A Comparative Study of the Environmental Aspects of Lithographic and. Digital Printing Processes. Sachin R. Kadam. Mary Anne Evans, Ph.D.

Transcription

1 A Comparative Study of the Environmental Aspects of Lithographic and By Sachin R. Kadam Digital Printing Processes Graduate Student, Enviornmental Health and Safety Management Mary Anne Evans, Ph.D. Professor, School of Print Media Sandra Rothenberg, Ph.D. Professor, College of Business A Research Monograph of the Printing Industry Center at RIT Rochester Institute of Technology No. PICRM

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3 A Comparative Study of the Environmental Aspects of Lithographic and Digital Printing Processes By Sachin R. Kadam Graduate Student, Environmental Health and Safety Management Mary Anne Evans, Ph.D. Professor, School of Print Media Sandra Rothenberg, Ph.D. Professor, College of Business Rochester Institute of Technology A Research Monograph of the Printing Industry Center at RIT Rochester, NY December 2005 PICRM Printing Industry Center at RIT All rights reserved.

4 With Thanks The research agenda of the Printing Industry Center at RIT and the publication of research findings are supported by the following organizations: bc ii Kadam, Evans, and Rothenberg (PICRM )

5 Table of Contents Introduction... 3 Background... 5 Evaluation Method... 9 Results Analysis of the Results Conclusion References Appendix A Appendix B Appendix C Appendix D Appendix E Appendix F Appendix G A Comparative Study of the Environmental Aspects of Lithographic and Digital Printing Processes 1

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7 I n t ro d u c t i o n The printing industry has been changing dramatically for over 20 years. While the majority of print volume is generated by offset lithography, many print operations are bringing in digital technologies as a complement or even replacement for some offset market segments. Amongst the advantages of these new digital technologies are the ability to produce variable data printing and economically viable short-run jobs. At the same time, societal, consumer, and regulatory pressures are driving all areas of industry to examine closely the effects of their operations on the environment. With the advancement and proliferation of digital technologies, the printing industry is looking forward to digital printing as a panacea for some significant technical and environmental problems that are currently associated with traditional printing methods. The two digital technologies showing the most growth potential are inkjet and electrophotography (Romano, 2003). Both technologies are developing the capability to approach offset lithography in image quality. High-end electrophotographic production presses are able to produce output at a rate which makes accessible some short-run offset market segments and there is significant development activity in this area from press manufacturers, software developers and consumables providers (The Print Extension, Inc., 2004) Volumes from conventional printing technologies will probably grow more slowly than those from digital technologies. Electrophotography is predicted to grow at about 2.8% and inkjet at about 8.3% for the period , compared with an increase in only 0.7% over this period for offset lithography (Business Development Advisory, Inc., 2003). However, issues of environment and workplace health and safety do not disappear merely because a facility is utilizing electrophotographic digital technologies rather than traditional printing processes. Moreover, digital technology has its own demerits that restrict its use for certain circumstances. It is essential for printers to know and understand how the environmental, health, and safety aspects of their digital printing operations compare to traditional printing technologies. In this paper we compare some environmental, health, and safety issues associated with lithographic and digital printing processes. Two commonly used press types, sheetfed lithographic and digital electrophotographic, have been studied to quantify material consumption, waste generation, and certain health and safety aspects at each stage of document production. Since the economic advantages of each technology relate closely to print run-length, the experiments were constructed around a long- and short-run framework. The objectives of this study were: To identify and analyze environmental, health, and safety (EHS) issues associated with lithographic and digital printing processes. To provide technical information, based on EHS observations and analysis, which printing companies can use when making technological choices. To raise awareness within the printing industry about material usage and waste generation resulting from print operations, thus creating a basis for integrating EHS into printing business management. To deliver a methodology by which a printing operation can perform a comparative environmental assessment of two different printing technologies. A Comparative Study of the Environmental Aspects of Lithographic and Digital Printing Processes

8 Introduction This research report provides guidelines from which a print technology comparison process can be derived for application to specific presses within a print production operation. Each print technology involves different technical considerations for the evaluation of materials and energy consumption and the generation of waste. Each press model based on similar technology and even the same model of press operated in two different production environments will show a different utilization of resources based on modifications, operation parameters, and the type of consumables used. The data generated in this study is of less significance than the methodologies used to generate, normalize and compare the data. Kadam, Evans, and Rothenberg (PICRM )

9 Background The printing industry uses various printing technologies for printing books, magazines, newspapers, business documents, catalogs, forms, etc. These technologies include lithography, rotogravure, flexography, screen, letterpress, and digital technologies including inkjet and electrophotography. The use of these technologies depends on the required quality of the print, number of impressions to be printed, availability of required resources, cost of the equipment, consumables cost per print, need to use variable content, and other factors. In this current environment of technological change, print volumes are migrating from conventional offset lithographic printing to digital printing. According to the U.S. Economic Census data, lithography was still the most commonly used technology in 2001 with a total of 15,038 firms using this technology (U.S. Census Bureau, 2001). However, the number of printing companies using lithography is declining as new technologies become available and new applications become accessible. Between 1999 and 2001, the number of offset presses operating in the U.S. declined by 21,000 a 12% decrease. The dominance of lithographic printing in the industry s recent history may be attributed to the efficient production of multiple and inexpensive copies, very high resolution and print quality, a wide range of coated and uncoated substrates, lower consumables cost per impression for longer run jobs, and considerable industry experience in color management (Cahill, n.d.). However, there are certain barriers for the continued dominance of lithographic technology including its very limited capability to do variable data printing, the associated prepress setup and preparation costs, higher cost per print for short run jobs, its potential to generate significant environmental and health impacts, and its considerable space requirements (Cahill, n.d.). The digital printing industry, on the other hand, is growing at a steady pace although so far it represents just less than 10% of U.S. print industry revenues (Romano, 2003). The driving forces for the adoption of this technology include minimal press setup time, variable data customization, image quality improvements, sophisticated screening algorithms, lower costs for short run, minimal space requirements, overall reduction in hazardous materials usage, reduced waste production, and the ability to transmit and collaborate on electronic print files all around the world (Cahill, n.d.). Despite these advantages, technology and cost, disadvantages remain that will keep significant print volumes in the traditional arena; these include generally slower throughput for digital technologies, higher cost per impression for longer runs, and in some cases, a requirement for specially prepared and coated substrates for optimal output quality (Cahill, n.d.). The migration to digital technology is partially hindered by the limited investment capital available to many printing companies. Also, many offset printers are small in size and employ fewer than 10 employees, most of whom are traditionally trained, so conversion from conventional to digital print technologies may be economically cumbersome. Lithographic printing is likely to remain a viable technology for the long term for static, long run jobs either as a standalone technology or as a component of hybrid production (Romano, 2003). Digital color printing is poised to grow significantly over the next five years with the primary growth driver being cost reduction (Fleming, 2004). A component of the anticipated cost reduction will be the management of EHS related issues related A Comparative Study of the Environmental Aspects of Lithographic and Digital Printing Processes 5

10 Background to the fixed costs of the marking technology hardware, and to consumables consumption and disposal. Environmental Awareness in the Printing Industry An awareness of environmental, health, and safety issues plays an important role in the identification of printing technologies for future investment. Lithographic printers may not be familiar with available government-supported environmental information programs, and may rely primarily on vendors, suppliers, customers and trade associations for such information (Rothenberg, Toribio & Becker, 2002). More than 80% of firms in the printing industry are small with fewer than 20 employees, below the level at which permanent environmental expertise can be brought in-house (Romano, 2003). In such companies there may be few resources to allocate to managing and planning environmental, health and safety issues. As competition increases, there may not be ready access to information required to support proposals and quotations for environmentally conscious customers. The printing industry has generated interest from environmental regulatory bodies and environmental protection groups for decades, due to in part to the sheer size of the industry (estimated to be in excess of $140 billion in revenues in the U.S. for 2002) (Romano, 2003) and in part to the array of chemicals and materials used (Rothenberg et al., 2002). In order to maximize the effectiveness of resource utilization, an effective Enviornmental Management System (EMS) should link into the entire print production cycle, and be incorporated into the planning, design, production, and distribution stages. There is a level of environmental awareness in the printing industry that makes it possible to make responsible choices. Print buyers are able to specify papers with a high recycled content, or to select grades produced in a totally chlorine-free process (TCF). Biodegradable inks based on natural substances such as soy may have lower solvent levels. In finishing, binding processes can be specified which enable full recycling of paper content without glue contamination. Distribution processes can be identified which minimize energy consumption in transportation. However, significant environmental issues remain. In lithographic printing, VOCs (volatile organic compounds) generated from the use of fountain solution, coating and cleaning solutions, and printing ink can contribute to the formation of smog the result of a complex photochemical reaction between VOCs and nitrogen oxides induced by ultraviolet light from sun. This pollution impacts the environment with negative consequences to humans, animals, and plants. Hazardous chemical emissions resulting from press and platemaking processes may cause both acute effects (e.g., eye, skin, or respiratory tract irritation) and long-term health effects on exposed workers. Particulate dust generated by paper handling and cutting, and spray powders used in printing and finishing may lead to long-term respiratory problems. Wastewater discharges of platemaking chemicals, waterbased coatings, etc., may lead to contamination of the groundwater system. Solid waste consisting of papers, used containers, etc., consumes landfill capacity. The hazardous waste disposal processes necessary to manage waste inks, solvent-laden cleaning materials, etc., are expensive and resource-depleting. These factors place a burden on the printing operation, and on society. Health and safety hazards in the printing industry mainly arise from chemical exposure and contact with hazardous machine components. Amongst the hazards caused by chemical exposure are occupational asthma, dermatitis, and in extreme cases brain damage. Press cleaning, solvent handling, and platemaking/reprocessing chemical exposures are the primary causes of dermatitis in printing industry employees (Printing Industry Advisory Committee, 2002). Exposure may result in acute effects (e.g., eye, skin, or respiratory tract irritation) or longterm illnesses such as cancer. Chemicals used in some specialized inks and adhesive materials may trigger occupational asthma (Graphical Paper and Media Union, n.d.). Anecdotal evidence indicates that digital processes that do not involve the production of color-separated masters or plates use less material in the overall production process than traditional methods requiring fixed plates. It is Kadam, Evans, and Rothenberg (PICRM )

11 Background also generally understood that digital processes require little or no makeready, and that the print-on-demand philosophy minimizes overruns (extra copies that are not needed). These two factors have given rise to the assumption that digital technologies consume fewer resources per impression than fixed-plate technologies such as offset lithography, flexography, and gravure. However, in practice it is known that material usage is involved in setup procedures on digital presses, and that significant waste can be generated in routine and nonroutine maintenance. The objective of this study is to investigate these precepts, and to compare two sheetfed presses which could potentially be used to produce similar print jobs; a sheetfed offset lithographic press (Heidelberg Speedmaster 74) and a liquid-ink digital sheetfed press (HP Indigo 3000). Our goal is to present a roadmap that can be followed by those wishing to provide their own comparative data on inhouse presses. A Comparative Study of the Environmental Aspects of Lithographic and Digital Printing Processes

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13 Evaluation Method In order to assess the environmental and health aspects and impacts of lithographic and digital printing presses, a mass balance approach was used to compare the materials consumption and waste generation of two sheetfed presses widely used in the industry, the Heidelberg Speedmaster 74 and the HP Indigo Since the variables of the study are known to be affected by run-length, the experiments were constructed around a long- and shortrun framework (500 and 3000 impressions). Presses were operated under conditions judged by experienced press operators to be as close as possible to normal, and the makeready and preparation steps were conducted so as to achieve a level of print quality that would be acceptable to most customers for documents of the type used. This introduced some subjectivity into the process, but efforts were made to generate measurably equivalent output quality from both presses. The general concept of a mass balance approach is to assess the total inputs in terms of energy, materials, consumables, etc., and to compare to these the output in terms of usable product, waste, and by-products. For each individual process the challenge is to derive appropriate metrics to encompass the input and output variables, and to calculate process efficiencies. In this study, the range of metrics and measured/calculated parameters were selected so as to be useful in evaluating the two technologies. After construction of a detailed process and material flow analysis (shown schematically in Appendix E), the following metrics were utilized: air emissions, including volatile organic compounds (VOCs) and hazardous air pollutants (HAPs); resource utilization and waste; lost material value (LMV); and noise. Target Image A common test target design was used similar to the type which would be used for general press function evaluations. The overall ink coverage was designed to be high so that consumption could be measured more accurately. Images were selected to clearly indicate tone reproduction, fine details, a color gamut which exploits the full range available with the inks used, and the standard image quality measurement elements such as grayscales, solid color patches, etc. In the offset process, screen angles and line screen selections were identified to be within the normal range generally used for images of this type. The image size was designed to be the same when output on both presses. In the makeready and press preparation process, acceptable print quality was determined by monitoring the optical density set points CMYK (1.45, 1.45, 1.10, and 1.75, respectively) with standard screen angles (15, 75, 0, and 45, respectively). Print order was YMCK. Resource Utilization and Waste Measurement Paper To assess the quantity of paper consumed, sheet count was used rather than mass due to the sensitivity of the paper in absorbing moisture from the atmosphere. Although the presses are operated under controlled environments, some mass differences due to humidity changes were observed over the course of the experimental work. For a final mass assessment the paper count was multiplied by the average sheet mass. Data was taken from the press counters and checked against retained waste and production sheets. Mass measurements were used to measure consumption of ink, coatings, solvent, and cleaning and fountain solutions. Initial and A Comparative Study of the Environmental Aspects of Lithographic and Digital Printing Processes

14 Evaluation Method final masses of containers were recorded to calculate the resource consumption and waste generation. Metrics specific to the HP Indigo 3000: Volumetric measurement techniques were used to measure imaging oil and imaging agent. In some cases, estimates of line volumes were calculated geometrically, and inaccessible tank volumes were explored with dipsticks before and after various stages of the press runs. The blanket and PIP (photo imaging plate) were weighed, and the usage for the press runs was calculated. Metrics specific to the Heidelberg offset press: Masses were recorded for the plate, ink reservoir liner, and offset blanket cleaning paper. Cleaning rags were separated and labeled in sealed, weighed bags for use in cleaning different parts of the press. After use, solvent-laden rags were returned to the same bags for weighing, and the residual ink and solvents used were calculated. Platemaking Kodak Polychrome Graphic plates (negative thermal polymer/aluminum) were used with the KPG Thermal Gold process. Details are given in Appendix F. Plates were exposed using an infrared laser in the platesetter, which causes the infrared dye and the accelerator agents in the sensitive layer of the plate to react, generating an acid which crosslinks the exposed polymer coating, rendering it non-soluble in the alkaline environment of the development process. Plates are then pre-baked at a high temperature to harden the polymer in image areas. Polymer in the nonimage areas is dissolved. Gum arabic or finisher is used to increase the water receptivity of the non-image area. Since the chemical usage for just one set of plates does not produce measurable changes in the platemaking system, chemical inventory data for a 3-month period was used to calculate the average amount of developer, replenisher, and finisher used in the process of making one set of plates. The calculated values were applied to the short and long run data sets on the assumption that the materials consumption is well-controlled. The waste generated is equivalent to the usage quantity since no regeneration or recycling is employed. Offset Press Cleaning Method The standard cleaning process was used. Inkote was applied over the plates to prevent the inks on the plates from drying. 1. Liner cleaning: The liners were taken out carefully and weighed for residual ink. Pre-weighed solvent-laden rags were used for cleaning the ink on the liners. Following use the rags were replaced in sealed bags and a mass difference determined. 2. Ink roller cleaning: The excess ink from the ink fountain was collected in pre-weighed collection dishes. Rollers were cleaned as described with the liners above. 3. Plates cleaning: Plates were taken out from the press and cleaned using a mixture of plate desensitizer, plate cleaner, and solvent. Ink/solvent-laden rags were sealed for weighing and the plates were sent for recycling. 4. Blanket and roller cleaning: Weighed, clean rags were soaked in solvent and used for the cleaning of the blankets, coating rollers, intermediate rollers, and other press parts exposed to ink in the press run. 5. Waste ink tray cleaning: Ink trays used for ink and solvent waste collection were taken out and the contents i.e. the mixture of ink and solvent were transferred to the weighed waste container. Ink trays were then cleaned using solvent-laden rags. 10 Kadam, Evans, and Rothenberg (PICRM )

15 E v a l u a t i o n Method Air Emission Monitoring Particulate Matter Emission The National Institute for Occupational Safety and Health (NIOSH) method 500 and method 600 were used for total dust and respirable dust monitoring respectively. Two types of sampling were conducted on each press. 1. Area sampling or total dust sampling: For area sampling, the samples were taken at the locations where the maximum concentration of dust was anticipated. For the offset press run, the sampler was fixed directly above the coating powder application zone (see Figure 1). For the digital press run, the sampler was placed near the exhaust end of the press (see Figure 2). 2. Personal sampling or respirable dust sampling: For personal sampling, the samplers were placed within the breathing zone of the operators in a location where significant time is spent during press operations. For the offset press run, the sampler was attached near the press outlet zone (see Figure 3). For the digital press run, the sampler was attached near the computer monitor of the controller station (see Figure 4). Figure 1. Total Dust Sampling for the Lithographic Press Volatile Organic Compound (VOC) Emissions. The NIOSH 1500/1501 standard was used for VOC monitoring. VOC sampling was conducted for both area and personal sampling in a manner similar to the particulate matter sampling. 3. Area sampling or non-breathing zone VOC sampling: For area sampling for the offset press, the sampler was fixed at the top of the ink tank (see Figure 5). For the digital press, the sampler was placed near the exhaust end of the press (see Figure 6). Figure 2. Total Dust Sampling for the Digital Press A Comparative Study of the Environmental Aspects of Lithographic and Digital Printing Processes 11

16 Evaluatio n M e t h o d 4. Figure 3. Respirable Dust Sampling for the Lithographic Press Personal sampling or breathing zone VOC sampling: For personal sampling, the sampler was attached to the shirt collar of the operator and the sample was taken at the time of offset press cleaning anticipated to involve maximum VOC exposure (see Figures 7a and 7b). For the digital press runs, the sampler was attached near the computer monitor of the controller station (see Figure 8). VOC and HAP Calculation Potential and actual volatile organic compounds (VOCs) and hazardous air pollutant (HAP) emissions were calculated from the results obtained during press runs according to the conditions outlined above. Potential VOC or HAP emission is calculated as the product of VOC or HAP content of the chemical, and the amount of the chemical used. The actual VOC or HAP emission is the product of potential VOC or HAP and emission factors corresponding to chemical type and application practice. The emission factors were based on a Graphic Arts Technical Foundation (GATF) guiding document (Jones 2001) and are summarized in Table 1. Noise Monitoring Noise monitoring was conducted using a noise dosimeter. The microphone of the sampler was clipped near the shoulder of the operator. Since these presses are not operated continually, monitoring was performed only for the duration of the press run. Figure 4. Respirable Dust Sampling for the Digital Press 12 Kadam, Evans, and Rothenberg (PICRM )

17 Evaluation Method No. Description Emission Factor 1 Lithographic ink Ink and other chemicals used in digital press Cleaning solutions applied without using rags Cleaning solutions applied using rags Coating solution (aqueous) Other 1.0 Table 1. VOC and HAP Emissions Factors Corresponding to Chemical Type and Application Practice, According to GATF (Jones, 2001) Figure 5. Non-breathing zone VOC sampling for the Lithographic Press Figure 6. Non-breathing VOC zone sampling for the Digital Press A Comparative Study of the Environmental Aspects of Lithographic and Digital Printing Processes 13

18 Evaluatio n M e t h o d Figure 7a. Breathing zone VOC sampling for the Lithographic Press Figure 7b. Breathing zone VOC sampling for the Lithographic Press Figure 8. Breathing zone VOC sampling for the Digital Press 14 Kadam, Evans, and Rothenberg (PICRM )

19 Results Short- and long-run press trials (500 and 3000 acceptable quality impressions) were conducted on both the Heidelberg Speedmaster 74 lithographic offset press, and the HP Indigo 3000 digital press. An appropriate level of makeready and preparation was implemented in order to produce prints with generally acceptable print quality. During each press run the masses and volumes of consumables were recorded. The results derived from these observations and measurements are summarized below. Materials Consumption Due to the makeready process involved (registration, ink/water balance, etc.) with the offset press runs, the overall paper usage is higher than the digital press for both the short and long runs. The difference is significantly greater with the short run, with the offset paper usage rate 3.7 times greater than the digital. In this data set this difference diminishes for the long run to a factor of only 1.1, but that is confounded by an unusually large number of waste sheets (600) in this experiment. The usable impressions for the offset short run comprise only about 25% of the total paper consumed. The usable rate for the digital short run is 95% (see Table 12. Resource Utilization Efficiency). In order to print six times as many impressions (500 to 3000) the offset ink usage increases by a factor of 1.4. This factor is 6.25 in the digital process. However, the total ink usage was lower for the digital press (0.5g/impression digital vs. 0.83g/impression offset). Based on longrun data, the materials consumption per usable impression is as follows: the fountain solution and aqueous coating solution usage in the offset press run averages out to 1.6g/impression and 0.6g/impression respectively. Approx 0.33g/ impression of cleaning materials and approx 0.6g/impression of cleaning rag usage were required along with 0.34g/impression of platemaking chemicals. These materials were not used in the digital press runs, which required about 0.7g/impression imaging oil, and about 6 mg/impression of imaging agent. The overall chemical consumption per usable impression (including consumed non-waste ink) for offset is about 3.7g/impression, compared with 1.2g/ impression for the digital process. However, for the short run, this consumption per impression soars to 16g/impression for offset, but remains low at 1g/impression for digital. These figures show that the consumables usage rate per impression is significantly higher for short-run offset than short-run digital, but that the difference diminishes with increasing run length. Waste Generation The principal component of waste is the paper used in makeready, which is significantly greater for offset (35-75% waste) than for digital (5-20%). Table 3 shows that ink waste contributes significantly to the overall waste generation in the lithographic process, contributing about 2.7g/impression and 0.5g/impression for the short and long runs respectively. The ink waste in the digital press run was minimal, as the unused ink is usually recycled. However, the digital press generates some ink waste during regular maintenance, and this was not accounted for in these calculations. The total quantity of waste generated from the cleaning and platemaking processes in the lithographic press run was assumed to be constant for both the short and long runs, since the setup and cleanup procedures are independent of run length. Dividing this quantity by numbers of usable impressions, the press cleaning chemical waste amounts to 2.7g/impression and 4.6g/impression for the long and short runs respectively. Excluding developer solution on the basis that it is used multiple times, the overall chemical waste including ink is approximately A Comparative Study of the Environmental Aspects of Lithographic and Digital Printing Processes 15

20 Results No. Parameter Lithographic Press Digital Press Short Run Long Run Short Run Long Run 1 Paper usage: a. Printed sheet count (acceptable quality) b. Wasted sheet count c. Total paper usage count Ink usage: a. Cyan ink usage (g) b. Black ink usage (g) c. Yellow ink usage (g) d. Magenta ink usage (g) Total (g): Fountain solution usage (g) N/A N/A 4 Aqueous coating solution usage (g) 300* 1800 N/A N/A 5 Cleaning solution usage: a. Solvent usage (g) N/A N/A b. Inkote usage (g) N/A N/A c. Plate cleaner usage (g) N/A N/A d. Plate desensitizer usage (g) N/A N/A e. Lithotine usage (g) N/A N/A f. Cleaning rags usage (g) N/A N/A 6 Platemaking chemistry usage:** a. Developer solution (g) N/A N/A b. Replenisher solution (g) N/A N/A c. Finisher solution/gum (g) N/A N/A 7 Imaging oil usage (g) N/A N/A Imaging agent usage (g) N/A N/A 3.14* * Indicates values calculated from long run results. ** Values calculated from process chemical inventory data. Table 2. Materials Consumption Kadam, Evans, and Rothenberg (PICRM )

21 Results 3.2g/impression for the long run and 7.3g/ impression for the short run. The digital process generates little comparative chemical waste of this type, but does generate solid waste components related to blanket materials (see Table 3) amounting to about 0.2g/impression for the long run and 1.1g/impression for the short run. It is in this area that some significant differences between resource utilization for lithographic and digital print processes can be seen. (See Table 3). Work Environment Conditions Results obtained from particulate matter and VOC (volatile organic compound) monitoring are summarized in Table 4. Both particulate matter and VOC emission levels are well below the required air quality standards listed in Table 4. The particulate matter emission was found to be almost the same for both technologies. However, in the breathing zone, the VOC emissions from the lithographic press (due primarily to the cleaning solutions) were found to be almost double the VOC emissions from the digital press. Overall, the indoor air quality was found to be within normal levels for both technologies. A Comparative Study of the Environmental Aspects of Lithographic and Digital Printing Processes 17

22 Results No. Parameter Lithographic Press Digital Press Short Run Long Run Short Run Long Run 1 Paper waste: a. Waste paper count b. Makeready waste count Total (Count): Ink waste: a. Skin ink waste (g) N/A N/A b. Excess ink from ink tank(g) N/A N/A c. Ink on spatula (g) N/A N/A d. Ink on liners (g) N/A N/A Total (g): N/A N/A 3 Liner waste (g) N/A N/A 4 Press cleaning waste: a. Waste blanket cleaning Paper (g) N/A N/A b. Waste ink & solvent on rags (g) N/A N/A c. Waste coating & solvent on rags (g) N/A N/A d. Waste ink & solvent in wash tray (g) N/A N/A e. Waste aqueous coating solution (g) N/A N/A f. Plate cleaner/preserver (g) N/A N/A g. Inkote (g) N/A N/A h. Litholine (g) N/A N/A 5 Press repair waste: a. Blanket waste (g) N/A N/A b. Metal stripes waste (g) N/A N/A c. Impression paper waste(g) N/A N/A d. PIP plate waste (g) N/A N/A Platemaking chemistry waste:** a. Developer solution (g) N/A N/A b. Replenisher solution (g) N/A N/A c. Finisher solution/gum (g) N/A N/A ** Values calculated from process chemical inventory data. Table 3. Waste Generation 18 Kadam, Evans, and Rothenberg (PICRM )

23 Results Generally the noise levels measured during press runs on both the lithographic and the digital presses are acceptable with respect to the standards listed in Table 5. However, at some point during measurement a peak noise level of db in was recorded in the offset press, crossing the 140 db OSHA limit. No. Particulate Matter Lithographic Press Digital Press Standard Level Short Run Long Run Short Run Long Run 1 a. Total particulate matter (mg/m 3 ) b. Respirable particulate matter (mg/m 3 ) < 0.8 < 0.8 < 0.9 < a < 0.3 < 0.3 < 0.3 < b 2 VOC as n-hexane: a. VOC emission outside breathing zone (mg/m 3 ) b. VOC emission in breathing zone (mg/m 3 ) N/A c d a. OSHA Time Weighted Average Permissible Exposure Limit (TWA-PEL) for total dust (U.S. Department of Labor, 1999). b. OSHA Time Weighted Average Permissible Exposure Limit (TWA-PEL) for respirable dust (U.S. Department of Labor, 1999). c. New York State Department of Environmental Conservation (NYSDEC) has a threshold limit of 5 tons per year (5 TPY) for VOC emission. No standard exists for VOC emission rate. However, the actual VOC emission figures from Table 6 shows that the VOC emissions from both the presses are well below 5 TPY (i.e. around 20 kg per day). d. OSHA and ACGIH (American Conference of Governmental Industrial Hygienists) have set emission limits for each individual VOC, and therefore, no standard exists for the total VOC exposure limit. Therefore, exposure limits for each individual VOC listed in MSDS relevant to cleaning operations are studied. Except glycerol and phosphoric acid that account for 2% of VOC components, all VOCs have ACGIH TLV- TWA limit of 100ppm (nearly 400mg/m 3 ) or above. Table 4. Indoor Air Quality Monitoring Results (in mg/m 3 ) No. Parameter Lithographic Press (db) Digital Press (db) Standard Level (db) 1 Peak noise level in db a 2 Time Weighted Average (TWA) in db b 3 Average sound level in db N/A 4 Run time (Hr:Min:Sec) 3:05:35 3:23:00 N/A a. OSHA peak noise level. b. OSHA Time Weighted Average Noise Level. Table 5. Noise Monitoring Results A Comparative Study of the Environmental Aspects of Lithographic and Digital Printing Processes 19

24 Results VOC and HAP Emissions Cleaning solutions used in offset press cleaning are a major source of VOC generation, contributing nearly 66% and 58% of total VOCs from the short and long runs respectively. Inks and imaging oil are also major VOC contributors in the digital press, contributing nearly 42% and 57% for the short run and 37% and 62% for long run operations as shown in Table 6. Details of the VOC calculations are given in Appendix A. Actual VOC emissions amount to 1.3g/impression for short-run offset, decreasing to 0.26g/impression for the long run as the overhead component related to cleaning solvent is mitigated. The digital press data shows 0.9g/ impression for the short run, rising to 1.0g/ impression for the long run, based on imaging oil usage which increases with run length. Lithographic Press Digital Press Chemical Type Potential VOC Emission (g) Actual VOC Emission (g) Actual VOC Emission (g)* Short Long Short Long Short Long Inks Imaging agent N/A N/A N/A N/A Imaging oil N/A N/A N/A N/A Fountain solution N/A N/A Coating solution N/A N/A Platemaking bath solution N/A N/A Cleaning solution applied with rags Cleaning solution applied without rags N/A N/A N/A N/A Total (g) * Same as potential VOC emissions. Potential VOC emission is the maximum VOC emission that the chemical can produce if its allowed to dry completely at high temperature for long period, whereas the actual VOC emission represents the emission value corresponding to the normal press operating conditions. **Sample calculation for VOC emission from imaging oil usage: Since the press temperature is much greater than the flash point of the imaging oil, full evaporation (emission factor 1.0) is assumed (see Appendix A). Therefore, Actual VOC emission = VOC content (%) x imaging oil usage (g) x emission factor = (95/100) x 1981 x 1.0 = 1882 g. Table 6. Potential and Actual VOC Emissions Actual HAP Emission (g)* Short Run Long Run HAP from fountain solution usage HAP usage per impression * HAP emission values are calculated from actual chemical usage and average HAP content from MSDS data. 20 Table 7. Potential and Actual HAP Emissions in the Lithographic Press Kadam, Evans, and Rothenberg (PICRM )

25 Results No. Waste Category Total Waste Quantity (kg) Waste Disposal Cost ($) Short Run Long Run Short Run Long Run 1 Paper waste disposal: a. Waste paper (kg) $0.020 $0.000 b. Makeready waste (kg) $ $0.540 Total: $ $ Ink waste disposal (kg) $6.071 $ Fountain waste disposal:* a. Fountain concentrate waste (kg) $0.443 $0.538 b. Fountain substitute (kg) $0.388 $0.470 c. Wastewater (kg) $ $ Total: $ $ Press cleaning waste: a. Waste blanket paper (kg) $0.011 $0.011 b. Waste rags (count.) $1.820 $1.820 Total: $1.831 $ Waste aqueous coating solution (kg) 0.767** $0.000 $ Platemaking waste disposal: a. Developer waste (kg) N/A N/A b. Replenisher waste (kg) N/A N/A c. Finisher/gum waste(kg) N/A N/A Total: Liner waste disposal (kg) $0.017 $ Plate waste disposal (kg) $1.767 $1.767 * Recirculation of fountain solution has not been taken into consideration. ** Value calculated from long run result. Negative (-) values indicate revenue from recycling. Total Waste Cost: $ $ Table 8. Waste Disposal Cost for the Lithographic Press. A Comparative Study of the Environmental Aspects of Lithographic and Digital Printing Processes 21

26 Results In this study, only the lithographic press generates hazardous air pollutants (HAP). The HP Indigo 3000 has no potential for HAP emissions under these conditions. The HAP component is 20butoxy ethanol in the fountain solution, and the use increases with run length. Note that ethylene glycol (present in the fountain solution concentrate and in the plate developer solution) is no longer regarded as a HAP. As shown in Table 7, this results in HAP levels of 0.12g/impression for the short run and 0.025g/impression for the long run, indicating that HAP emissions per usable impression decrease with run length. Detailed HAP calculations are shown in Appendix B. Environmental Cost Estimation Waste disposal costs were calculated by multiplying waste quantities by unit costs for the corresponding waste disposal methods. Waste disposal cost details are shown in Appendix C and calculations are summarized in Table 8. From these figures, it can be seen that the fountain waste cost is the most significant contributor, followed by ink waste cost. Fountain waste and ink waste disposal accounts for around 67% and 22% of total costs for the short and long runs respectively, with negligible differences between run lengths. This translates to disposal costs per usable impression of 5.4 cents for the short run, decreasing to 1.1 cents for the long run. Recycled sheets are allocated a negative cost based on incoming revenues. The total cost of these sheets is not recovered fully, even though the recycled material is efficiently sorted to maximize value. (See Table 8). As shown in Table 9, the digital press involves negligible waste disposal costs and waste disposal liabilities. Lost Material Value Lost material value (LMV) is a parameter that expresses the value of the resources lost in producing the product. This is calculated by multiplying the quantity of material lost by its No. Waste Category Total Waste Quantity (kg) Waste Disposal Cost ($) Short Run Long Run Short Run Long Run 1 Paper waste disposal: a. Waste paper (kg) minimal 2.99 minimal $0.272 b. Makeready waste (kg) $ $ Press repair waste: Total: N/A N/A -$0.006 $0.157 a. Blanket waste in kg(no.) 0.112(1) 0.449(4) $0.010 $0.040 b. Metal stripes waste in kg(no.) 0.023(1) 0.094(4) $0.002 $0.008 c. Impression film waste in kg(no.) 0.050(1) 0.050(1) $0.005 $0.005 d. PIP plate waste in kg(no.) 0.000(0) 0.054(1) $0.000 $0.005 Total: N/A N/A $0.017 $0.058 Total Waste $ Cost: $0.011 $0.215 Table 9. Waste Disposal Cost for the Digital Press 22 Kadam, Evans, and Rothenberg (PICRM )

27 Results No. Waste Category Total Waste Quantity (kg) Loss Material Value ($) Short Run Long Run Short Run Long Run 1 Paper waste: a. Waste paper (kg) $0.425 $0.000 b. Makeready waste (kg) $ $ Total: $ $ Ink waste disposal (kg) $ $ Fountain waste disposal:* a. Fountain concentrate waste (kg) b. Fountain substitute waste (kg) $0.377 $ $0.389 $0.472 c. Wastewater (kg) $0.000 $ Press Cleaning Waste: Total: N/A N/A $0.766 $0.931 a. Waste blanket cleaning paper (kg) $0.342 $0.342 b. Waste rags (nos.) N/A N/A Total: N/A N/A $0.342 $ Waste aqueous coating solution (kg) 0.767** $4.561 $ Platemaking waste disposal: a. Developer waste (kg) $3.655 $3.655 b. Replenisher waste (kg) $4.020 $4.020 c. Finisher/gum waste(kg) $2.002 $2.002 Total: N/A N/A $9.677 $ Liner waste disposal (nos.) 4 4 $1.600 $ Plate waste disposal (nos.) 4 4 $ $ * Recirculation of fountain solution was not taken into consideration. ** Value calculated from the long run result. Total Lost Material Value: $ $ Table 10. Lost Material Value in the Lithographic Press A Comparative Study of the Environmental Aspects of Lithographic and Digital Printing Processes 23

28 Results unit purchase price (see Appendix D). These values for the lithographic press are summarized in Table 10. The paper contribution to LMV is significant, contributing 51% and 37% to the total LMV for the short and long runs respectively. The plate and ink contributions are around 32% and 8% of total LMV for both the short and long press runs. The overall LMV amounts to 34 cents per usable impression for the short run, decreasing to just under 6 cents for the long run. This metric is a useful indicator in examining the relationship between waste consumption and run length. The lost material values for the digital press are tabulated in Table 11. Incorporating routine maintenance into the waste calculation, the blanket waste exerts a significant contribution to the overall LMV in both the short and long press runs. Including these factors, the LMV per usable impression amounts to 80 cents for the short run and 73 cents for the long run. These factors may not be applicable to every press run of this type. Paper waste contributes little to the overall LMV. No. Waste Category Total Waste Quantity (kg) Lost Material Value ($) Short Run Long Run Short Run Long Run 1 Paper waste disposal: a. Waste paper (kg) $0.000 $5.776 b. Makeready waste (kg) $0.734 $ Total: N/A N/A $0.734 $ Press maintenance waste: a. Blanket waste (no.) 1 4 $ $ b. Metal stripes waste (no.) 1 4 $0.000 $0.000 c. Impression film waste (no.) 1 1 $1.683 $1.683 d. PIP plate waste (no.) 0 1 $0.000 $ Total: N/A N/A $ $ Total Lost Material Value: $ $ Table 11. Lost Material Value in the Digital Press 24 Kadam, Evans, and Rothenberg (PICRM )

29 Analysis of the Results Resource Utilization Efficiency From the resource utilization and waste generation results, the efficiency of the major consumables used (i.e., paper and ink) is calculated and summarized in Table 12 and Figure 9. From Table 12 it can be seen that paper usage is significantly greater for the lithographic process compared with the digital process, due primarily to the materials consumption involved in makeready. Overall, the digital press has been shown to be superior to the sheetfed offset press in terms of material utilization. Though the digital press calculations indicate 100% efficiency in ink utilization, actual ink consumption for the long run is considerably greater than the extrapolated figure based on short run values. The actual consumption of yellow ink is much higher than expected from a short-run data extrapolation (Table 13). This was due to paper jams in the long run requiring blanket cleaning and evaluation using yellow ink (standard maintenance procedure). This loss of efficiency was included in the calculations since in the real world of production press operations, such events are not an uncommon occurrence. difference in Figure 11 is that the major portion of VOC emissions for lithography remain constant with run length, as they are associated primarily with the cleaning and platemaking operations. Figure 12 shows the relative contributions of fixed and variable contributions to the overall VOC levels in the lithographic press. For the digital press, all the contributions to the overall VOC emissions increase with the print volume and there are no overhead factors. Resource Type Resource Utilization Efficiency (%)** Lithographic Press Digital Press Short Run Long Run Short Run Long Run Paper Ink* * Ink loss in blanket and trays is not taken into consideration. ** Percentage of resource used in the final product. For example, in the lithographic process 26.16% of the total paper used for a short run gets used in the final product. These figures can vary depending on the experience of the operator, especially in case of the lithographic press. Table 12. Resource Utilization Efficiency Environmental Impact Although the VOC emissions from both presses are well below the regulatory emission standards described in Tables 4 and 5, the calculated VOC figures for the digital press are higher for long runs, due primarily to the imaging oil (Figure 10). The usage rate of the imaging oil increases with run length. In comparison the lithographic press inks have considerably lower VOC levels (13.24%), and this ink usage increases only slightly with run length. Additionally, the emission factor (i.e., the fraction of material emitted into the atmosphere) for lithographic inks is only 0.05, 20 times less than the emission factor for imaging oil at 1.0. Another contributing factor to the gradient Percent Efficiency Digital Paper Offset Paper Digital Ink Offset Ink Figure 9. Resource Utilization Efficiency (Paper and Ink) % Long Run Short Run A Comparative Study of the Environmental Aspects of Lithographic and Digital Printing Processes 25

30 Analysis of the Results VOC Emission (Grams) Press Run Length (No. of Prints) Digital Press Lithographic Press 3000 Figure 10. VOC Emissions from Lithographic and Digital Presses showing total emissions for each print run Only the lithographic press is of concern regarding HAP (Hazardous Air Pollutants) emissions, since the digital press uses no chemicals classified as HAPs. (Table 6). As with the VOC emissions, total HAP emission levels do not rise significantly with increase in print volume, and so the emission level per impression decreases (Figure 14). Environmental Cost The fountain solution waste disposal cost is a major contributing factor to the overall environmental cost in lithographic printing (Figure 15). The contributors to this are both the high volume of waste generated and the waste disposal cost based on the classification as hazardous waste. However, this cost does not increase significantly with increase in print volume. VOC Emission (Grams) Per Impression Digital Press Lithographic Press In comparison, the overall environmental costs are lower for the digital process (Figure 16). Although offset waste disposal costs per impression increase with print volume, overall they remain lower for the digital process. Therefore, it can be seen that digital technology has an advantage in terms of waste disposal costs, which are independent of print volume and run length. Press Run Length (No. of Prints) Figure 11. VOC Emissions Distribution in the Lithographic and Digital Presses showing VOC emissions per usable impression Ink Type Short Run Usage (g) Expected Long Run Usage (g)* Actual Long Run Usage (g) Difference (g)** Cyan Black Yellow Magenta * Values extrapolated from the short run results. ** Difference between actual long run usage and expected long run usage. Negative values indicate the usage of ink in excess of expected usage calculated based on short run usage values. Table 13. Analysis of Ink Consumption in the Digital Press 26 Kadam, Evans, and Rothenberg (PICRM )