States Code. UMI 300 North Zeeb Road Ann Arbor, MI 48103 ii Graduate College Iowa State University This is to certify that the Doctoral dissertation of Yung-Cheng Hsieh has met the dissertation requirements of Iowa State University Signature was redacted for privacy. Major~T Professor[ J "V** -<-V ^ -w* Signature was redacted for privacy. For the Major Program Signature was redacted for privacy. the Graduate College iii TABLE OF CONTENTS LIST OF TABLES vi LIST OF FIGURES ix ACKNOWLEDGMENTS xii CHAPTER I. INTRODUCTION 1 Statement of the Problem 7 Purposes of the Study 8 Need for the Study 9 Research Questions 10 Research Hypotheses 11 Assumptions of the Study 13 Limitations of the Study 14 Delimitations of the Study 15 Definition of Terms 16 Abbreviations 21 CHAPTER II. REVIEW OF LITERATURE 22 Historical Overview of Offset Lithography 23 Current Offset Lithographic Practices 25 Four basic units of the offset press system 26 The printing unit 27 Overview of Dot Gain 29 Why is dot gain so critical? 30 What is total dot gain? 31 Measuring and Controlling Dot Gain 33 Densitometers 34 Dot gain measurement 36 What should the dot gain values be? 39 Factors Affecting Dot Gain 42 Prepress factors and dot gain 42 Press factors and dot gain 47 Ink and dot gain 53 Paper and dot gain 55 Summary 57 CHAPTER III. METHODOLOGY 58 iv Experimental Design 58 Variables of the study 60 Instrumentation 62 Measuring dot area on the film 62 Controlling plate exposure 63 Measuring dot area on the plate 64 Measuring dot area on the printed paper 66 Sampling 66 Data Collection 67 Analysis 68 Summary 70 CHAPTER IV. RESULTS AND FINDINGS 72 Research Objectives and Hypotheses of the Study 72 General Description of the Experimental Results 74 Dot gain measurement on the plates 75 Dot gain measurements on the paper 7 9 Results of the Hypothesis Testing 83 Hypothesis 1: mean effects on the 25% dots 83 Hypothesis 2: mean effects on the 50% dots 95 Hypothesis 3: mean effects on the 7 5% dots 105 Summary of the results of the hypothesis testing . 115 Additional Findings 116 Reliability and validity analyses 116 Dot gain phenomena on coated paper 120 Dot gain phenomena on uncoated paper 148 Summary for the additional findings 153 Summary 155 CHAPTER V. SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS 157 Surranary and Integration of Results 157 Hypothesis 1 159 Hypothesis 2 159 Hypothesis 3 160 Integration of the hypothesis test results 161 Additional findings 161 Integration of Findings with Past Literature 164 Convergence with past literature 166 Divergence with past literature 168 Contributions of findings to literature 169 Recommendations 172 Recommendations for offset printing personnel .... 172 Recommendations for further research 173 V APPENDIX A. DETAILED DESCRIPTIVE STATISTICS 176 APPENDIX B. PREDICTION OF DOT GAIN PERCENTAGES AT 25% TINT 183 APPENDIX C. PREDICTION OF DOT GAIN PERCENTAGES AT 50% TINT 185 APPENDIX D. PREDICTION OF DOT GAIN PERCENTAGES AT 75% TINT 187 APPENDIX E. BASIC DESCRIPTIVE STATISTICS FOR DOT GAIN VALUES ON THE COATED PAPER 189 APPENDIX F. PREDICTION OF DOT GAIN PERCENTAGES FOR THE COATED PAPER 193 APPENDIX G. BASIC DESCRIPTIVE STATISTICS FOR DOT GAIN VALUES ON THE UNCOATED PAPER 195 APPENDIX H. STEPWISE REGRESSION AND ANOVA TABLES FOR THE UNCOATED PAPER 199 REFERENCES 203 vi LIST OF TABLES Table 1.1. Factors affecting dot gain on offset presses. .. 6 Table 2.1. Typical dot gain values for three common printing conditions 40 Table 2.2. SWOP dot gain specifications 41 Table 2.3. FIPP dot gain specifications at the 50% tint. 41 Table 2.4. Midtone dot gain average by negative and positive plates 46 Table 3.1. 7} fixed factorial design of the study 60 Table 3.2, Experimental and controlled variables 61 Table 3.3. Table format for recording the data obtained from a single replicate 69 Table 3.4. Contrast constants for the 2^ factorial design..70 Table 4.1. Dot gain (%) (DG%) at three tints and solid ink density measurements of the plates 76 Table 4.2. General descriptive statistics for the dot gain values and SID 79 Table 4.3. Two-sample t and 95% C.I. for comparing the mean dot gain values among 25%, 50%, and 75% dots 81 Table 4.4. The mean dot gain percentages and solid ink density for the sixteen runs arranged in Yates (standard) order 82 Table 4.5. Estimated effects and coefficients, full model, 25% dots 85 Table 4.6. Analysis of variance, full model, 25% dots. ... 86 Table 4.7. Analysis of variance, reduced model, 25% dots. 88 vii Table 4.8. Estimated effects and coefficients, reduced model, 25% dots 88 Table 4.9. Estimated effects and coefficients, full model, 50% dots 97 Table 4.10. Analysis of variance, full model, 50% dots. ... 97 Table 4.11. Analysis of variance, reduced model, 50% dots. 100 Table 4.12. Estimated effects and coefficients, reduced model, 50% dots 100 Table 4.13. Estimated effects and coefficients, full model, 75% dots 107 Table 4.14. Analysis of variance, full model, 75% dots. .. 108 Table 4.15. Analysis of variance, reduced model, 75% dots. 110 Table 4.16. Estimated effects and coefficients, reduced model, 75% dots 110 Table 4.17. Summary of the test results for the hypothesis 115 Table 4.18. Table of the data arrangement for the reliability and validity analyses 117 Table 4.19. Correlation among the dot gain values for the ten measurements 118 Table 4.20. Principal components factor analysis without rotation for the ten measurements 120 Table 4.21. Estimated effects and coefficients of the full model for 25% tint on the coated paper 121 Table 4.22. Summary of multiple R and R square for dot gain at 25% tint on the coated paper 122 Table 4.23. Estimated effects and coefficients for the reduced model, 25% dots, coated paper 124 Table 4.24. Analysis of variance, reduced model, 25% dots, coated paper 124 viii Table 4.25. Estimated effects and coefficients of the full model for 50% tint on the coated paper 130 Table 4.26. Summary of multiple R and R square for dot gain at 50% tint on the coated paper 131 Table 4.27. Estimated effects and coefficients for the reduced model, 50% dots, coated paper 132 Table 4.28. Analysis of variance, reduced model, 50% dots, coated paper 133 Table 4.29. Estimated effects and coefficients of the full model for 75% tint on the coated paper 139 Table 4.30. Summary of multiple R and R square for 75% tint on the coated paper 140 Table 4.31. Estimated effects and coefficients for the reduced model, 75% dots, coated paper 141 Table 4.32. Analysis of variance, reduced model, 75% dots, coated paper 142 Table 4.33. General descriptive statistics of the dot gain values for the uncoated paper 14 9 Table 4.34.