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People’s biggest misconception about color management is that prepress is the only important area. The fact is, no matter how good your prepress work is, without a stable pressroom situation your color management program will be doomed to ongoing frustration as uncontrolled onpress variation turns your finely-tuned, color-managed prepress work into mush. Process control throughout all parts of the workflow is the foundation for a sound and stable color management program. Process control is all about reducing problems by eliminating or controlling variables. Most programs almost exclusively emphasize characterizing and controlling electronic prepress and output devices. That’s understandable given the importance of electronic devices in printing today. Without these devices working together successfully, getting predictable results is a hit or miss proposition. But in all the emphasis on prepress, a crucial part of successful color management frequently gets short shrift: controlling onpress variables that result from the complex interactions of the ever-expanding range of papers and substrates, plates and press chemicals. Printers often run into unexpected problems because they fail to take into account the complexity of these interactions. It’s not uncommon today for a printer to run dozens of sheets on a variety of presses, using several plate types and inks. To accommodate them all, printers may also use several fountain solution concentrates. The result can be a mind-boggling number of possible problems that adversely affect print quality, downtime and waste and reduce efficiency and profit. Controlling ink/water balance is among the most important issues for most printers, especially if you’re printing on synthetics and plastics. Ink/water balance is the heart and soul of print characteristics data which affects how the job will look. A few key examples: solid ink densities, tone value increase (dot gain), print contrast, ink trap and color purity (L*a*b or hue error and grayness). One effective way to solve water/ink variability problems is to reduce the number of fountain solution formulations you use. Selecting the right solution or solutions greatly simplifies the job. Repeatability or consistency in fountain solution formulation on press is crucially important in reducing variation, but many printers aren’t very precise in the way they mix concentrates and water. Fountain solution systems are available which lock in precisely-metered proportions of concentrates and water, enabling them to adjust to specific needs and problems, and producing virtually identical solutions time after time. Reducing the number of fountain solutions you use to a manageable number requires that you test and record the interactions of specific fountain solutions with every stock, ink and type of plate your shop runs, and characterize their interactions. Your press chemistry supplier should help you find the best way to do the testing. There aren’t any shortcuts or silver bullets to achieve effective color management. To be successful, you must include process control in the pressroom as a critically important part of your program. Nobody said color management was easy; but developing a successful program for reducing onpress variables usually pays for the aggravation in a relatively short time. By: Bruce Lanzerotti
by Dennis E. Mason In his hit tune, country singer Waylon Jennings sings about Looking for Love. He observes his searches in singles bars were to no avail, finally realizing that he has been “looking in all the wrong places.” Printers often concentrate their technology searches in the prepress area and in the features offered in the most modern presses. And while these are not “all the wrong places,” confining technology investigations to just those areas may mean missing some valuable opportunities to modernize your plant. A case in point involves the seemingly low-technology area of fountain solutions. As every press operator knows, maintaining proper ink-water balance is a critical factor in maintaining good, consistent color on the press. But a number of other variables interact with ink and water on the press to disrupt the balance. Changing papers (or synthetics, or plastics) and inks brings the system out of balance. Different presses even respond differently to the same ink, water, and substrate combinations. Fountain solutions consist of wetting agents and desensitizers in a fixed relationship. Achieving balance in the pressroom environment means fixing the proportion of these elements to conform to the press, the paper, and the ink being used. But any change in paper or ink means that the ratio of these two elements may need to be changed to bring everything back into equilibrium. Even moving a job to a seemingly identical press may necessitate making changes. An all too typical response to changes on the press is to add fountain solution, but printers find that this increases drying time and may not solve the core problem. A new fountain solution system on the market addresses the matter of maintaining the proper balance in a way so unique that it recently was awarded U.S. Patent 7,114,443. The new system is called Concept 21® and is available from RBP Chemical Technology. Key to the system is that it permits printers to precisely meter and blend unique and specific fountain solution formulations for each different situation that may be encountered. The balance can be changed on press by making a few simple adjustments, rather than by bringing in a new drum or tote of chemicals. Printers who use different solutions from several suppliers can replicate their preferred mixtures using just the two basic components and the Concept 21® device. The technology used in the Concept 21® blender is similar to that used in the food and pharmaceutical industries to ensure precision and consistency from batch to batch. Once the proper formulation is determined, it is dialed into the device and inadvertent changes to the balance cannot occur. But the formulation can be easily adjusted to meet the needs of different presses or different print jobs. Printers who bring precision to their fountain solution report better control of piling, faster makereadies, getting to color faster, consistently sharper dots, fewer web breaks, reduced chemical consumption, and reduced paper waste. Other advantages include reduced ink consumption and fewer washups requiring less press wash. Moreover, tests indicate that fountain solutions from the RBP Concept 21® system typically contain a minimum of 30% fewer VOCs than those made using ordinary solution concentrates, making them more environmentally friendly. Effective color management in the modern pressroom involves fingerprinting the press and controlling the process from end to end. But seemingly inconsequential elements of the process can bring the entire process to grief. Jennings' song mentioned looking for love in all the wrong places. Printers should look for technology in all the places. Reprinted with permission from the PIA/GATF 2007 Forecast: Technology, Trends, Tactics. Copyright 2007 by the Printing Industries of America/Graphic Arts Technical Foundation (www.gain.net). All rights reserved.
Match Your Press With The Right RBP Fountain Concentrate The following recommendations are based on current data and research, but may not work in all situations. For more information or additional recommendations call our technical service team at 800-558-0747. Web Product Recommendation Chart
* UNITROL - One-step Sheetfed Product Recommendation Chart
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Facts About Fountain Concentrates In lithographic offset printing it is necessary to keep the non-image areas of a plate moistened with water so that they will not accept ink. During platemaking these non-image areas are desensitized, usually with a thin absorbed film of gum Arabic and desensitizer so that they prefer water instead of ink. If the desensitized film was able to remain on a plate indefinitely, it would be possible to run plates with nothing but water in the dampening system. However, the desensitized film wears off gradually as the plate continues to run on the press. Eventually it is necessary to use chemicals to rebuild the desensitized film and keep the non-image area free of ink. The fountain concentrate is a mixture of chemicals and water that serves to repel ink from the non-image area of the printing plate. The function of the chemicals is to enhance the performance of the water, which serves to keep the non-image areas water loving and prevents corrosion (desensitizing) of the plate surface. Fountain concentrates are multi-component solutions. They usually contain a variety of chemical families. They include wetting agents such as surfactants and/or solvents. This family of chemicals acts to lower the surface tension of water and make it spread more efficiently across the plate surface. Fountain concentrates also contain film formers. In many cases the film former is Gum Arabic, but in the last 15-20 years some manufacturers have switched to synthetic polymers. The third major family of chemicals is acids and/or salts of acids. These chemicals act as buffering agents and desensitizers to adjust the pH of the press solution. They also condition the metal surface of the plate and prevent sensitivity and scratches from printing. The combination of these chemicals provides an environment that keeps the plate printing clean, while maintaining good ink and water balance. Fountain concentrates vary widely to meet an assortment of applications. Different plate materials such as paper, plastic, bi-metal and aluminum require different chemistries. The type of printing, ink, paper, water and dampening system also play a role in the type of fountain solution to be used. pH pH is a measure of the degree of acidity or alkalinity in a solution. pH is based on a logarithmic scale that runs from 0 to 14 with 7 being neutral. For each change of 1 pH unit the acidity or alkalinity changes by 10. For example, a change in pH from 7 to 6 would result in 10 times more acid, 7 to 5 100 times more acid and 7 to 4 1000 times more acid. Thus, it can be seen that small changes in pH represent dramatic changes in acidity or alkalinity. It is recommended that the proper operating range for pH in an acidic fountain solution is 4.0 to 5.0. If the pH becomes too acidic, the solution will start dissolving the aluminum oxide non-image area. If the pH is towards the neutral or alkaline side, the desensitizers such as gum Arabic will stop working properly. With the advent of conductivity as a control device for concentration of the fountain solution, pH is not being monitored as often as it should be. We recommend that both pH and conductivity be monitored to maintain print quality.
Conductivity Conductivity is a measure of the ability of a substance or solution to conduct an electrical charge. In water or any solution the degree of conductivity is determined by the amount of minerals and other ions present. Conductivity is measured on a linear scale, which is represented by the inverse of resistance. The units of measure are micromhos. When considering fountain solutions, most conductivities fall in the 1000 to 3000 micromhos range. There are several variables that influence conductivity. Organic solvents such as isopropyl alcohol will reduce the actual conductivity reading. A 25 to 30 percent isopropyl alcohol solution can cut the conductivity in half. Temperature also influences conductivity. As the temperature goes up, the conductivity goes up, as temperature decreases, so does the conductivity. A good rule of thumb, is for every 10° F change in temperature, conductivity will change by 100 micromhos.
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Alcohol replacers were developed and generally accepted into use in the 1970's as a replacement for isopropyl alcohol in the press ready mixture. Alcohol replacers, like isopropyl alcohol, are used in combination with a fountain concentrate to deliver a very thin and even water film across the plate surface on continuous type dampening systems. Many printers choose to eliminate the major disadvantages of isopropyl alcohol, including its health and environmental concerns, the increased cost of constant replenishment and its flammability. Alcohol replacers are basically composed of solvents such a glycol ethers and surfactants. They are normally used at 1/5 to 1/10 the level of alcohol which correlates to approximate levels of 1 to 5 ounces/gallon depending on type of press, dampening system and numerous other variables. Some key areas to look at when eliminating alcohol are: 1. Roller Hardness (i.e. durometer): Isopropyl alcohol will remove the plasticizers from the rubber, causing the rubber to harden. The harder a roller is, the less its ability to evenly carry a liquid. The durometer of the roller should be in the low 20's when going off of alcohol. One caution about alcohol replacers is that some products will cause the roller to swell. 2. Grindlines: During manufacturing, rubber and chrome rollers are cut down to specific diameters. During this process, lines are created on the roller's surface. Many times isopropyl alcohol will "bridge" these lines whereas alcohol replacers may not but will require rollers to be polished and/or desensitized. Roller settings may need to be adjusted or in some cases the rollers may need replacement. 3. Inks: Over the years inks have been formulated to work with alcohol. To ensure a smooth transition to alcohol replacers an ink may have to be reformulated. It is important that ink and fountain solution suppliers work together for optimum performance. 4. Press Condition: Older presses may have more mechanical problems such as roller bounce and vibration. Alcohol helped cover up these problems and complete elimination may be difficult in some cases. Current alcohol replacers have come a long way in eliminating alcohol from the pressroom. The conversion from alcohol to alcohol replacers must be accepted and committed to by press operators and supervisors if the change is to be successful. RBP AQUANOL® VS. ISOPROPYL ALCOHOL (IPA) The following information documents the relative safety of using our AQUANOL products containing 75% 2-butoxyethanol (EB) versus isopropyl alcohol (IPA) in press fountain solutions. Please keep in mind we refer to the working fountain solution because this is the solution that is in question; not the concentrated material in its container, but the diluted version. To understand the comparison, one must consider relative concentrations, vapor pressures, boiling points, flash points and physical hazards. A. Concentration of EB vs. IPA Typically in one gallon (128 ounces) working fountain solution four (4) ounces of AQUANOL would be added. The final concentration of EB in this working solution would be 2.3%. If IPA were used in place of AQUANOL, then in one gallon of working fountain solution there would be an average of 25 ounces IPA added to reach a concentration of 20%. Therefore, the concentration of IPA would be approximately nine (9) times more than EB. B. Relative Vapor Pressure and Boiling Point of EB and IPA
Volatility is a function of vapor pressure and boiling point. The more volatile a substance, the higher its vapor pressure, and the lower its boiling point. Consequently, IPA is far more volatile than EB. As a result, the pressroom will fill up with IPA vapor quite readily because IPA is used in a large concentration compared to EB, IPA has a lower boiling point compared to EB, and IPA has a much higher vapor pressure than EB. Also as the temperature in the pressroom increases so does the amount of IPA vapor in the air. Due to its low vapor pressure, high boiling point and low concentration, EB would not be a hazard to anyone when used in the prescribed amounts. Due to the physical properties of IPA, as stated in the previous paragraph, the working fountain solution would have to be replenished quite regularly with IPA due to evaporation loss. C. Flash Points
of EB vs. IPA D. Hazards of of
EB vs. IPA EB is a known skin irritant, and presents a significant health hazard when used as a concentrate. Safety precautions should be used when dispensing either of these materials. We at RBP Chemical Corporation are proud of the high quality of products. We are concerned with the welfare of our customers and strongly feel that the use of our AQUANOL® products does not present a hazard when used in prescribed quantities, label directions followed and handled by properly trained personnel. BACK TO TOP | EMAIL US | PRODUCT DATA | DISTRIBUTORS | NEWS Gum is applied to the plate surface in order to protect the background or non-image areas from oxidation, fingerprints, dirt and general sensitivity. The gumming process also helps desensitize the non-image area and render it more water-loving. There are several different types of gums used in the graphic arts industry, with some being more popular than others. All of them, however, have specific purposes as well as the aforementioned characteristics. Following is an explanation of four of these gums: Gum
Arabic In the pre-press area, Gum Arabic is normally used in the 8 Baumé range. It is used for short-term storage of the plate after development and before the press run. It can only be used for short term storage (one to two days) because, if left on the plate too long, the gum crystallizes and adheres to the entire plate surface. This will render the plate non-ink receptive, or gum blind. To remove Gum Arabic that has been on a plate too long, use hot water or additional gum. Gum Arabic is water soluble and serves as a good background desensitizer. In the pressroom, Gum Arabic is used as an additive to the fountain solution when better desensitizing of the plates' background is required. Normally used in a 14 Baumé mode, an ounce or more is added to the working fountain solution to aid in keeping the plate clean and free of oxidation. When honing a spot off a plate, Gum Arabic can be used to desensitize the area before restart. Litho
Gum Asphaltum
Gum Synthetic
Gum BACK TO TOP | EMAIL US | PRODUCT DATA | DISTRIBUTORS | NEWS Plate Cleaners - Are they all created equal? Is there more to the average plate cleaner than meets the eye? Is there one plate cleaner that can act as a quick fix and solve press and plate cleaning needs? Why don't plate cleaners work the same all the time? These are some of the questions that RBP technical service reps hear regularly. The following article will try to address them and help take the mystery out of choosing the proper plate cleaner for the job. MAKE A GOOD MATCH With most specialty chemicals, a good match between product and problem usually leads to greater success. Plate cleaners are no exception, as in most cases; specific plates demand the use of different cleaners. While some plates can stand up to just about any kind of plate cleaner, surface plates, which comprise a major portion of plates currently used, typically require a specific cleaner. A general rule of thumb is to use acid cleaners with unbaked digital aqueous and unbaked positive plates and alkaline cleaners with solvent and baked positive and digital plates. Alkaline cleaners are extremely effective at removing background tinting and scumming and do an excellent job of desensitizing the non-image area. Because solvent and baked positive plates can withstand alkaline cleaners, it is a good choice for them. However, using an alkaline cleaner on the photopolymer image area of an aqueous plate or unbaked positive plate can cause a loss of image or blinding. In all cases, follow plate manufacturers' recommendations or ask your chemical supplier to perform a capability test to determine the appropriate cleaner to meet your needs. A GOOD PLATE CLEANER CAN HELP SAVE MONEY Many press operators do not fully appreciate or value how a good plate cleaner can reduce downtime, new plate costs and wasted paper, while also improving print quality. A common occurrence in the pressroom is that an operator will begin to have trouble controlling the ink/water balance, see plugging and the deterioration of print quality. He cleans the plate, but the same problems resurface quickly so a new plate is ordered and installed. In this process there has been lost time, at least15 minutes for plate replacement, wasted paper and the cost of a new plate. Many shops estimate the cost of a remake at more than $100 per plate, counting time and material. Many times, in instances such as this, a thorough two or three minute cleaning with a good quality, compatible plate cleaner could have resolved the problem and saved time and money. Problems can also arise when there is a plate change and compatibility of the new plates and the cleaner is not checked. This can cause press problems, poor print, quality, reduced productivity and a frustrated press operator. Paper waste is an hot issue today, especially on webs. A good plate cleaner can help insure quick, clean restarts, free from tinting or scumming. It can sometimes take up to 4000 signatures on a restart before they are useable. A proper cleaning can reduce this to less than 500. TIPS TO REMEMBER WHEN CHOOSING A PLATE CLEANER....
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History tells us that the best press washes are those that break down and remove ink quickly, evaporate fast, and are easy to use. History also tells us that these traditional washes typically contain 90% to 100% petroleum distillates (VOCs). Today's environmental climate and the issuance of increasingly stringent regulations are creating a situation where these traditional, high VOC washes are no longer acceptable. The current target for low VOC washes is that they contain less than 30% VOCs (by weight) which equates to approximately 2.5 lb./gal. VOCs. The obvious question this poses is how do we move from the efficient, but high VOC traditional washes to the more environmentally acceptable low VOC products? Unfortunately, none of these alternatives is perfect. The surfactants typically used to formulate emulsion-based washes, if not properly removed, can build up on rollers and blankets, causing poor ink transfer, stripping and emulsification. The vegetable oil washes often require a rinse step, leave a greasy residue and are slow to evaporate. With wash-ups sometimes taking place up to 15 times a day, this can have a substantial impact on production cost. The washes containing exempt solvents, while efficient and causing little productivity sacrifice on the part of the press operator, do carry potential health risks and some are considered ozone depleting. Attempting to go from a solvent based wash to a low VOC alternative overnight can cause problems and frustrations for the press operator. RBP advises that the practical and cost effective approach is to do the changeover in several steps. While reducing VOCs is critical, cost of restarts, paper and quality of printing must all be considered. First, choose a low VOC wash that is right for your application and is from a reputable manufacturer. Begin by using it as a roller wash, but include periodic deep cleanings using a wash such as RBP Color Change Wash Step 1 and 2 to eliminate surfactant build up. After a period of successful use, begin using the wash on blankets following manufactures' recommendations. For deeper cleaning a traditional wash can be used as needed. While this procedure does not completely eliminate all VOCs, it significantly reduces them. To date there are no perfect low VOC washes. But, with a strong commitment and understanding that these washes perform differently and require more attention, a pressroom can effectively eliminate a substantial percentage of VOCs from its press washes without sacrificing efficiency and print quality. HOW TO MAKE LOW VOC WASHES WORK... Making the transition to a low VOC wash does not have to cause undue sacrifice or frustration. In RBP's experience, the following steps can eliminate some of the problem areas and make the change successful. While this procedure does not completely eliminate VOCs, it significantly reduces them without sacrificing cost effectiveness and print quality.
RBP, like other chemical suppliers, continues to work toward developing higher performance, more effective low VOC washes. BACK TO TOP | EMAIL US | PRODUCT DATA | DISTRIBUTORS | NEWS Use
Acid Based Neutral Fountain As anyone in the newspaper business knows, printing good quality color is tough. Poor ink density, background toning and a washed out appearance are all common problems. However, advertisers and consumers alike continue to demand more and more color, challenging newspapers to improve their quality while still containing costs. Back in the days when newspapers were only black and white, inexpensive, alkaline based fountain concentrates did the job. But as color entered the picture and environmental regulations tightened, printers turned to neutral fountain concentrates to solve some of their problems. The neutral formulas for the most part are based off of alkaline fountain concentrate chemistry. The lower pH makes them more environmentally friendly and they do produce better quality color, although still not the strong, crisp color associated with an acid based fountain concentrate. To answer the call for even higher quality color, RBP Chemical offers acid based neutral fountain concentrates with pHs ranging from 6.0 to 7.0. These fountain concentrates consistently produce high ink density and truer colors, with fewer toning and emulsification problems. The slightly acidic base allows for lower water settings and better registration control as well as less biological growth. Call us today for more information 800-558-0747. BACK TO TOP | EMAIL US | PRODUCT DATA | DISTRIBUTORS | NEWS
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