Read CIM_VioletPrint_A4_May2006_v5.indd text version

DIGITAL PLATES

­

VIOLET

Violet Print

digital plates

Customer Information Manual

Version 1

European Technical Applications Group May 2006

Table of Contents

Introduction Storage, Handling and Loading into Platesetters Prepress Working Environment Chemistry Health & Safety Processing Processor Care Baking Parameters Platesetter Exposure and Linearisation Set-Up Press Troubleshooting ­ Plate/Platesetter/Processor Troubleshooting ­ Press 1 1 3 4 4 5 9 10 10 12 13 17

Kodak Violet Print digital plates CIM/ETAG May 2006

Introduction

This document has been issued by the European Technical Applications Group for all Kodak customers using Kodak Violet Print digital plates. The document is designed to enable the Violet Print plate customer to obtain optimum performance through recommended guidelines and best practice operational procedures. This Customer Information Manual for Violet Print plates is functional for all markets supplied by the European region of Kodak. This includes Europe, Africa and the Middle East Region (EAMER) and the Greater Asia Region (GCR and INSEAN). Compared to conventional workflow, Computer-To-Plate (CTP) workflow requires a higher level of control, maintenance and cleanliness to maintain a consistent and reliable prepress and print process. Kodak does not accept any liability for the misuse of their products.

Storage, Handling and Loading into Platesetters

Storage

Unopened packs of plates must be stored flat on a secure level surface, away from excessive cold, heat, humidity and direct sunlight. The ideal storage conditions are 15°C ­ 25°C and 40 ­ 70% humidity. For manual loading platesetters, the plates should be stored flat in their packets with plates removed from one open end of the packet. The shelf life of Violet Print plates is 12 months under recommended storage conditions. See expiration date on packet.

Plates must be stored flat on a secure level surface, away from excessive cold, heat, humidity and direct sunlight.

Storing the packet of plates against a wall will create a bend in the plate and may prevent it from being loaded into the platesetter.

Storing plates vertically in their cardboard outer casing could allow the plate packet inside to become unattached to the outer casing and drop, thereby causing damage to plate edges and corners.

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 1

Stacking Plate Pallets

Single packs: Max. 2 pallets, same size Bulk boxes: Max. 2 pallets, same size

Container: Max. 4 pallets, same size

Handling

When plates are being carried in either their outer casings or paper packaging, the plates must be carried vertically to avoid bending or kinking. The outer packaging can look undamaged, but the plates inside can become kinked if proper handling procedures are not carried out.

Plates must be carried vertically when in their packaging.

Plates carried with any kind of bend may distort the plates and aect the loading and punching of the plate in the platesetter.

Picking up and carrying plates with the strapping will also bend and kink the plates. The strapping may also incur edge damage on the plates.

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 2

Loading into Platesetters

The punching and loading of plates in any platesetter is a critical process. Damage to the plate edges, and introducing edge wave by poor handling of the product, will incur platesetter errors in loading, registration and imaging of the plate. In most cases this will cause the plate to be rejected by the platesetter. Additionally, out of focus situations can be caused by dirt, debris or any foreign body on the platesetter drum or on the back of a plate.

When loading plates of sizes 1030 mm and larger, two people should carry the plates from the packaging to the platesetter cassette, (Fig 1).

Fig. 1 Correct loading of the cassette

It is not possible for one person to load a full packet of plates and keep the plates flat due to the weight, (Fig. 2).

Fig. 2 Incorrect loading of the cassette

If only one person is available, split the pack and load a few plates at a time to maintain flatness and prevent kinking.

Prepress Working Environment

Use Violet Print plates in a controlled environment of 21°C - 24°C. Plate speed is aected outside these limits. When taking a pack of plates from a storeroom, allow sucient time for the plates to equilibrate in the platesetter room. 40% - 60% relative humidity (RH) is required. Plate speed and latent image stability are aected above these limits. Low RH can aect the de-interleaving performance in autoloading platesetters. For manual operations, Kodak Violet Print plates must be handled under EncapSulite G10 safelights with lighting levels between 100 lux and 200 lux. Tolerance to G10 safelight is 1500 lux min (e.g. 15 minutes at 100 lux). Kodak Violet Print plates have no tolerance to white light. The maximum time allowed between completion of exposure and processing is 10-15 minutes under the specified platemaking room conditions. Opened plate packs should be stored horizontally in their packaging, ensuring that the pack is light-proof. Store re-sealed packs between 21°C - 24°C and 40% - 60% relative humidity, and use the remaining plates as quickly as possible within 2 - 4 weeks.

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 3

Chemistry

Recommended storage conditions for un-opened developer and replenisher containers are 5°C to 27°C. Store in a dry area away from bright sunlight. The shelf life of un-opened developer and replenisher is 24 months. When in use, an opened container of replenisher will start to absorb carbon dioxide from the atmosphere and the pH will fall. Replace with a fresh container after 2 weeks in use. When filling the developer tank of the processor, it is likely that a part-used container of developer will be left. If the part-used container is less than 1/3rd full, discard as waste. If the part-used container is more than 1/3rd full, re-seal the container for later use.

Accredited Kodak Chemistry

Violet Print digital plates Developer Finisher Kodak Violet 500 developer and Violet 550R replenisher Kodak 850S plate finisher Kodak deletion fluid 231 (EAMER, Hong Kong, Southeast Asia) Deletions Kodak deletion pen C41 / C42 (EAMER, Australia) Kodak deletion pen C61 / C62 (This deletion pen gives better results if the imaged plate has been left some time before going to press.) Additions Plate cleaner Kodak addition pen P21 / P22 (EAMER, Australia) Kodak Tone-Up cleaner (EAMER), or other mild plate cleaners, can be used sparingly. Kodak Universal plate cleaner (Greater Asia Region)

Health & Safety

When handling Kodak products, read the Material Safety Data Sheet for health hazard data, precautionary information and suggested first aid. Contact your Kodak representative for MSDS copies, or click on the "Service" tab on the Kodak web site (www.graphics.kodak.com) to find relevant environmental and MSDS information.

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 4

Processing

Quick Set-Up Checklist

Before the installation, ensure that all chemistry and equipment is accredited for use with the Kodak Violet Print digital plate. a) Ensure that the brush and roller pressures are correct and are appropriate for the plate gauges being used. It is important to set the brushes in the developer section correctly to give even development and smooth transport. The same brush pressure settings should be used for all gauges of plate being used. See Additional Notes. b) Set transport speed to give the correct developer dip-to-nip time of 19 to 21 seconds. Check the dip-to-nip time to be certain of the correct developer time. c) Set the correct preheat temperature to give the target Thermax strip reading of 110°C - 116°C. (Thermax strip readings of 104°C - 116°C are allowed on processors where the preheat uniformity is not good, but this may give a little more variability in high screen ruling flat tints). Check the preheat for each gauge of plate used. Processors with hot-air preheat should be able to give correct plate temperatures for each gauge at the same panel setting. For those processors with IR ceramic tiles, dierent settings will be required for each gauge. With IR ceramic tiles allow 10 to 15 minutes when changing gauges for the preheat to re-equilibrate. See Additional Notes. d) Make sure that the chiller system is functioning properly. e) Set the developer temperature to 23°C.

Illustration of Thermax strip reading 110°C

f) Set the developer system replenishment regime which is appropriate for the processor being used. Check the replenisher pump calibration. The recommended procedure to set the calibration is to measure the volume of replenisher that is delivered into a graduated vessel. g) It is important that the pH of the developer is maintained to ±0.3 pH units relative to fresh developer. See Additional Notes. h) Ensure the drains and plumbing are configured correctly. Any discharges to drain must comply with local regulations. i) If necessary, correctly position all spray bars. j) Ensure that all other processing parameters have been set correctly.

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 5

Additional Notes

Setting Brush Pressures Several methods are available for determining optimum brush pressures in the prewash, developer and rinse sections of the processor. Set the prewash and rinse brushes to medium pressure. Set the developer brushes to a medium to hard brush pressure evenly across the width of the plate. Do not over-tighten the brushes as this will damage the brushes and provide no benefit. Over-tightening the brushes can result in plate bending or crashing. It should be possible to achieve uniform development for dierent plate gauges at one setting of developer brush pressure.

Preheat Setting The preheat value on the processor has to be set to give the required preheat plate temperature. Adhesive temperature step wedges are used. The recommended temperature strips are Thermax B 10-level strips having 10 values from 77°C to 127°C. Thermax strips are used to set the preheat temperature on the processor. These strips comprise steps of increasing temperature sensitivity. When the plate reaches a certain temperature, the step will change from white to grey/black. The highest step on the strip to become grey/black is the preheat temperature. Several strips should be applied to the back of a plate, at the leading edge, centre and trailing edge and aligned in the direction of processing. The plate should be fresh, do not use a plate which has been processed, the coating can aect plate temperature. After applying strips to the back of the plate, process the plate as normal. Read the temperature from the strips. Adjust the preheat setting on the processor if necessary and re-check the plate temperature with a new plate.

Check the Developer pH Use a good quality pH meter and calibrated electrode to measure the pH of the developer in the processor tank. ETAG recommends the HANNA HI 991000 pH /Temperature meter, and the WinLab Data Line pH-Meter with the WinLab Elektrode pH/T30. pH electrodes need careful storage and calibration to give an accurate reading. Calibrate the pH electrode with pH 7 and pH 10 buers. Do not keep the electrode in the developer solution for long periods as damage to the glass membrane can occur. Rinse the electrodes with water after use and store in water or pH 7 buer. Large errors are possible at the high pH values of Violet 500 developer. High pH solutions will damage the glass membrane on a pH electrode after prolonged immersion in the developer. To minimise errors, it is recommended that the pH of fresh developer is measured. Then measure the pH of the developer in the processor. Compare the two results. The advised operating range for pH is ±0.3 pH units vs. fresh developer. Change the replenishment rates if the pH goes outside the limits. Increase the anti-oxidation replenishment to increase the pH, and decrease the anti-oxidation replenishment to decrease the pH.

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 6

General Processor Settings for Violet Print plates

Parameter Transport speed Setting Set to give a dip-to-nip time in the developer of 19 to 21 seconds. Set to give Thermax strip reading on the back of the plate of 110°C - 116°C. 104°C - 116°C is allowed on processors where the preheat uniformity is not good, but this may give a little more variability in high screen ruling flat tints. Background fogging may occur at a Thermax strip temperature of 121°C or higher. Prewash Prewash options Prewash brush type Prewash brush speed Prewash brush nip pressure Prewash filter (if applicable) Developer Developer temperature Developer pH Developer pH limits in the processor Water at ambient temperature 1. Fresh water: this is the recommended configuration. 2. Recirculated water: choose a high setting for the water replenishment rate 1 Bristle brush Choose a high brush speed Medium pressure 50 micron cotton woven disposable filters are recommended if there is an option Fill the developer tank with Violet 500 developer 23°C ± 1°C A chiller unit will be required for the processor 12.2 ± 0.3 pH units versus fresh developer Whichever comes sooner: Developer life An upper limit on plate throughput of: · 1000 sq metres for a 20 litre developer tank volume · 2000 sq metres for a 40 litre developer tank volume · 3000 sq metres for a 60 litre developer tank volume Up to 8 weeks Developer top-up Replenisher Replenisher pH (Continued on next page) Not required Insert the replenisher pipe into a container of Violet 550R replenisher 13.0

Preheat

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 7

Parameter

Setting For plate throughput = 80 mls/m2 For "O" and "Standby" anti-oxidation = 40 ml/hr for 850 mm and smaller width processors = 80 ml/hr for greater than 850 mm processors

Replenishment rates

Note: a higher anti-oxidation rate may be required if the processor does not have an anti-oxidation cover protecting the developer. For 1250 mm and wider processors, the anti-oxidation rate may need to be set higher. Fine tuning of the replenishment rates may be required to maintain the developer pH within the specified range of ±0.3 pH units versus fresh developer, depending on the plate throughput profile.

Number and type of developer brushes Developer section brush speed Developer section brush nip pressure Developer filter section Rinse Rinse options Rinse brush type Rinse brush speed Rinse brush nip pressure Rinse filter (if applicable) Finisher life Plate drying temperature Prewash and rinse bath life

2 Bristle brushes (hard brushes, if there is an option) Choose a high brush rotation speed. Medium to hard pressure 50 micron cotton woven disposable filters are recommended Water at ambient temperature 1. Fresh water: this is the recommended configuration. 2. Recirculated water: choose a high setting for the water replenishment rate. 1 Bristle brush, if applicable Choose a high brush speed, if applicable. Medium pressure, if applicable 50 micron cotton woven disposable filters are recommended if there is an option Typically 1 to 4 weeks 50°C Fresh water ­ drain and clean weekly Recirculation ­ drain daily, clean weekly Rinse thoroughly with water, and avoid exposing the developer section to white light for prolonged periods. See Processor Care section. Comply with local regulations. Always use Kodak developer, replenisher and finishing gum. Compatibility is not guaranteed with competitors' chemistry.

Processor cleaning regime Waste disposal Compatibility with competitors' chemistry

Contact your local Kodak technical support if you need set-up information for a specific processor.

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 8

Processor Care

A regular maintenance and cleaning regime will produce a more consistent plate, minimising both downtime and remakes. During any maintenance of the processor and the handling of chemicals, suitable safety glasses and chemicalresistant gloves should be worn. Always refer to the Material Safety Data Sheets (MSDS).

Processor care checklist

Daily/shift change

1. Check that guards and interlocks are in position. 2. Check volumes in replenisher, finisher and overflow containers. 3. Check that developer temperatures are correct and the processor is in "Ready State" to accept a plate. 4. Check for developer and finisher circulation. 5. Check for correct water flow. 6. Check that plates are exiting the processor dry. 7. Check all spray bars are working correctly. If not, clear blockages and/or change filters. 8. On water recirculation processors, drain and refill prewash and rinse water tanks.

Weekly

1. Remove and clean prewash roller. 2. Check for leaks. 3. Lower the developer temperature set point by 2°C to check that the chiller is working properly. 4. Drain and clean the prewash and rinse water tanks. Check and clean the filters, if applicable. 5. Check the condition of the gum. Replace if necessary.

Every developer change

1. Isolate the processor and empty all the tanks. 2. Clean the developer section under safelight, or subdued white light. Strong white light could harden any coating deposits left in the developer section. It should be possible to clean the developer section without removing brushes or rollers. Remove the developer filters, and using a wash down hose, thoroughly clean developer tank, rollers and brushes. Avoid the use of acidic processor cleaners as residues could lower the developer pH considerably. Ensure that the wash water is completely drained from the tank. 3. Thoroughly clean the prewash and rinse sections with a wash down hose. Cleaning should be possible without removing the brushes. 4. Clean the gum section with a wash down hose. 5. If the processor is very dirty, remove all the rollers and brushes and clean the tanks thoroughly with water. Wash the brushes and rollers with water. If the rollers are heavily contaminated it is possible to clean them with a UV wash (e.g. Varn UV Wash). Rinse the rollers thoroughly with water after using any chemical washes. 6. If the brushes and rollers have been removed, make sure that the brush pressures are correctly reset when re-installing the brushes and make sure that all rollers are replaced in their original positions. 7. Install a new set of filters. 8. Refill the developer section with fresh Violet 500 developer. 9. Change gum barrel with fresh, working-strength 850S finisher. 10. Refill prewash and rinse tanks, if appropriate. Add Kodak 150 additive K, as directed on the container, to the prewash and rinse section if bacterial fouling is a problem.

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 9

Baking Parameters

Exposure for baking Baked plate finisher Baking solutions Baked plate cleaner Conveyor oven Static oven Colour of baked plate

1

Normal exposure Kodak 850S plate finisher Kodak Ultratherm baking solution Kodak 804 baking solution (EAMER) Kodak 550 plate cleaner 220°C at 1.0 m/minute1 200°C for 8 minutes1 Unchanged from non-baked plate

Parameters are for guidance only.

Platesetter Exposure and Linearisation Set-Up

General

The operating exposure for the plate is defined as the exposure needed to give good image resolution and run length. Violet Print plates are negative working. The recommended operating exposure, as expressed by the Stouer or UGRA step wedge reading, is chosen to give good run length without excessive dot gain or loss of line resolution. Violet Print plates will show better line resolution and require less linearisation if the exposure is below the operating exposure, but the run length capability of the plate will fall. The dot gain for Violet Print plates is non-linear at the operating exposure, with the degree of non-linearity becoming greater as the screen frequency increases. Non-linearity also depends on the exposure; it is higher at over-exposures and lower at under-exposures. For optimum tonal resolution at the operating exposure, linearisation is required. The type of platesetter will influence the resolution delivered by the plates. For internal drum platesetters up to 2% - 98% at 200 lpi can be achieved, although generally 175 lpi is recommended. For flatbed platesetters up to 2% - 98% at 175 lpi can be achieved, although generally 150 lpi is recommended. With the processor set up and ready to go, the platesetter can now be set up for exposure and linearisation.

Equipment

Step Wedge In this document, we refer to UGRA and Stouer step wedges. Specifically, by UGRA we mean the `UGRA Plate Control Wedge 1982', and by Stouer we mean the `Stouer 21 Step' step wedge. These step wedges are in intervals of 0.15 density units. For the UGRA step wedge, step 1 = 0.15 neutral density units, and for the Stouer step wedge, step 2 = 0.15 neutral density units. UGRA step 1 = Stouer step 2, UGRA step 2 = Stouer step 3, etc. Plate Reading Device For linearisation of the tonal range you will need to use a standard densitometer or plate reader. For densitometers, such as the Gretag D19C, the Yule-Nielsen value is 1.07. Plate readers such as the Gretag IC Plate II can also be used and these do not require a Yule-Nielsen factor to be applied.

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 10

Using Step Wedges to Set Platesetter Exposure The step wedge is taped onto the coating (emulsion) surface. This is done by attaching small pieces of tape to the top and bottom of the step wedge, ensuring that the step wedge is firmly fastened to the plate. Avoid covering the scales on the step wedge when taping the top and bottom. Be sure to place the step wedge parallel to the gripper edge. The plate area covered by the step wedge is given a solid exposure on the platesetter. After exposure, remove the step wedge and process the plate as normal. The image of the step wedge on the plate may show weak `tail' steps, depending on the processing conditions. The `tail' steps can be removed by gently rubbing the step wedge image with a cloth or wipe dampened with water. They become more dicult to remove as the processed plate ages. Do not use developer to rub away the step wedge image. Evaluate the step wedge readings either visually, or with a densitometer or spectrodensitometer. Visual assessment of the step wedge image can give rise to problems of interpretation. An alternative method is to measure the density of each step with a densitometer or spectrodensitometer. If you are using a Gretag D19C densitometer, use the Plate Measurement function and take the solid readings at each step on the step wedge. For other plate readers, make the readings with the device set on cyan. Adjust the platesetter exposure power to give the required step wedge readings. Note, this may have to be by trial and error since the exposure units on the platesetter are not always linear. However, as a guide, to increase the step wedge reading by 1 step, increase the exposure by 1.4 times (e.g. 100 increased to 100x1.4 = 140); to decrease the step wedge by 1 step, decrease the exposure by 0.7 times (e.g. 100 reduced to 100x0.7 = 70). Aim to get step wedge readings as illustrated in the pictures and charts below. These step wedge readings are for guidance only. Lower step solids may give shorter press run lengths but better line resolution and less dot gain. Higher step wedge readings may not give improved press performance. Note: Step wedges become damaged and worn or discoloured with use. Replace with a new step wedge occasionally. Step wedges that have accidentally gone through the processor cannot be used again and must be discarded.

UGRA and Stouer step wedge image, after cleaning with water-damp cloth

Exposure for Violet Print plates

UGRA solid 2, clear 4/5 after cleaning a fresh plate with a water-damp cloth. Stouer solid 3, clear 5/6 after cleaning a fresh plate with a water-damp cloth.

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 11

Using Dot Gain Measurements to Set Exposure

It may be the case that a step wedge cannot be used, for example if the platesetter and processor are in-line and it is impossible to recover the step wedge from the plate before it enters the processor. Mid-tone dot gains can be used in these situations. However, platesetters will have varying degrees of dot gain depending on the architecture of the platesetter (internal drum or flat bed), the design of the optics and the screen ruling and dot shape being used. Check with your local Kodak technical representative if you need information for a specific platesetter.

Linearising the Platesetter

Expose a plate to a digital tonal range at the operating exposure determined using a step wedge or other method. Measure the tonal values with a reliable densitometer or plate reader. Input the measured values to the calibration manager available in the platesetter RIP. Make another plate. The tonal range on the plate should now be linear, typically to within ±1% of the nominal dot percentage. Press calibration can be applied to the linearised tonal settings if required.

Note: it may be necessary to linearise each plate gauge. Although the plate speed as measured with a step wedge may be the same, dierences in the platesetter and in the plate processing can introduce dierences in the dot gain curves.

Press

As with all CTP plate products, Violet Print plates require compatible fount solutions and press chemicals to obtain optimum press performance. Please contact your local Kodak technical representative to advise on compatible pressroom products.

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 12

Troubleshooting -- Plate / Platesetter / Processor problems

Dot loss on the plate Room conditions Plate left too long between exposing and processing latent image stability Must be used in a controlled environment of 21°C - 24°C and 40% - 60% relative humidity. High humidity will lead to dot loss and weak solid images. Process within 10 minutes after exposure. Check the age and the pH of the developer. Check the preheat and developer brush pressures. Processor related Read the label on chemistry containers before adding chemistry to the processor. It is important that developer and replenisher are used as instructed. You cannot substitute one for the other. Ensure that the packs of plates are stored correctly. Check plate speed with a step wedge. Increase the platesetter power and re-linearise. Reset exposure, contact platesetter manufacturer.

Storage conditions of the plates Change in plate speed Drift in laser power

Dot gain on the plate Room conditions Must be used in a controlled environment of 21°C - 24°C and 40% - 60% relative humidity. High temperature will lead to an increase in plate speed and therefore dot gain. Check safelight integrity; ensure the plate is not left more than 15 minutes under the recommended safelight. Violet Print plates have no tolerance to white light. Check the age and the pH of the developer. Check the preheat and developer brush pressures. Processor related Read the label on chemistry containers before adding chemistry to the processor. It is important that developer and replenisher are used as instructed. You cannot substitute one for the other. Ensure that the packs of plates are stored correctly. Check plate speed with a step wedge. Decrease the platesetter power and re-linearise. Reset exposure, contact platesetter manufacturer.

Plate fogged before or after exposure

Storage conditions of the plates Change in plate speed Drift in laser power

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 13

Unevenness in tints around the plate Developer brush pressure Platesetter related Uneven plate coating / sensitivity (e.g. edge fogging, broken external wrapping) Uneven coating weight of either the photo-layer or top-layer Out-of-focus condition on platesetter - plate not suciently in contact with the platesetter drum or on the platesetter flatbed Check the pressure is set correct and that it is even from side to side. For example, dirty optics, incorrectly aligned optical path, out-of-focus. Contact the platesetter manufacturer for technical support. Try new batch or pack of plates.

Try a new plate batch.

Check contact between plate and platesetter bed. Check that the platesetter bed is clean. Look for plate edge burr, coil set.

Periodic banding seen in the background, especially in the halftones Developer brush pressure. On some processors getting the correct brush pressure can be dicult, especially for multiple gauge users and at high screen rulings. This leads to processor banding parallel to the developer brushes. Exhausted developer

Optimise the developer brush pressures. Change the developer more frequently than recommended in the set-up procedure.

See above. Check that the developer usage rate is within recommended limits. It might be the case that light leakage or flare during exposure is making the background more dicult to develop. Check that the exposure is correct for the application. For example, dirty optics, incorrectly aligned optical path, out-of-focus. Contact the platesetter manufacturer for technical support.

Over-exposure

Platesetter related

Loss of detail in text or linework, relief text filling in Plate has been given too much exposure Development brush pressure Platesetter related Re-check that the operating exposure is correct. See comments in the box above. For example, dirty optics, incorrectly aligned optical path, out-of-focus. Contact the platesetter manufacturer for technical support.

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 14

Weak image on the plate Room conditions Storage conditions of the plates Change in plate speed Humidity too high, leading to slow plate speed and weak image. Ensure that the packs of plates are stored correctly. Check plate speed with a step wedge. Increase exposure if necessary. Check the pH of the developer in the processor. Read the label on chemistry containers before adding chemistry to the processor. It is important that developer and replenisher are used as instructed. You cannot substitute one for the other. Check that the replenishment rates are set correctly. If necessary, fine tune (reduce) the anti-oxidation rate to maintain pH during the life of the developer. Developer temperature too high Processor throughput speed too slow Lack of developer circulation Preheat temperature too low Platesetter related Check processor settings are correct and the developer chiller is working. Use a hand-held thermometer to check the developer temperature. Check that the processor settings are correct. Measure dip-to-nip time in the developer. May be due to blocked filters or closed taps. Check the preheat temperature by using a Thermax strip on the plate back. For example, dirty optics, loss of laser power, out-of-focus. Contact the platesetter manufacturer for technical support.

pH of the developer in the processor is too high

Background stain on the plate Preheat temperature too high Plate fogged Check the preheat temperature by using a Thermax strip on the plate back. Ensure that the plate has not been exposed to white light, or left out in safelight for too long. Check the pH of the developer in the processor. Ensure that replenisher and not developer is being used to replenish. Check that the replenishment rates are set correctly. If necessary, fine tune (increase) the anti-oxidation rate to maintain pH during the life of the developer. Check processor settings and that the developer heater is working. Use a hand-held thermometer to check the developer temperature. Change developer. Check that the processor settings are correct. Measure dip-to-nip time in the developer. Check and adjust brush pressure. Renew if necessary.

pH of the developer in the processor is too low

Developer temperature too low Developer exhausted Processor speed too fast Brushes in the developer section - pressure set too low. Worn-out or damaged brushes

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 15

Thinner gauge plates are not fully developing, but thicker gauge plates are correct Developer brush pressure not set correctly The developer brush pressure should be set to the thinnest gauge plate to give a slight resistance as a piece of plate is passed between the brush and the developer bed.

De-interleaving problems -- paper dicult to remove Room humidity is low Interleaving is stuck to the plate surface Platesetter related Maintain the specified relative humidity of 40% to 60%. Damage during transportation, storage or use. Mechanical problems. Contact the platesetter manufacturer for technical support.

Plate transport, or punching problems Plates are bent or kinked due to mishandling Plates have excessive coil-set Equipment fault Use correct storage, handling and loading procedures. Contact the local Kodak technical support. Contact the Platesetter / Equipment Engineer.

Scratch or scu marks in the image Brushes in the developer section - pressure too high Debris in the processor Check and adjust brush pressure. Clean the processor.

Unacceptable variability in the image quality Reduce the screen ruling being used. Screen ruling being used is outside the system capability For internal drum platesetters the recommended screen ruling is 175 lpi (upper limit 200 lpi). For flatbed platesetters the recommended screen ruling is 150 lpi (upper limit 175 lpi). Condition of the plate batches Room conditions Check batch age. Check storage conditions. Check variability in room temperature and humidity over the shift period. For example, dirty optics, variable laser power, incorrectly aligned optical path. Contact the platesetter manufacturer for technical support.

Platesetter related

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 16

Troubleshooting -- Press

Scumming at start up or early into the press run Scum is visible on the plate and cannot be removed with water. (Coating still present in non-image areas of plate). To test for background scum, use a negative deletion pen on the area. If the plates no longer take ink, it is a scumming condition. If the deleted area continues to take ink, then it is a tinting problem. Over-exposed plate Plate was processed at excessive speed or a too low developer temperature Plate developer exhausted or contaminated Ensure that the platesetter is set at the correct operating exposure setting. Set processor to correct settings. Change to fresh developer when the maximum plate throughput or developer life has been reached. Ensure rinse water does not feedback into the developer section of the processor. Check the condition of the developer, prewash and rinse section brushes. Adjust or replace if necessary. Change to fresh finisher when the maximum plate throughput has been reached. Check the condition of the finisher application rollers. Adjust or replace if necessary. Wash the dampening roller sleeves regularly. With older conventional dampening systems, the roller sleeves require replacing more often than with newer systems. Clean rollers with solvent cleaner and desensitise chrome rollers. Check fountain solution dosage. Too much ink being run Re-adjust ink/water balance for minimum ink and fountain solution feed. Ensure sucient alcohol or alcohol replacement is being used for the type of dampening system used. Do not mix one step fountain solutions to less than the manufacturer's minimum recommended concentrations. Reset the rollers to the correct roller stripe width. Correct the plate and/or blanket packing to the minimum needed for good ink transfer.

Insucient processor brush action Plate finisher is exhausted Insucient desensitisation by plate finisher

Dampening system contaminated with ink and/or wash up chemicals

Insucient dampening

Excessive roller and/or plate to blanket pressures

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 17

Scumming after a clean start up and several thousand impressions into a run Scum is visible on the plate and cannot be wiped o with water. (Coating still present in non-image areas of plate). To test for background scum, use a negative deletion pen on the area. If the plates no longer take ink, it is a scumming condition. If the deleted area continues to take ink, then it is a tinting problem. Fountain solution is too weak Fountain solution is too warm Insucient amount of alcohol in fountain solution, if alcohol is used The non-image area of the plate is worn excessively Fountain solution contaminated from ink and / or paper feedback, resulting in too high a pH with unbuered fountain solution Increase the fountain solution concentration, but do not exceed the manufacturer's recommended amount. Check fountain solution chillers are maintaining a correct and constant temperature of the fountain solution during the press run. Replenish alcohol to maintain a constant level during a press run. Ensure automatic alcohol level controllers are functioning correctly. To prevent excessive non-image wear, wash blankets more often during the print run. Check plates, blanket and forme roller pressures. Drain fountain solution and replace with a fresh batch. To reduce excessive contamination, change fountain solution more frequently or use a solution with better buering.

Tinting Emulsified ink suspended in the fountain solution appears on the printed sheet, but is easily wiped o the plate with water. To test for tinting, use a negative deletion pen on the area. If the plate continues to take ink, then it is a tinting problem. If the deleted area no longer takes ink, it is a scumming condition. Ink pigments bleed into the fountain solution Excessive roller and printing pressures Fountain solution is too acidic, breaking down the ink Reduce the amount of alcohol or change to an alcohol replacement, which is compatible with Violet Print plates. Check and adjust roller pressures and plate to blanket pressures to the minimum needed for good ink transfer. Adjust the pH to a higher value. Consult with the fountain solution manufacturer for a solution more compatible with the water used. The plate substrate can be damaged if the pH of the developer in the processor is too high. Check if the pH of the developer in the processor is within ± 0.3 pH units of fresh developer. If necessary, change the developer in the processor. Check that the replenishment rates are set correctly. If necessary, fine tune (reduce) the antioxidation rate to maintain pH during the life of the developer.

Substrate attack

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 18

Ink and water balance Frequent water feed adjustments have to be made to maintain print quality. Excessive amount of fountain solution is being run Dampening rollers improperly set Ink rollers improperly set Reduce water feed. If that results in sensitivity well into the press run, the fountain solution may be too weak. Increase the concentration of fountain solution. Reset the rollers. Reset the inking rollers to the press manufacturer's specifications.

Image blinding at start up Image will not accept ink or is slow to roll up. Too much finisher on plate Wash the plate with water. Check finisher section of processor for correct roller and settings and appropriate flow. Thoroughly rinse the plate and never allow plate cleaners to dry on the image areas. Sometimes wiping over the plate with the same cleaner used initially and following immediately with a water rinse can revive a plate. Image can be lost at the start of a re-run if an unsuitable plate cleaner has been used to wash the plate at the end of the previous run. Clean and deglaze or replace rollers and blanket. Consult the ink manufacturer. Reduce fountain solution feed. If problem persists, consult the ink manufacturer. Drain and replace the fountain solution with a fresh batch. If the problem persists, try a dierent paper or consult the paper manufacturer. See comments in "Troubleshooting - Plate /Platesetter /Processing Problems" on page 15 under weak image.

Plate cleaners have dried on the plate

Glazed rollers or blanket Ink is too short and / or too high in tack Ink is too water-resistant or taking up too much fountain solution Fountain solution contaminated with paper sizing Weak image

Image blinding after several thousand impressions. Image sharpens, or loss of image in isolated areas. Ink, fountain solution, paper, plate incompatibility Alcohol free concentrates and / or alcohol replacements are mixed incorrectly Chemicals from inks and paper can react with the fountain solution and the plate surface to form insoluble, water receptive compounds on plate image and non-image areas. Consult consumable manufacturers. After excess amounts of alcohol replacements are used, the ink will lose tack and will also loose its ability to be transferred in the ink train. Consult with the fountain solution manufacturer.

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 19

Plate image wear Use a less abrasive ink. Some white inks, or opaque inks mixed with white, can be very abrasive. Kodak Violet Print plates should be baked when printing with UV inks. Plates can also be baked for additional run length for abrasive press conditions. Change to a paper with better pick resistance, change to an ink with less tack, reduce press speed or wash blanket more frequently during the run. Reduce packing to a minimum pressure needed for sucient ink transfer. Refer to press manufacturer specifications. Reset rollers to manufacturers specifications. Increase bearer pressure so that the cylinders are not riding on the gears. Refer to press manufacturer specifications. Use chemicals which are compatible with the blanket or rollers. Consult blanket and roller manufacturers for recommendations. Test the chemicals by placing on a solid area of a processed plate for approximately 5 minutes. Wash o with water and check for damage to the coating. Test cleaners as above. Check pH of the fountain solution. If the pH is 3.5 or lower and mixed to the minimum manufacturer's recommended concentration, it may not be suitable with the water used. Consult with the fountain solution manufacturer for alternatives. The thinner ink film causes plate wear in the ghost areas before the rest of the image area. Run more ink if possible or use ink with less pigment loading. An oscillating ink roller may reduce ghosting, but if pigment content of the ink is too high, the entire plate may wear early. Check press chemicals, fount concentration and temperature. Check alcohol percentage. Alcohol at concentrations above 10% can induce image break-down during the press run. Check ink quality and oleophilic feeding properties, try other inks. Recheck that the operating exposure is correct, and that the platesetter is working correctly with even exposure across the plate. Short run length (unbaked plates) Check Thermax strip, adjust preheat setting if necessary. Check that all processing parameters are in specification. Check humidity in prepress room; relative humidity should be no higher than 60%. Check if plates were processed within 10 minutes after exposure. (Continued on next page)

Abrasive ink and /or paper

Paper fibres, coating or fillers piling on image areas of blanket Plate and / or blanket packed too high Rollers set too tightly to the plate. (Wear is more pronounced on

the lead edge of the plate)

Insucient bearer pressure

(Wear is evenly spaced streaks parallel with the plate cylinder)

Press chemicals cause blanket or rollers to swell Press chemicals are not compatible with the plate coating Plate cleaners are not compatible with the plate coating Fountain solution is too acidic or alkaline Ink starvation (Image wear takes place in an area where there is an ink ghost) Sharpening of image, particularly highlight dots during the press run

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 20

Check press parameters are optimised. Check that the plate is fully baked with the deletion gel test. Place a deletion cross on a solid area of baked plate for 5 minutes. Wash o with water and check for any attack to the coating. If no attack, the plate is fully baked. Check that the baking parameters are correct and the oven is maintaining the correct temperature across the whole plate. Non-image wear Reduce water feed if possible. Change to a blanket with less tack Paper fibres, fillers or coating pile in non-image areas of the blanket Ink takes up fountain solution too fast. (Metal polish following an image area) An abrasive ink (usually the black) prints back onto the blanket of the next printing unit, polishing non-image area. Polished areas show the images of prior plate Polishing of non-image area Change to a more moisture resistant paper. Wash blanket more frequently. Consult paper manufacturer. Try a dierent type of fountain solution. If the problem persists, consult the ink manufacturer.

Short run length (baked plates)

Use a more absorbent paper, a faster setting ink, a shorter ink or reduce ink feed to the prior unit if possible. Wash blanket more frequently.

Check plates, blankets and forme roller settings.

Plate cracking Plate not tight on the press cylinder Plate packing short or not aligned correctly Plate bender not square Incorrect plate thickness Cylinder gap dirty Cylinder edge has burr or build-up of dried ink Lead and / or tail edge of plate improperly bent Excessive ink and / or dampening roller pressure causes lead edge of plate to flex.

Kodak Violet Print digital plates CIM/ETAG May 2006

Check for fit after mounting the plate. Check the packing for proper length. Make sure the packing cannot move during the run. Carefully align the packing sheets during initial mounting. Check bender alignment. Measure the plate for squareness. Check thickness of plate for correct mil spec. Clean the cylinder gap. Clean and de-burr the cylinder edge.

Check plate bends for proper fit in the cylinder gaps.

Reset rollers for minimum recommended plate contact.

Page 21

Plate scratching Improper plate handling Roller contamination with hard particles. (Continuous scratches around the entire plate in the direction of the cylinder rotation) Handle plates with care. Most CTP plates are more sensitive to improper handling than conventional plates. Locate and eliminate the source of the contamination, remove the particles if possible or scrub the rollers. Replace the rollers if the problem persists.

Gouges in plate Blanket is contaminated with hard particles Locate and eliminate the source of the contamination, replace the blanket and clean the inking system.

Kodak Violet Print digital plates CIM/ETAG May 2006

Page 22

Subject to technical change without notice.

Eastman Kodak Company 343 State Street Rochester, NY 14650 USA

©Kodak, 2006. Kodak and Violet Print are trademarks of Kodak. All other trademarks and registered trademarks used herein are the property of their respective owners.

W.PC.O28.0506.en.01

Information

CIM_VioletPrint_A4_May2006_v5.indd

25 pages

Report File (DMCA)

Our content is added by our users. We aim to remove reported files within 1 working day. Please use this link to notify us:

Report this file as copyright or inappropriate

552859


You might also be interested in

BETA
24-CTP Plates.indd
CIM_VioletPrint_A4_May2006_v5.indd
RptFlyer