Rochester Institute of Technology RIT Scholar Works Theses Thesis/Dissertation Collections 6-1-1975 Studies of the Characteristics of Different Grained Surfaces on Some Typical Lithographic Wipe-On Plates Porntawee Pungrassamee Follow this and additional works at: http://scholarworks.rit.edu/theses Recommended Citation Pungrassamee, Porntawee, "Studies of the Characteristics of Different Grained Surfaces on Some Typical Lithographic Wipe-On Plates" (1975). Thesis. Rochester Institute of Technology. Accessed from This Thesis is brought to you for free and open access by the Thesis/Dissertation Collections at RIT Scholar Works. It has been accepted for inclusion in Theses by an authorized administrator of RIT Scholar Works. For more information, please contact [email protected]. STUDIES OF THE CHARACTERISTICS OF DIFFERENT GRAINED SURFACES ON SOME TYPICAL LITHOGRAPHIC WIPE-ON PLATES by Porntawee Pungrassamee A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in the School of Printing in the College of Graphic Arts and Photography of the Rochester Institute of Technology June, 1975 Thesis adviser: Dr. Julius L. Silver School of Printing Rochester Institute of Technology Rochester, New York CERTIFICATE OF APPROVAL MASTER'S THESIS This is to certify that the Master!s Thesis of Porntawee Pungrassamee with a major in Printing Technology has been approved by the Thesis Committee as satisfactory for the thesis requirement for the Master of Science degree at the convocation of June, 1975 Thesis Committee: Name Illegible Thesis Adviser Name Illegible Graduate Adviser Name Illegible Director or Des....... i-g-n-a":'""te--- ACKNOWLEDGEMENTS I wish to thank Dr. Julius Silver, thesis adviser, for his guidance in this research work. This study would not have been possible without his help. My thanks, also, to Mr. Chester Daniels and Mr. Mil ton Pearson for their technical advice. I am grateful to Azoplate, Richardson Graphic, Summer Williams and Western Litho Plate Companies for supplying the plates used in this research. I would like to thank Professor Bekir Arpag for his help in the beginning of this study, and thanks to the members of the Thesis Committee for spending their valuable time on the proposal and the final report. Special thanks to Ms. Monica McCormick, a Photographic Science student, who did all the photomicrographs in this report. 1 1 TABLE OF CONTENTS Chapter I INTRODUCTION 1 Statement of the Problem 1 Objectives 2 FOOTNOTES FOR CHAPTER I 3 II REVIEW OF THE LITERATURE 4 Surface Characteristics of Grained Lithographic Plates 4 Wettability and Contact Angle of Lithographic Plates 6 FOOTNOTES FOR CHAPTER II 8 III DESIGN OF THE EXPERIMENT 9 Experimental Procedures 9 Printing Quality Measurements 12 Hypothesis 16 FOOTNOTES FOR CHAPTER III 16 IV RESULTS AND ANALYSIS OF DATA 17 Surface Characteristics of Grained Aluminum Plates 17 Microscopic Examination 17 Coarseness Measurement by the Sheffield Smoothchek 30 ii i 70 Degree Gloss Measurement 30 Coating Thickness 37 Printing Sharpness 38 Resolution Measurement 38 Tone Reproduction 54 Wettability of Grained Aluminum Plates ... 54 Image Adhesion 64 FOOTNOTES FOR CHAPTER IV 66 V. CONCLUSIONS AND RECOMMENDATIONS 68 Characteristics of Grained Surfaces 68 Printing Quality 69 Plate Performance 69 Image Adhesion 70 FOOTNOTES FOR CHAPTER V 71 APPENDICES 72 A. WETTABILITY AND CONTACT ANGLES OF LITHOGRAPHIC PLATES 73 FOOTNOTES FOR APPENDIX A 75 B. PRELIMINARY TEST ON COATING WIPE-ON PLATES . 76 C. EXPOSURE TIME OF THE TEST PLATES 78 D. ALUMINUM PLATE GRAINING AND ANODIZING 79 FOOTNOTES FOR APPENDIX D 83 E. MULTIPLE RANGE TEST 84 FOOTNOTES FOR APPENDIX E 87 F. PRINTING CHARACTERISTIC CURVE 88 FOOTNOTES FOR APPENDIX F 90 iv G. INK DOT SCUM ON ALUMINUM PLATES 91 FOOTNOTES FOR APPENDIX G 92 H. MATERIALS USED IN THE EXPERIMENT 93 I. EXPERIMENTAL EQUIPMENT 95 FOOTNOTES FOR APPENDIX I 97 BIBLIOGRAPHY 98 LIST OF TABLES Coarseness of the Grain Measured by the Sheffield Smoothchek 31 2. Summary ANOVA for Grain Coarseness 33 3. Comparisons of Individual Means of Grain Coarsenesses 34 4. 70 Degree Gloss Measurements 35 5. Coating Thickness of the Grained Plates 38 6. Summary ANOVA for Coating Thickness 39 7. Multiple Range Test for Coating Thickness 39 8. Printing Sharpness of Chemically Grained Plates 40 9. Printing Sharpness of Anodized Plates 41 10. Printing Sharpness of Brush Grained Plates 42 of Grained Plates .. 43 11 . Printing Sharpness Sandblast 12. Variance Analysis for Printing Sharpness 44 13. The Widths of Center Solid of Printed GATF Star Target Measured with 8X Glass 46 14. The Widths of Center Solid of Printed GATF Star Target Measured with 40X Microscope 48 15. Resolution of the Grained Plates 50 vi 16. Summary ANOVA for Resolution of the Grained Plates 50 17. Multiple Range Test for the Resolution Measurements 51 18. Contact Angle of Uncoated Plate 57 19. Coating Thickness of Brush Grained Plates 77 20. Exposure Time of the Test Plates 78 21. SSR Value for Coating Thickness . ., 86 22. SSR Value for Resolution Measurement 86 23. Printing Plates Used in the Experiments 93 vn LIST OF FIGURES 1. Coarseness Measurements Pattern 10 2. Plate Coating by Whirler 10 3. Diagrams of the Apparatus for Measuring Contact Angles 15 4. Areas for Contact Angle Measurements 15 5. Photomicrograph of the Brush Grained Aluminum Plate (Wipe-0 Plate) at 150X 18 6. Photomicrograph of the Brush Grained Aluminum Plate (Azoplate) at 150X 19 7. Photomicrograph of the Chemically Grained Aluminum Plate (Granite Grain) at 150X 20 8. Photomicrograph of the Sandblast Grained Aluminum Plate (ST Plate) at 150X 21 9. Photomicrograph of the Anodized Aluminum Plate (Azoplate) at 150X 22 10. Photomicrograph of the Anodized Aluminum Plate (John Stark S-31) at 150X 23 11. Photomicrograph of the Brush Grained Aluminum Plate (Wipe-0 Plate) at 400X 24 12. Photomicrograph of the Brush Grained Aluminum Plate (Azoplate) at 400X 25 viii 13. Photomicrograph of the Chemically Grained Aluminum Plate (Granite Grain) at 400X 26 14. Photomicrograph of the Sandblast Grained Aluminum Plate (ST Plate) at 400X 27 15. Photomicrograph of the Anodized Aluminum Plate (Azoplate) at 400X 28 16. Photomicrograph of the Anodized Aluminum Plate (John Stark S-31) at 400X 29 17. Densities of the Solid Patches Printed from Two Chemically Grained Plates 53 18. Printing Characteristic Curves of the Grained Plates (set 1 ) 55 19. Printing Characteristic Curves of the Grained Plates (set 2) 56 20. Contact Angles of the Printing Plates During the Press Runs (set 1) 58 21. Contact Angles of the Printing Plates During the Press Runs (set 2) 59 22. Contact Angles of the Sandblast Grained Plate During the Press Run 60 23. Diagrams of Image Removal on the Grained Plates 65 24. Interfacial Tension 74 IX STUDIES OF THE CHARACTERISTICS OF DIFFERENT GRAINED SURFACES ON SOME TYPICAL LITHOGRAPHIC WIPE-ON PLATES by Porntawee Pungrassamee An Abstract A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in the School of Printing in the College of Graphic Arts and Photography of the Rochester Institute of Technology June, 1975 Thesis adviser: Dr. Julius L. Silver ABSTRACT Four different types of grains of wipe-on lithographic plates (mechanical grains, a chemical grain and an electro lytic grain) were studied. The experiments were divided into two parts. The first part concerned surface characteristics of the grained plates, and the second one involved plate performance on a press. plates' The grained characteristics, including coarseness, gloss, directionality and depth of grain, were examined mechanically, optically and visually. The limitation of each method was discussed. The effects of the surface structures on coating thickness were reported. The experiments on the press were designed to find which grained plate produced the best printing qualities, such as printing sharpness and resolution. Their tone reproductions were reported graphically. Changes of wettability of the plates during the press run were investigated by contact angle measurements. The factors that caused the change of the contact angles were discussed. The wear of the images on the plates were tested under conditions of increased abrasion. Most of the data were analyzed by statistical techniques such as analysis of variance and multiple range 2 tests. Under the experimental conditions, the printing sharpnesses and the tone reproductions of the test plates were alike. The chemically grained plates have higher resolution, compared to the anodized and the sandblasted plates. The c hem i cal g r a i ned and the san d b 1 as t g r a i ned p 1 at e-s have better image adhesion than do the brush grained and the • anodized plates, but their hydrophilic properties change faster than do the latter types. Abstract approved: Name Illegible Thesis Advise:" Name Illegible Title and Department ~i\ -"'1~---­~ 2- 7,117l 7 Date CHAPTER I INTRODUCTION Lithographic wipe-on plates have been in use for 20 years employing diazonium resins which are the same as those used on some presensitized plates. The aluminum plates, normally, are of very fine grain. (Ball grains are also available but these plates are classified as having a coarse grain.) The special treatment for zinc plates has been developed by the Graphic Arts Technical Foundation but this metal is rarely used in the wipe-on system. The advantages of the aluminum plates are ease in processing, ease in handling on a press, lower cost and fewer problems in storage. Statement of the Problem Quality control systems are important in printing reproductions. To set up or maintain the quality of reproductions, materials used in the reproduction process must be investigated. Printing plates are one of the important materials that have effects on the quality of reproductions. Therefore, their capabilities, printing quality and performance on a press, require study. Various grained plates for wipe-on process are available.