Technical support

Print

• Uni Power Flush
• Uni O.D. Deglazer
• Uni Metering Roller Cleaner
• Uni Metering Roller Cleaner BD
• Uni Chrome Cleaner
• Uni Chrome Desensitizer

Print

WATER TANKS AND PANS

1. Empty holding tank for fountain solution and water trays.
   To be completed weekly.
2. Clean out water trays, thoroughly removing all deposits of paper by-products such as calcium and paper dust.
   To be completed monthly.
3. Flush water system with warm water and Uni Power Flush. Remember to turn off cooling unit on central tank when doing this in order not to damage the unit. Let circulate at least 30 minutes or longer if possible. Rinse once with water and another time with your normal mix of Unigraph chemistry.
   To be completed every three months.

ROLLER AND BLANKET MAINTENANCE

1. To be done as the FIRST major decontamination.
   Remove ink from ink rollers and blankets using your regular wash-up solution. Mix Uni O.D. Deglazer 70/30 with hot water (70% O.D. + 30% hot water) in a wash-up bottle. Apply the mix in the ink train. Engage the dampening system while doing the procedure in order to decontaminate the dampening form roller. Apply 8-10 ounces of mix to each unit continously. Let the mix run for 15-30 minutes then rinse off. Repeat if necessary.
2. For preventative maintenance
   Use 4-6 ounces of the 70/30 mix of Uni O.D. Deglazer and hot water, if possible, after every shift. If a job is continuing into another shift, try this procedure after the end of that shift.
   To be completed daily.
3. Overall maintenance program
   • Metering roller

     Use Uni Metering Roller Cleaner (code 334) or Uni Metering Roller Cleaner BD (biodegradable) (code 333) on the metering roller as part of the overall maintenance program.
     To be completed daily

   • Chrome rollers
     The chrome rollers in the dampening system also need to be cleaned and desensitized. Use Uni Chrome Cleaner to remove any ink left on the chrome roller. Once the chrome roller is clean, apply Uni Chrome Desensitizer. The longer it can stay on the roller, the more effective it will be. It can be left on overnight or over the weekend if the press is not running.

     To be completed daily. (Tip: Use before the beginning of your shift, if possible.)

   • Blankets

     The blankets should also be decontaminated at the same time as the rollers. Remove any excess ink from the blankets using your regular wash-up solution. Apply the Uni O.D. Deglazer, without water, to the blankets and leave the product on them for the time it takes to do the ink units. When possible, leave the Uni O.D. Deglazer on overnight. Remember to rinse off the residue with wash and water before starting up again or use the automatic roller and blanket wash system if you have it.
     To be completed weekly.

TECHNICAL INFORMATION

1. Always finish each application with your regular wash-up solution and the water (room temperature is fine). It is extremely important to remove any residue of Uni O.D. Deglazer and the contaminants left on the rollers and/or blankets.
2. Once the rollers have been decontaminated, you might have to reset the ink forms and dampener form. The decontamination process will revitalize the rollers and may slightly change the durometer of the rollers, therefore altering the settings. To ensure that all of the Uni. O.D. Deglazer is completely removed from the unit, you should ink up, wash up, and ink up again before starting the next job.
3. You can use the Uni O.D. Deglazer daily (end of shift, colour change) or weekly as preventative maintenance. A monthly application should be scheduled if you cannot do it daily or weekly.
4. Regular preventive maintenance is crucial to ensure ongoing production. Every time a piece of paper passes through the press, the contamination process starts. This is normal in the printing process, but because of the papers being alkaline, the effects of the contamination can show up more quickly and be more severe.

Print

Taking proper care of your inking and dampening rollers is extremely important as they are responsible for laying the ink down evenly and smoothly to the plate to give you the highest quality print. Unigraph has a full selection of high quality products to assist you in keeping your rollers in top condition.

Following are some guidelines for the care and maintenance of rollers.

A good roller should have a soft, velvety feel to it with a durometer between 25 and 32 (especially form rollers).

Once a roller has a durometer over 35, it no longer has the ability to lay the ink down smoothly and evenly and should be replaced.

Regular use of Uni O.D Deglazer will help keep the durometer of the rubber in the desirable range and increase the life of your rollers.

One of Unigraph’s water-miscible washes should be used for your regular wash-ups with water always being used toward the end to assure that the surfactants and other water-miscible particles are removed from the rollers.

Roller settings should be checked on a regular basis. A quick check each month would be advisable as it is normal for rollers to shrink somewhat during their usable life.

A good quality roller will shrink a little early in its lifespan, then very gradually change over the longer term.

Good quality, well maintained rollers can be expected to last two years or more.

Check press manufacturer’s recommendations for roller settings and in all cases keep the settings as light as possible as there is no positive side to a heavier setting.

Heavier settings will create more heat in the ink train and cause rollers to deteriorate quickly.

They can also cause deflection in the rollers which will give you an uneven stripe on the distributor roller and have the roller touching the plate in some areas and not others.

Colour inconsistency may also be experienced as the heavier settings may not allow the ink to flow evenly and consistently through the nip of the rollers.

Form rollers should be checked for side play as any sideways movement in the rollers can cause premature glazing as well as negative effects on print quality, some slurring of the dots and tinting or toning on the printed sheet.

Make sure that new form rollers are shimmed and fitted properly to prevent any sideways movement.

If form rollers are purposely allowed to move sideways from time to time to combat a ghosting problem, never allow the last form roller (usually #4) to oscillate as this is a clean-up roller. Also assure that the rollers are locked up properly again after the ghosting form is completed to prevent wear in the journals and glazing of the rollers.

Poorly maintained rollers are a major cause of poor print quality. Assure that this is not the case in your shop and make Unigraph products a part of your regular roller care.

Print

In the form of precipitated calcium carbonate or ground calcium carbonate, it is used as a filler in papers. The paper you print on is changing. Twenty years ago, almost all of the mills in North America produced paper using an acid process. By 1992, 20-30% of these mills were producing alkaline paper. In Europe, this figure is 50-60%. Alkaline paper making in North America is expected to grow during the next five years until 90% of these mills will be producing alkaline paper.

The move from acid paper toward alkaline paper is not an arbitrary one. Alkaline paper offers several advantages over acid paper:

• It is less polluting to our environment overall
• It lasts longer
• It has improved sheet strength
• It uses less trees per ton of paper
• It has a highter brightness level

For all the benefits, alkaline paper now creates a whole new set of printing parameters that printers must now face and learn to troubleshoot in order to produce quality results.

• Tinting on printed sheets
• Toning on the plate
• Blanket piling which produces a framing effect
• Build-up on non-image area of the plate weakening receptivity of water (scumming)
• Roller glazing
• Contamination of fountain solution
• Calcium carbonate leaches out of the paper and is deposited on the blanket. On the blanket it causes piling and picture framing.

From the blanket, calcium carbonate is transferred to the plate and now causes hickeys, toning and water is less receptive to the non-image area of the plate, which in turn, you start to scum. The ink and water forms pick up the calcium carbonate from the plate which causes rollers to glaze and harden.

As the run lengthens, calcium carbonate will find its way into the dampening system and contaminate the water, which will increase pH and conductivity.

Some calcium carbonate may leach out of the paper during the printing process. When this happens, the transparent calcium carbonate flakes, which have sizing particles attached to them, migrate to the upper form roller. Once there, they are milled into the ink and dispersed throughout the moisture system and the ink train.

The discovery of special alkaline-compatible sizing systems made the production of alkaline paper a reality. But once again, this key ingredient in alkaline paper causes some problems in the print process. As mentioned previously, when these calcium carbonate particles leach out of the paper, they have sizing bonded to them. Eventually, these calcium carbonate/sizing particles come into contact with the ink. These sizing compounds sometimes activate the ink driers prematurely, resulting in both ink feedback on metal-surfaced dampening rollers and a calcium glaze build-up on the blanket.

Conventional blanket and roller washes will not remove the build-up that results from the leaching of calcium carbonate/sizing particles. You must use water-miscible wash to remove this type of glaze. Leaving this glaze untreated is not an option – you will experience a noticeable decrease in print quality.

SOLUTION

Unigraph fountain solution product is designed to break these calcium carbonate/sizing bonds and keep them “tied up” (sequestered is the technical term) until they are removed during roller wash-up.

Print

WHAT ARE SILICONE PRODUCTS?

These products are high quality emulsions containing silicone and other chemicals emulsified with water which enable a variety of printing operations.

WHY DO WE USE THESE PRODUCTS?

These silicone emulsions assist and benefit a number of printing operations.

MAIN ADVANTAGES:

• Improves or eliminates scuffing and ink smearing during web printing process and storage operations.
• Reduces or eliminates static electricity produced during printing process.
• Improves wetting of application rollers for more even coating on the paper.
• Reduces or eliminates corrosion in metal parts of the press.
• Eliminates necessity to use additive chemicals as anti-stats etc…
• Very stable in concentrated and diluted form.
• Diluted solution dries much faster than standard silicone, making all operations faster and more efficient.
• Contains powerful preservatives, which protects solution from bacteria and fungi.
• More efficient than any pure silicone emulsions, therefore can be used in lower concentration.

WHY ARE DIFFERENT CONCENTRATIONS SUPPLIED?

Solutions with different solid concentrations are helpful when applied on different surfaces, finishing processors, and when presses are running at different speeds.

CAN YOU ADD EXTRA ANTI-STATIC?

All Unigraph silicone products contain high levels of anti-static additives. However, if required, some extra Unigraph anti-stat can be added, approx. 1 to 3 ounces per gallon of mixed solution.

HOW IMPORTANT IS A DOSAGE?

Accurate dosage is important for performance and economy. Excessive amounts of anti-stat or silicone product can be detrimental to the final performance. Unigraph recommends Dosatron Graphic D14MZ10 doser which offers the following benefits: Extremely accurate dosage between 1 – 10%, economical use of emulsion, non-electrical application, trouble and services free, easy installation.

DOES WATER SUPPLY MAKE A DIFFERENCE?

Soft water is preferred because it produces a stable solution, free from fluctuation of town water. Hard water can produce a surface scum which interferes with even film on applicator roller.

Print

Download PDF

Print

PILING

One definition of piling is a build-up of ink (or ink components) and paper linters, generally on the blanket. This is a major concern for web printers because of the waste generated each time that the blankets must be cleaned. As these materials build and the blanket thickness increases in local areas, print quality will deteriorate. You will generally see this build-up in the non-image area of the blanket, and it tends to be worse at the trailing edge of solids.

When piling becomes thicker, the trailing edge of the image will begin to lift off the blanket and stop printing. Piling is a very good indicator of fountain solution, ink, and paper compatibility. On good stock, the blankets may only require cleaning every 200,000 impressions. The image does not usually pile, because fresh ink is constantly being transferred from plate to blanket to paper. This constant transfer tends to prevent any significant accumulation of foreign material on the blanket.

There are several contributing factors that influence the rate of piling:

1. The amount of water being carried on the plate/blanket. Running too dry generally increases the rate of piling.
2. The “speed” of the inks. Inks formulated with faster oils may tend to dry out and pile rapidly.
3. The lubricating ability of the fountain solution.
4. The type of plate used (smooth grain plates usually pile less).
5. Paper surface-loose fiber may be pulled off and added to the accumulated ink resin.

LINTING

Linting is caused by stock with loose surface fibers or by excessive tack of the ink or blanket. Paper fibers are pulled off the sheet and then build-up on the blanket. “Release Agents” are often included in fountain solutions or alcohol substitutes to decrease the “tackiness” of the blanket surface and reduce the tendency to pull the fibers off the sheet. Typical non-piling additives are made from glycols that will tend to keep the blanket moist. Some printers will run paper that has loose surface fibers through a dummy unit before laying down the first color. Some of the loose surface fibers will be pulled off and stick on the dummy blanket reducing linting in subsequent units.

Print

WHAT IS ROLLER GLAZING?

Are you using the right deglazer to effectively remove calcium from your press? This may seem like an odd question to ask a pressman. A good brand-name deglazer should do the job, right? Not necessarily. With all the changes that have been made to the paper in the last 10 years, it is crucial to understand exactly what is happening on press and what a deglazer should be doing for you. Let’s breakdown what glaze is. Glaze can form and accumulate from 4 primary sources:

1. From the paper.
2. From the ink.
3. By-products from the fountain solution and/or an alcohol substitute.
4. Sealing gum and chemistry picked up from new plates.

A good deglazer should be able to clean what is water-soluble (sources 1, 3 and 4) and what is solvent soluble (source 2).

One of the biggest changes in our industry has been the introduction of alkaline-based paper to replace acid-based paper. There have been many reasons for the change (environmental issues in making the paper and brightness of the sheet) and there have been many issues printers have had to address because of it.

One of the most notorious problems has been the effect of calcium coming off the sheet and being introduced into the printing process. Here are some of the most common problems caused by calcium contamination.

• Plate blinding or ink walking off the plate (dot blowout)
• Premature plate wear
• Poor ink transfer down the ink train
• Inconsistent ink/water balance causing colour variation throughout the press run
• Reduced drying time
• Hardening of the rollers
• Pre-mature roller wear
• Picture framing on the blanket, especially running a short sheet
• Build-up on the impression cylinder

There is really no way of stopping calcium from coming off the paper. Let’s go through what actually happens as you start your press and paper passes through it.

1. Calcium (whiteners, chalk and fillers) leaves the surface of the sheet and is released onto a humid blanket.
2. From the blanket, it transfers to the plate and dissolves from a powder to a liquid because of the fountain solution on the plate.
3. At this point, the liquefied calcium touches the dampener form and ink form rollers.
4. On the dampening side, it transfers from the dampener form back onto the pan roller and into the tray and then back into the recirculation unit. For those of you without a recirculation unit, it sits in the tray and accumulates.
5. On the ink side, it touches the ink form rollers and starts to contaminate the rollers all the way up the ink train.
6. When the press is not running, the calcium in the rollers dries and then crystallizes.

What’s the end result of all this? You now have a glaze that is literally locked into the pores of your rubber rollers due to the crystallization of the calcium. How do you remove the contamination from your press and control it? Use O.D. Deglazer!

Print

DEALING WITH SCUMMING

Unigraph offers you a short and practical guide in helping circumvent one of the most common printing problems: scumming (greasing). Scumming occurs when non-image areas of the plate begin to accept ink. Do not confuse scumming with tinting, which is generally characterized by a light uniform ink film over the entire plate. There also exists simple procedures to distinguish between both problems. Increase the flow of fountain solution or hone the plate with a desensitizing stick while the press is stopped. At restart, if the problem diminishes or disappears, it’s most likely scumming. If your diagnosis leans toward scumming, we suggest a series of probable causes and associated remedies.

1. Scumming may arise due to inadequate dosage of fountain concentrate, alcohol or alcohol substitute:
   

   Cause	Remedy
   Not enough concentrate.	Check dosage, keep at recommended pH and conductivity.
   Too much concentrate.	Check dosage, keep at recommended pH and conductivity.
   Low alcohol or alcohol substitute.	Contact your fountain solution manufacturer.

2. Scumming may be ink related:
   

   Cause	Remedy
   Too much ink being carried and squashed over non-image areas.	Reduce ink feed or use a denser ink pigment.
   Ink is too soft and spreads over non-image areas.	Add heavy bonded varnish to ink.

3. Scumming may appear if insufficient dampening solution is transferred to the plate:
   

   Cause	Remedy
   Too little fountain solution.	Increase flow of fountain solution.
   High dampening temperature (low viscosity).	Ideally, should range between 10-15º C (50-60º F).
   Dirty, worn dampener sleeve or metering roller.	Clean or change devices.
   Improper dampening settings.	Reset dampeners to appropriate settings.
   Improper form roller settings.	Check and adjust stripe on plate.
   Improper roller durometer.	Measure and change to specifications.
   Improper plate/blanket packing.	Set according to instruction manual.
   Glazed blanket.	Clean all gum, ink and particulates.

4. Too quick evaporation of the thin water film on the plate may cause scumming:
   

   Cause	Remedy
   High dampening temperature.	Ideally, should range between 10-15º C (50-60º F).
   Air drafts blowing on the plate.	Prevent or shield from air drafts.

5. Scumming may also come from a faulty plate:
   

   Cause	Remedy
   Improper gumming.	Clean plate with water and/or cleaner conditioner.
   Plate not opening or not desensitized.	Gum plate on press.
   Sensitive or light-struck plate.	Desensitize plate, apply scratch remover or plate cleaner.
   Prepress problems: exposure or development.	Make new plate.

Going through this troubleshooting procedure may help you to identify the problem and the cause, thus leading to the appropriate action to take. Keep in mind that tinting, bleeding and plugging may leave an image similar to scumming, however, the causes could be essentially different.

Print

IT BEGINS WITH A MINIMUM OF INK, A MINIMUM OF WATER AND A FOUNTAIN SOLUTION WITH THE RIGHT SURFACE TENSION.

Lithography is really a very simple process. With great precision and at high speed, water and ink are metered to the plate simultaneously. They mix with each other in a meticulously-controlled way on the form rollers and are deposited separately, each to its own designated area on the plate.

Experienced press people know that the lithographic process relies on the equilibrium of the ink-water mixture. One of the most difficult variables to control is the ever-changing relationship between ink and water on the plate surface. To ensure minimal use of ink and water and to achieve the best possible ink-water balance during a press run, a fountain solution with a surface tension between 32 and 45 dynes/cm, according to the type of press used, is essential.

Besides the minimum ink-water balance, there’s a second important factor that contributes to the success of a good impression – the cleanliness of the non-image area of the plate.

A fountain solution containing a natural Arabic gum (14ºBe) ensures a continuous formation of a protective film that desensitizes the plate’s non-image. Maintaining precise control over the protective film will ensure minimal use of water and result in an optimal ink-water balance.

A GOOD FOUNTAIN SOLUTION IS CRUCIAL

Experienced press professionals understand this. They realize that a fountain solution’s surface tension always affects the printing process since it acts directly on the quality of the water that’s transported as well as the ink-water mixture. It facilitates the formation of a thin, uniform and reproduceable water film before each application of ink. These two key requirements (fast plate wetting and the ability to form a thin water film) are critical for lithographic dampening systems. And they are largely determined by the surface tension of the fountain solution.

Pure water has a surface tension of 72 dynes/cm. In dampening solutions containing an alcohol concentration of 10% – 25%, the surface tension will be reduced to 35 – 45 dynes/cm. This enables the solution to spread over the plate rapidly in a thin, continuous film.

In general, a fountain solution will consist of water, acid and gum (see above), corrosion inhibitors to prevent the solution from reacting with the plate, fungicide, anti-foaming agent to prevent build-up. Last but not least, we find wetting agents such as isoproponol or alcohol substitutes, which decrease the surface tension of water and water-based solutions.

When alcohol or these substitutes are mixed with a fountain solution on a press using a dampening system employing alcohol, the surface tension is reduced. The result: alcohol or its substitutes help the water to wet the dampener form roller evenly, requiring less dampening solution.

A thinner film of solution will help keep the non-image area of the plate clean. It will also help to spread water properly over the ink on the rubber bareback form rollers that apply both the ink train – therefore less dampening solution is applied to the paper. Thinner film also aids in preventing water spotting because the fountain has finer drops dispersed in the ink. It also suppresses foaming.

THE IMPORTANCE OF ALCOHOL AND SUBSTITUTES

The addition of alcohol in the fountain solution increases the viscosity of the water, which in turn allows a thicker layer of dampening solution to be applied to the ink and non-image area and improves the performance of the ink, paper and printing plates.

When using substitutes, the fountain solution is metered by the squeezed rolls used in the majority of continuous contact-type dampeners. The immediate effect is that the dampener speed must be turned up, which leads many press operators to conclude, erroneously, that they must use more water to print with a substitute.

To partially offset the loss in the viscosity produced by eliminating alcohol, the dampening solution can be cooled to 50 – 55ºF. Substitutes differ from alcohol in several key properties – how they affect viscosity, surface tension, pH and conductivity.

In alcohol-free dampening solutions, surface tension is reduced by additives called surfactants. These are organic chemicals that concentrate at interfaces because of their polar molecular structures. They travel to the interfaces between the dampening solutions, and both air and the ink on the image areas of the plate. At higher press speeds, interfaces are used and reformed rapidly. Surfacants may diffuse rapidly to replenish new interfaces. An excess of surfactants can contribute to excessive ink emulsification.

Alcohol substitutes also offer an excellent opportunity to dramatically cut the amount of VOC emissions from a press. Because alcohol substitutes do not have a diluting effect on ink when used in proper concentrations, less ink and water are needed for good colour reproduction. Sharper dots are produced and there is less of a tendency for dot gain.

Print

VOCs (Volatile Organic Compounds) are unhealthy for many reasons – they can also harm the environment by helping form smog, which damages crops and forests in addition to being harmful to lungs.  Some blanket washes also contain chemicals called Hazardous Air Pollutants (HAP’s), which may also harm human health and the environment.

By using blanket washes containing fewer VOC’s, you can significantly reduce the impact that your printing operations have on employee health and the environment. You may also be able to reduce your regulatory requirements. To find out the VOC content and other components of your current blanket wash, ask your supplier and check the product’s Material Safety Data Sheets ( MSDS ). Suppliers can recommend substitutes containing less VOC’s.

PRESS WASHES?: SOLVING THE DILEMMA

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 ( VOC’s ).

Today’s environmental climate and the issuing 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 % VOC’s ( by weight ) which equates to approximately 2.5 lbs. per gallon.

The obvious question is how do we move from efficient, high-VOC traditional washes to the more Environmentally acceptable low-VOC products ?

Unfortunately, none of the alternatives are 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 also slow to evaporate. With wash-ups sometimes taking place up to 15 times a day, this can have a substantial impact on production costs. Include periodic deep cleanings using a wash such as Unigraph’s Color Change Wash Step1 and 2 to eliminate surfactant build up.

Washes containing exempt solvents are efficient and sacrifice little in productivity, but they present problems and frustrations for the press operator. If you attempt to go from a solvent-based wash to a low-VOC alternative overnight, the most practical and cost-effective approach is to do the changeover in several steps. While reducing VOC’s is critical, cost of restarts, paper and quality of printing must all be considered.

HOW TO MAKE LOW VOC WASHES WORK

Making the transition to a low-VOC wash doesn’t have to cause undue sacrifice or frustration. The following steps can eliminate some of the problem areas and make the changeover successful. While this procedure doesn’t completely eliminate VOCs, it significantly reduces them without sacrificing cost effectiveness and print quality.

Choose a good quality, low-VOC wash from a reputable manufacturer.

Begin using on rollers. Periodically deep clean them with a traditional two-step color change wash to eliminate surfactant build-up.

After a period of successful use on rollers, begin using as a blanket wash, always following the manufacturer’s recommended procedures. In cases of unusually difficult cleaning, a traditional wash should be used.

To help avoid problems, continually monitor rollers and blankets. Look for signs of surfactant build-up, such as greasy residue, ink emulsification, poor ink transfer or slow cleanup.

While this procedure does not completely eliminate all VOC’s, 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 VOC’s from its press washes without sacrificing efficiency and print quality.

The development of higher-performance, more effective low-VOC washes is always continuing – find out which one is right for your shop.