EPA744-F-01-001 Design for the Environment February 2001 

Gravure Partnership 

The Effect of Ink Temperature 

On Solvent Losses and Print Quality 

Background—The U.S. Environmental 

Protection Agency’s (EPA) Design for the 

Environment (DfE) Program, the University of 

Tennessee (UT) Center for Clean Products 

and Clean Technologies, and Western 

Michigan University (WMU) partnered with 

the Gravure Association of America (GAA), 

gravure printers from the packaging and product sectors, and other industry experts to identify 1) common environmental issues for 

gravure printers, especially small- and medium-sized businesses in the packaging and 

product sectors; and 2) potential risk reduction 

and pollution prevention opportunities for 

addressing key issues. 

Packaging and product gravure printers are 

particularly concerned about solvent losses 

from ink during press operations—including 

solvent losses from the ink sump and ink pan 

areas—which might be reduced by controlling 

ink temperatures. Smaller gravure printing 

operations generally use a press-side sump to 

pump ink to the press, where the ink may 

absorb heat from 

the ambient air or U.S. Gravure Industry Statistics from press operaSector # of plants Avg. presses tions. Large publi­ per plant cation printers 

Publication* 24 6.3 generally have inPackaging 276 2.5	 line heat exchangers and closed- Product 174 2.8 

loop ink delivery Total 480 2.8 

systems, which are Avg. employees per plant** <20 not as subject to 

Annual sales ($/yr)** >$18 billion	 solvent losses from 

elevated ink temData from 1987-1993 (GAA Profile Survey of the U.S. Gravure peratures. The Industry). 

Gravure Partner­ * 2000 data from GAA. ship performed a 

**Data for publication, packaging and product combined.	 preliminary study 

of the effect of ink 

temperature on solvent losses and print quality, 

which is summarized below. The results suggest that packaging and product printers could 

reduce solvent losses, and, in some cases, 

improve print quality by controlling ink temperatures. Further study by the industry is 

needed to confirm these results. 

Gravure Industry Statistics—The gravure 

industry comprises three main sectors: publication, packaging, and product printing. 

Publication gravure plants are generally large 

operations that tend to be more automated, 

with more advanced systems for addressing 

environmental concerns. Packaging and product gravure plants are often small- to mediumsized printing facilities with fewer employees, 

fewer presses, and more limited resources. 

Risk Reduction Opportunities—The partnership began with a scoping phase to identify 

potential opportunities for packaging and 

product printers to reduce emissions and risk 

from printing operations. Project partners consulted with GAA and industry experts to 

develop a preliminary list of risk reduction 

opportunities (see box, page 2), which were 

then verified through site visits to gravure 

printers in the packaging and product sectors. 

DfE project leaders chose to study the effect of 

ink temperature on VOC emissions and printability for the following reasons: 

•	 Ink temperature’s effect on solvent losses 

and print quality are common problems 

among various packaging and product 

printers, in spite of different inks, number 

of colors, and substrate. 

•	 By controlling ink temperature, printers 

might gain print quality and cost benefits 

as well as environmental benefits. 

1 
•	 Emissions from the ink sump and ink pan areas are Gravure Partnership Purpose—The purpose of the DfE 

not always captured by air pollution control equip- Gravure Partnership was to 1) identify risk reduction and 

ment attached to presses. pollution prevention opportunities for addressing key envi­

•	 Reduction in the use of hazardous air pollutants ronmental challenges in the gravure industry, 2) determine 

(HAPs) and VOCs could reduce adverse impacts on whether promising risk reduction techniques might also 

human health and the environment (due to direct tox- have cost and/or performance benefits, and 3) provide the 

icity from HAPs and indirect effects of smog forma- risk, performance, and cost data to the gravure industry for 

tion from VOCs). further technology verification. 

Following scoping, a laboratory experiment was conducted at WMU’s Printing Pilot Plant to explore the rela- Risk Reduction Opportunities tionships between ink temperatures, solvent losses, and Risk reduction opportunities identified by the DfE print quality (Sosa, 1999). The results of the WMU tem- Gravure Partnership include: perature control study, presented here, provide preliminary • Volatile organic compound (VOC)/solvent emis­ information to the industry on the potential risk, perform­ sions reduction ance, and cost benefits of ink temperature controls. 

- from floor cleaning 

- from press operations Temperature Control Study 

• Hazardous waste generation Purpose • Shop towel management 

The purpose of the preliminary laboratory study was to 

evaluate the effects of temperature on solvent consumption 

WMU Temperature Control Study and print quality. 

The WMU laboratory experiment met key objec- Method tives of the DfE Gravure Partnership by: 

Two colors of nitrocellulose (Type C) ink common to • Developing information on the effects of ink 

packaging printers were used in 3-hour production runs on temperature on solvent consumption and print 

a 42”, 4-color gravure press at 300 ft/min. Type C inks are quality. 

generally ester or ketone inks. The solvent blend used in • Determining that technologies to moderate or the temperature experiment was 50% normal propyl control ink temperatures are a worthy subject acetate and 50% normal propyl alcohol (by volume). for further investigation by the industry. Samples were taken for the two inks at three different ink 

temperatures: 66oF, 79oF, and 92oF. 

The cooler temperature was obtained by Study Parameters 	 Variable conditions 

using cold water and ice to cool water Controlled conditions	 (average ink temperature) circulating through copper coils sub- Press size: 42" wide, 4-color press 66°F (cooled with cold water and ice) merged in the ink sump. The warmer Press speed: 300 ft/min 79°F (ambient) temperature was obtained by circulating Substrate: 1.25 mil polyethylene film 92°F (heated with hot water) hot tap water through the copper coils. Run length: 3-hour production run No temperature controls were used for (samples taken every 20 Measurements taken 

the middle (ambient) temperature, minutes) 	 Viscosity (adjusted every 5 minutes) which increased by 3oF to 5oF during Ink type: Type C (nitrocellulose), Solvent consumption the course of the 3-hour run. magenta and cyan Ink consumption 

During the runs, ink temperature Solvent blend: 50% n-propyl acetate, Printability 

was measured and viscosity was tested 50% n-propyl alcohol (by • Optical density 

• Gloss	 and adjusted every 5 minutes. Print volume) 

• Microstructure image analysis (dot quality measurements were taken every Initial ink vol.: 60 lb (solvent + ink) 

structure) 20 minutes. Several measures of print­

• Tonal response	 ability were obtained. (See Study 

• Rub resistance (Sutherland Ink Rub	 Parameters Box.) 

Tester) 

2 Gravure Partnership 
Solvent and Ink Consumption Results Figure 1 Total Solvent Consumption Colder ink needs more solvent to bring it to target 

viscosity, but as temperature rises, the solvents in solvent-based inks evaporate faster and require more solvent to maintain viscosity (Sosa, 1999). 

•	 Total solvent consumption (solvent added during 

makeready plus solvent added during the print run) 

in the magenta ink increased with increasing temperature (see Figure 1). 

•	 Total solvent consumption in the cyan ink was slightly greater at 66oF than 79oF due to the amount of 

solvent needed to reach target viscosity during makeready. Solvent consumption increased from 79oF to 

Solvent Consumption (lb/hr)

3.5 

4.2 4 4 

11.8 

7.2 

Magenta 

Cyan 

66°F 79°F 92°F
 

92oF (see Figure 1). 

•	 Total mass (ink plus solvent) consumption 

increased with increasing temperature: 9%-28% 

increase from 66oF to 79oF and 37%-56% increase 

from 79oF to 92oF. 

Ink Temperature 

Figure 2 Ink Consumption 

ready or the trial) also increased as temperature rose 

(see Figure 2). The increase in ink consumption at 

higher temperatures may be due to the higher pigment to solvent ratio of warmer ink, which prints a 

thicker layer. 

Print Quality Results 

In the WMU study, printability and quality were 

affected as ink temperature increased, with both printed solids and tones affected (Sosa, 1999). 

•	 Reflection Density—dropped by 0.055% of reflected 

•	 Ink use (not including solvent added during make­ 7.8 Ink Consumption (lb/hr)

1.6 

4.5 

3 

5.6 

4 

Magenta 

Cyan 

66°F 79°F 92°F light for every 5oF temperature increase from 79oF 

to 92oF (see Figure 3). Theoretically, ink at higher Ink Temperature 

temperatures should print darker colors, but 

reduced reflection densities at higher ink temperatures have been reported elsewhere (Celio, 1998). Figure 3

Warmer inks evaporate faster, which can cause a Print Quality — Reflection Density

wettability problem and screening. Screening is a 

print defect caused by uneven flow of inks between 

cells (GAA, 1991). In the WMU study, as ink temperature rose to 92oF the ink dried before spreading adequately on the substrate, thus reducing the 

overall printed solid area and the reflection density 

(Sosa, 1999). Printed tone steps were most affected; 

the finest dots did not print at all. 

•	 Specular gloss—decreased by 20% from 66oF to 

79oF, but increased by 3% from 79oF to 92oF (see 

Figure 4). Colder ink requires more solvent to reach 

Reflection Density (%) 

2.05 

1.98 

1.7 

Cyan 

target viscosity; lower pigment concentration leads 66°F 79°F 92°F


to a thinner printed ink film. In the WMU study, Ink Temperature 

the specular gloss measurements for the colder ink 

3 
were influenced by the glossy polyethylene 

substrate showing through the thinner ink 

film. The increase in specular gloss seen 

from 79oF to 92oF may be due to the 

decreased wettability and increased screening observed at higher temperatures. 

Screening may have caused more light to be 

reflected from the polyethylene substrate. 

•	 Dot structure (see Figures 5 and 6)—hot 

inks had deformed dot structure caused by 

the “donut effect.” As ink fills the engraved 

cells of a printing cylinder, it forms a concave shape leaving an air bubble to be 

trapped between the ink and the substrate. 

The air prevents the ink from being transferred to the middle of the printed dot and 

forces the ink to be spread outward, creating 

a “donut.” Warmer, less viscous ink produces a bigger concave meniscus as it lies in 

the cylinder cells, which results in more air 

being trapped and a larger donut. As the 

donut effect increases with temperature, the 

amount of printed image decreases and the 

printed dot becomes bigger (Sosa, 1999). 

Deformed dots caused by the donut effect 

also had bigger perimeters. As the dot 

perimeter increases so do the dot gain and 

mottle, causing a decrease in print quality. 

Finally, photographs taken in the solids 

areas confirmed the reduced wettability of 

the hotter ink; the white, non-printed areas 

of the solids rose with increasing ink temperature. 

•	 Haze—not a quantifiable variable in the 

WMU study, but appeared to increase with 

decreasing temperature. Decreasing efflux 

time and/or doctor blade pressure may 

reduce haze. 

•	 Rub resistance—no change in rub resistance 

at different temperatures. A Sutherland ink 

rub tester was used to rub the printed films 

against a white surface for a specific amount 

of time. The reflection density of the white 

surface was measured before and after the 

test to determine the amount of ink transferred from the printed film to the surface. 

The difference in the reflection densities of 

the hottest temperature and the coldest temperature inks were within the resolution of 

the densitometer. 

Figure 4 Print Quality — Specular Gloss Specular Gloss (%) 

73.5 

61.1 63 

Cyan 

66°F 79°F 92°F
 

Ink Temperature 

Magenta elongated tone (25%) Figure 5

— 150 lines per inch 

79°F	 92°F 

Cyan compressed tone (25%)	 Figure 6 

— 150 lines per inch 

79°F	 92°F 

Figure 7 Magenta solid — 150 lines per inch 

79°F	 92°F
 

4 
Conclusions Study Limitations 

The WMU study assessed the effects of • The WMU laboratory study was designed to evaluate the potential risk, performthree ink temperatures (66oF, 79oF, and ance, and cost benefits of ink temperature controls for gravure printers. The 

92oF) on solvent consumption and print study does not establish a definitive relationship between ink temperature, solquality of Type C inks under laboratory-con- vent emissions, and print quality. 

trolled conditions. The study was designed to 

provide preliminary data on the potential 

benefits of ink temperature controls to the 

gravure industry for further technology verification (see box on Study Limitations). The 

results are promising. 

•	 Small- and medium-sized printers in the 

product and packaging sector may be able 

to reduce solvent consumption, improve 

print quality, and achieve cost reductions 

by implementing ink temperature controls. 

•	 Decreasing solvent consumption and solvent emissions could also reduce health 

risks because of reductions in potential 

exposures to workers or the public. 

•	 The greatest benefits may occur when ink 

temperature is maintained near a typical 

room temperature rather than chilled to 

below typical room temperatures, suggesting less chilling is needed to achieve optimal results. 

•	 Ink temperature controls might also reduce 

overall ink consumption (up to 20%-30%) 

without adversely affecting print quality, but these 

results need to be confirmed on different substrates 

and in “real world” settings. 

•	 Ink temperature controls can also be expected to 

reduce solvent use (perhaps up to 50%), especially in 

the summer months when ambient temperatures are 

higher. 

Potential Cost Savings—Potential savings were estimated for two scenarios using the assumptions of the model 

facility (see box at right) and the solvent and ink consumption results from the WMU study. Scenario 1 

assumes a small printer operates at 92oF for three 

months and 79oF for nine months a year. Scenario 2 

assumes the printer implements temperature controls to 

maintain a constant temperature of 79oF all year. 

Conditions will vary greatly by facility; many other 

factors may also affect these estimates. Nonetheless, they 

provide a starting point for companies to estimate their 

• The study evaluated the effects of ink temperature on Type C inks only. Results 

may differ with other ink types. 

• The range of test temperatures (66oF to 92oF) was selected to represent the 

extreme of printing conditions that might be encountered in the industry. Smaller 

printers may have ink temperatures approaching the upper limit in the summer 

months, but these higher temperatures are not typical of year-round operating 

practices. 

• Many ink and solvent systems used in packaging and product gravure have an 

affinity for pressroom air moisture, particularly at low temperatures. Moisture 

pickup due to low ink temperature can cause blushing and ink kick-out. The 

study did not directly assess the moisture pickup of the colder inks, but no blushing and ink kick-out effects were seen. 

Potential Cost Savings 

Parameter Scenario 1 

Solvent emissions (lb/yr) 113,400 

Ink consumption (lb/yr) 97,200 

Scenario 2	 Reductions 

or savings 

86,400 27,000 

86,400 10,800 

Annual solvent costs $56,700 $43,200 $13,500 

Annual ink costs $388,800 $345,600 $43,200 

Solvent & ink costs $445,500 $388,800 $56,700 

Example Model Facility 

Press size: 23" wide 

Printing units: 3 

Annual operation time: 7200 hr/yr 

Press speed: 300 ft/min 

Solvent use rate: 9 lb/hr at 92oF 

(per color): 4 lb/hr at 79oF 

Ink use rate: 6 lb/hr at 92oF 

(per color): 4 lb/hr at 79oF 

Solvent cost: $0.50/lb 

Ink cost: $4.00/lb 

own potential savings. Although these estimates do not 

account for the cost of cooling, any cooling solution and 

associated energy requirements that cost less than the 

estimated savings above could result in payback after the 

first year. 

Industry Challenge—The results of the DfE Gravure 

Partnership suggest ink temperature controls may present 

5 
gravure printers with an excellent opportunity to prevent 

pollution at the source, while improving print quality 

and reducing costs. Small- and medium-sized printers 

that experience printing inefficiencies due to fluctuations 

in ink temperatures may benefit most from ink temperature controls, but no clear or commonly implemented 

solutions for addressing these inefficiencies yet exist. The 

DfE Gravure Partnership challenges the industry to confirm project findings to optimize printing operations. To 

meet this challenge, gravure printers could: 

•	 Independently evaluate the effects of ink temperature 

on solvent and ink consumption, print quality and 

cost. 

•	 Assess and/or optimize current ink temperature control options, including 

- Submerged copper coils in the ink sump, including 

the cost and pollution implications of frequent 

cleaning. 

- In-line heat exchangers on the supply line. 

- Room temperature control (air conditioning). 

•	 Adapt a temperature control option from another
 

industry.
 

•	 Develop a new, innovative method for controlling ink 

temperatures. 

What is EPA's Design for the Environment 

Program? 

EPA's Design for the Environment (DfE) Program partners with stakeholders to help businesses help the environment. DfE projects help 

businesses design products, processes, and management systems 

that are cost-effective, cleaner, and safer for workers and the public. 

The DfE goals are to: 

• Encourage businesses to incorporate environmental information 

into their decision criteria. 

• Effect behavior change to facilitate continuous environmental 

improvement. 

To accomplish these goals, DfE and its partners use several 

approaches including cleaner technology and life-cycle assessments, 

environmental management systems, formulation improvement, best 

practices, and green supply chain initiatives. 

To date, the DfE Program has brought environmental leadership to 

over 2 million workers at over 170,000 facilities. Small- and medium-sized businesses recognize DfE as a unique source of reliable 

environmental (as well as performance and cost) information that 

allows them to make better decisions. 

Questions to consider when evaluating the use of 

temperature control in a printing facility include: 

•	 How will less solvent consumption affect treatment 

systems such as oxidizers and recovery systems? 

•	 What is the cost of adding temperature controls on 

press and providing cooling water? 

•	 How do different colors and ink types behave, noting 

that in this study the two Type C inks behaved differently? 

References 

Celio, Tino (1998). Ink Temperature Control in Gravure 

Printing. Ambril, Swtizerland: Paper presented at the 

annual meeting of the Gravure Association of 

America conference, Memphis, TN. 

GAA (1991). Tone Reproduction. Gravure, Rochester, NY. 

Sosa, Rodrigo (1999). Effects of Temperature Control on 

Gravure Packaging Ink: A Thesis Submitted to the 

Faculty of the Graduate College in partial fulfillment 

of the requirements for the Degree of Paper and 

Imaging Science, Western Michigan University, 

Kalamazoo, MI. 

How Can I Get More Information? 

To learn more about EPA's DfE Program or the Gravure Partnership, 

contact: 

EPA’s DfE Program 

Phone: 202-260-1678 

Web site: www. epa.gov/dfe 

The Gravure Association of America 

Phone: 716-436-2150 

Fax: 716-436-7689 

UT Center for Clean Products and Clean Technologies 

Phone: 865-974-9526 

E-mail: socolofml@utk.edu 

Rodrigo Sosa, RJR Packaging (formerly of WMU) 

Phone: 336-741-4974 

E-mail: sosar@rjrt.com