INTRODUCTION TO SILVER DIGIPLATE

Computer-to-Plate
INTRODUCTION TO SILVER DIGIPLATE
This manual describes the characteristics of the
Mitsubishi Silver Digiplate and provides potential
users with recommendations for integrating this
method into their existing plant.
Mitsubishi International GmbH
Graphic Art Materials Division
Kennedydamm 19
D-40476 Düsseldorf, Germany
Tel.: + 49-211-4397-369
Fax: + 49-211-4397-461
http://www.mig.de
Mitsubishi Paper GmbH
Am Albertussee 1
D-40549 Düsseldorf, Germany
Tel.: + 49-211-53596-206
Fax: + 49-211-53596-222
http://www.mitsubishi-paper.de
INTRODUCTION TO
SILVER DIGIPLATE TECHNOLOGY
Computer-to-Plate
Application of Silver
Digiplate polyester and paper printing
plates
CONTENTS
CONTENTS
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Product information Silver Digiplate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.0
1.1
1.1.1
1.1.2
1.2
1.2.1
1.2.2
1.2.3
1.3
1.4
1.4.1
1.4.2
Output methods for Silver Digiplate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Imagesetter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Output mode
Resolution
Calculating the Optimum exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Laser intensity
Calibration
Ongoing checking
Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Punching, cutting, bending . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Re-punching
Bending polyester plates
2.0
2.1
2.2
2.2.1
2.2.2
2.2.3
2.3
2.3.1
2.3.2
2.3.3
Proofing-solutions and Color management for Silver Digiplate . . . . . . . 13
Application of the proofs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Workflow profiling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Printing machine profiling
Proof printer profiling
Profiling principles
Usage of the ICC-Profiles on Mitsubishi SDP-RIP . . . . . . . . . . . . . . . . . . . . 14
Different color gamuts through Rendering Intents
v-Dot-Plugin - integrated RIP- Proofsolution
Inkjet-Proof materials from Mitsubishi HiTec Paper
3. 0
3.1
3.1.1
3.1.2
3.1.3
3.1.4
3.1.5
Printing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Print settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Dampening solution
Alcohol or alcohol substitutes
Setting the press
Adjusting the dampening solution
Additional dosing units
4.0
4.1
4.1.1
4.1.2
4.1.3
Dampening solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Troubleshooting (scumming) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Removing ink from the plate
Checking the press settings
Using dampening solution additives
5.0
Inks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.0
6.1
6.2
Cleaning solution and print dusting powder . . . . . . . . . . . . . . . . . . . . . . 20
Cleaning solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Print dusting powder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
7.0
7.1
7.2
7.3
Starting up the press . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Combined dampening systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Separate dampening systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Restarting the press . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
8.0
Recommendations for non-standard presses
. . . . . . . . . . . . . . . . . . . . . 22
3
CONTENTS
9.0
9.1
9.2
9.3
9.4
10.0
10.1
10.2
10.3
10.4
11.0
11.1
11.2
12.0
12.1
12.2
12.3
12.4
12.5
13.0
13.1
4
Plate clamping procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Backing sheet under the plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Plate clamping bars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Clamping the SDP plates on presses with
no autoplate system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Clamping the SDP plates on presses with
an autoplate system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Multi-colour printing with SDP plates,
taking the Heidelberg PM 46 /QM 46 as an example . . . . . . . . . . . . . . . .24
Basic machine settings and prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Clamping the plates with an autoplate system . . . . . . . . . . . . . . . . . . . . . 25
Start-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Register with polyester plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Four-colour printing with SDP plates,
taking the RYOBI 3304H as an example . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Basic machine settings and prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . 26
Optimising the register printing for Ryobi 3304 . . . . . . . . . . . . . . . . . . . . 26
Four-colour printing with SDP plates,
taking the Heidelberg SM 52 as an example . . . . . . . . . . . . . . . . . . . . . . . 27
Basic machine settings and prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Clamping the plates with an autoplate system . . . . . . . . . . . . . . . . . . . . . 27
Start-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Register with polyester plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Optimize register printing for SM 52 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Four-colour printing with SDP plates,
taking the RYOBI 524H as an example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Basic machine settings and prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . . 29
14.0
Polyester printing plates
on 4-up and 8-up sheet-fed presses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
15.0
Polyester printing plates on web offset presses . . . . . . . . . . . . . . . . . . . . 30
16.0
Polyester printing plates on envelope printing machines . . . . . . . . . . . . 30
17.0
17.1
17.2
17.3
17.4
17.5
17.6
17.7
17.8
17. 9
17.10
17.11
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Exposure problems (producing plates) . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Faulty reproduction (causes associated with the processor) . . . . . . . . . . . 31
Faulty reproduction (other causes) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Scumming problems (Prerequisite: well exposed printing plate) . . . . . . . 32
Faulty reproduction (other causes) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Voids in printing area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Poor ink acceptance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Poor reproduction of screen ruling points . . . . . . . . . . . . . . . . . . . . . . . . . 34
Emulsification of ink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Roller-stripping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Register alignment differences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
INTRODUCTION
INTRODUCTION
Silver Digiplate (SDP) is an extremely advanced offset-plate technology based on the same principles as silver-halide photography;
SDP plates are exposed directly in a polyester plate imagesetter or
other film imagesetter, without any intermediate processes,
Silver Digiplate is available in the form of polyester or paperbased plates.
Silver Digiplate is distinguished by its excellent workability despite the minimal process maintenance requirement. SDP is compatible with the majority of laser imagesetters and is ideal for use
with conventional offset presses.
This manual describes the characteristics of the Mitsubishi Silver
Digiplate and provides potential users with recommendations
for integrating this method into their existing plant.
This manual may not be duplicated or reproduced without the
prior permission of Mitsubishi Paper Mills Ltd.
5
PRODUCT INFORMATION
Product information: Silver Digiplate
Designation
Material
SDP-FRm175
Material
thickness
Light source
Max. Print run
Film, matt 0.20 mm
reverse
side
Red-LD (633-680 nm)
He-Ne (633 nm)
20,000 sheets
SDP-FR100/175
Film
0.12/0.20 mm
Red-LD(633-680 nm)
He-Ne (633 nm)
20,000 sheets
SDP-RR 175
Paper
0.14/0.19 mm
Red-LD(633-680 nm)
He-Ne (633 nm)
10,000 sheets
SDP-FE175
Film
0.20 mm
LED (670-680 nm)
20,000 sheets
SDP-FD100/175
Film
0.12/0.20 mm
Infrared (780 nm)
20,000 sheets
SDP-RD175
Paper
0.14/0.19 mm
Infrared (780 nm)
10,000 sheets
Maximum screen ruling: 70 lines/cm (175 l/inch), 3-97%
The material is available in rolls or sheets up to 1,090 mm wide for all standard imagesetter
specifications.
Designation
Purpose
Packaging unit
SLM-AC Activator
Processing chemical
10l canister
Notes
Formulation:
AC+water = 1 + 1
SLM-ST Stabilizer
Processing chemical
10l canister
SLM-EAC Eco-Activator
Processing chemical
10l canister
Formulation:
ST+water = 1 + 3
Ready for use,
for Eco-Prozessor
SLM-EST Eco-Stabilizer
Processing chemical
10l canister
SLM-OE III Pen
Correction pen
3-Pack
SLM-OE
Correction fluid
100 ml bottle
SLM-OH
Etching and plate-
5l canister
Ready for use,
for Eco-Prozessor
Narrow tip
cleaning solution
SLM-OD30
Dampening solution
5l canister
additive
Conventional and
continuous-feed
dampening systems
SLM-OD50
Dampening solution
5l canister
additive
SLM-OA1
Dampening solution
dampening systems
1l bottle
additive
SLM-OA2
6
Dampening solution
additive
Alcohol reduced
1l bottle
Brief-Guide-2005_GB_2c.qxd 11.01.2005 13:52 Seite 9
OUTPUT METHODS
1.0
OUTPUT METHODS FOR SILVER DIGIPLATE
1.1
Imagesetter
1.1.1
Output mode:
Images are output on Silver Digiplate in
negative/right reading mode, i.e. the printing
areas are unexposed (silver) and the nonprinting areas are exposed (black).
1.1.2
Resolution:
The resolution of the imagesetter is
depending on its specifications and the
requested result.
The maximum recommended screen ruling for
Silver Digiplate is 70 lines/cm (175 Ipi). It is important
to set a sufficient imagesetter resolution for the selected screen
ruling, in order to be able to reproduce the required 256 grey
levels.
Special ruling processes such as "Extra Gray Values" from Harlequin
can produce smooth runs and sufficient grey levels even with nonoptimal combinations of screen ruling and resolution.
1.2
Calculating the optimum exposure
This important task is divided into three steps: setting the laser intensity, calibrating the screen ruling and continually checking the results.
1.2.1
Laser intensity:
The laser intensity setting (density) has a considerable influence on
the quality of the printing results, particularly with four-colour
printing. For an imagesetter test, the processing chemicals should
ideally only be a few days old. The aim when calculating the optimum density setting is to find the point immediately preceding
the maximum blackening of the emulsion layer. It's difficult to
provide absolute guidelines for density values because the Silver
Digiplate material works very abruptly and the range between
over- and underexposure is very small.
7
OUTPUT METHODS
We recommend the following
process:
Carry out a test exposure of fine
positive and negative lines, e,g, the
Mitsubishi SDP Control Chart (Fig. 1),
This test job contains several
elements designed to help you to
check the optimum exposure, e,g.
fine vertical and horizontal line
structures, fine positive and negative
text, halftone patches, etc. The test
should be carried out several times in
succession with various different
laser settings. The selected gradations should not be too fine, so that a
good setting may be roughly calculated more quickly.
Fig. 1
The exposed plates might display the following results, which
should be evaluated with a powerful magnifier (e.g. 20x):
Correct exposure
Overexposure
In principle, positive and negative lines should be equally well defined. For subsequent printing it is important to know that slight overexposure (more blackening on the plate) helps to prevent background scumming and filling in. Slight underexposure (silver image on
the plate), on the other hand, helps to stabilize fine lines and prevent
the image either from being too pinsharp or from disappearing.
8
OUTPUT METHODS
Alternatively, uncalibrated ruling points with 3% up to 97% can be
output. Thereby it must be insured that no calibration is activated,
otherwise the result can be falsified. In case of the optimum exposure
the 3% and 97% point on the plate should be reproduced very well.
The exposure values must be calculated individually for each exposure resolution. Often, lower resolutions require higher laser settings.
1.2.2
Calibration:
The RIPs' calibration programmes offer various different ways of
influencing the output. For this reason, it is important to first establish what the calibration is intended to achieve. In general, a calibration is intended to achieve repeatable results.
Thereto two stages can be distinguished:
1. Measurement of the screen ruling points directly on the printing
plate to obtain a linearization of the printing plate; this can be
performed with a normal densitometer. Precise values will be
measured with scanner based gauges.
Caution: Densitometers with polarizing filters are not suitable for
the measurement on Silver Digitplate!
The printing result will appear more saturated.
2. Measurement of the printing result to include the influence of
the machine and the paper etc. in the measurement. This method
needs a little effort but enables a precise variation of the printing
result. After introduction of CtP in printing houses, jobs are processed as well using the conventional techniques as a rule.
Therefore we recommend producing a printing plate with a suitable test-chart with gradated halftone patches (e.g. Mitsubishi test
chart), once conventionally with film and once by CtP. Both will be
printed under the same conditions and compared one another.
Afterwards the CtP result can be adapted by calibration to the
conventional production printing result.
9
OUTPUT METHODS
This will ensure that the printing results from the different
production methods can be mixed together. As alternatives to this
so-called in-house standard, calibration can also be performed to
other values, e.g. FOGRA.
The individual steps of calibration:
• First set the optimal density.
• Print out the testchart without calibration (linear).
• Proof-print under Standard printing conditions.
• Measure the printing result.
• Alter the ruling percentages in RIP so as to achieve
the desired result.
This calibration may be
performed either for one colour
only, e.g. cyan, or for all four process colours. The uncalibrated Silver Digiplate generally requires
heavier correction in the lightest
areas (up to 15%) and the shaded
areas (90% or more). In the midtone area, on the other hand, it is
common for little or no alteration
to be required.
10
OUTPUT METHODS
1.2.3 Ongoing checking:
To enable a simple check to be made during production of the
optimal thickness value, Mitsubishi Paper offers digital LTCheck.eps test strips (fig. 3), which can be exposed at the gripper
margin of each plate. Fine lines and screen percentage facilitate
an excellent exposure judgement. This contains furthermore a
specially arranged series of digits which enables any change in
the density to be read off simply.
Caution: The numerical sequence can not be used to determine a
correct exposure, due to the fact that calibration, screen resolution and angle influences the exposure.
Fig. 3
LT-Check.eps
The exposure results may vary as a result of:
• variations in or ageing of the light source.
• dirt in the optical Systems.
• the processing conditions.
• insufficient processing chemicals.
• different emulsion batches of the plate material.
1.3
Processing
High-quality printwork and uniform results are only possible if the
processing conditions are absolutely consistent. Scratch-free, uniform processing is essential. You can check whether or not your
film processor processes uniformly with the aid of an unexposed
silver plate.
Activator
Stabilizer
Processing time
17-25 sec.
Temperature
28-31°C
Room temperature
PH-value
> 12.8
<7.0
Replenishment
150 cc/m2
200 cc/m2
Chemicals require changing in case of poor pH-value or after 4 weeks
Set drying temperature at 40-50 C.
If there is a water-tray present, fill it with water.
A mains water connection is not required.
11
OUTPUT METHODS
1.4
Punching, cutting, bending
1.4.1
Punching
A number of different imagesetters are cutting and punching the
polyester plates fit for the printing machine.
Many imagesetters possess a very accurate material guide, in order
that the printing plates can be output without internal punching.
The specific punching profile will be manufactured in an aluminium plate punch. Imagesetters with integrated triple-hole film punches (e.g. Bacher 2000) require a re-punching device for the execution of the printing-plate punching. The re-punching can be
performed with a conventional hole-punch or with a special register-punch (e.g. from Beil Registersysteme GmbH). On different
imagesetters it's possible to install, as an optional, a registersystem with U-profiles for the printing machine. In these cases it's
not necessary to reprocess and re-punch the plates.
1.4.2
Bending polyester plates:
Several modern types of presses, equipped with an automatic plate-loading system, require the plates to be bended. Polyester plates that are used in autoplate presses must be bended by thermal
means. The Beil and Bacher bending units are recommended for
the 4- or 8-page format. Double bending is often necessary for
web offset presses. In this case, Mitsubishi Paper advises the use
of a NELA Ternes bending unit.
Fig. 4)
NELA Ternes Polyform 52
Plate Bender
Fig. 5)
Beil Thermal
Bender TPB-T
12
Fig. 4
Fig. 5
PROOFING-SOLUTIONS AND COLOR MANAGEMENT
2.0
PROOFING-SOLUTIONS AND COLOR MANAGEMENT FOR
SILVER DIGIPLATE
To check and to ensure a good printing result there are many and in part
low cost proof solutions. For this purpose advantageous Inkjet-printers
are offered as well.
2.1
Application of the proofs
a. Process accompanying layout proof or color proof
It gives a survey over color and completeness of the documents.
The utilisation of color management offers advantages, but is not
indispensable.
b. Contract proof or simulation proof
The use of color management allows to originate correction prints
as coupon.
c. Press or screen proof
In this place the utilisation of color management is also
recommendable. Additionally the screened proof simulates
the resolution of the printing process and its influence on the
printing result. In this way it's allowed to make defects viewable,
e.g. Moirés.
2.2
Workflow profiling
To originate binding proofs for the four-color printing process
through color management an ICC-profiling of all involved devices
is necessary:
2.2.1
Printing machine profiling
The profiling of the printing machine
occurs through the printing of an IT8Chart in the own standard (Illus.1).
Consequently occurs the measurement
of the test-chart by way of a colorspectrometer and the calculation of
the ICC-Profile by way of software.
Alternatively the standardized ICC-Profiles for printing from FOGRA, IFRA
etc. can be used.
Illus. 1
13
PROOFING-SOLUTIONS AND COLOR MANAGEMENT
2.2.2
Illus. 2
Proof printer profiling
Starting from the linearization of the proof device through the printing of taper gauges (Illus. 2) and densitometric examination, a tonevalue wedges adjustment will be executed in the SDP-RIP (Illus. 3).
The ICC-Profiling of the proof device happens through the printing of
the IT8-Chart of the proof printer and the measurement by using the
color-spectrometer (Illus. 4)
Illus. 3
Illus. 4
2.2.3
Profiling principles
If the ICC-Profiles describes the color gamut of the printing machine
and the color gamut of the proof device in an accurate mode, the
digital-proof will be much more accurate.
2.3
Usage of the ICC-Profiles on Mitsubishi SDP-RIP
The usage of the profiles in the Harlequin-based RIP-Software will
be controlled by the ColorPro Module. Input-, Emulation- and Output profiles can be defined (Illus. 5).
For generation of a digital proof, based on individual profiles, it's
recommended to use as input-profile the standard-profile from
FOGRA for offset printing or the ICC-profile,
selected and integrated by the manufacturer
(CMYK or RGB). As emulation profile we select
the individual profile of our printing machine.
The ICC-profile of the proof printer is the output
profile.
In the same way ICC-profiles can be processed for
grey-scale- and spot color printing.
Illus. 5
14
PROOFING-SOLUTIONS AND COLOR MANAGEMENT
2.3.1
Different color gamut calculation through Rendering Intents
The SDP-RIP offers the
possibility for illustration
the choice of different
Rendering Intents, activated and configured by the
Color Rendering Intent
Manager (Illus.6).
Hereby it's allowed to
react on technical development trends of imparIllus. 6
tial media productions.
Picture data are stored in an increasing degree as RGB- or LabData in Media-databases (Content Management Systems) and
afterwards provided with output-ICC-profiles for the respective
operation (Print, CD-ROM, Online etc.). These profiled data can be
processed by the RIP-Software for their purpose. Every involved
device can only reproduce a determined part of all visible colors.
These different color-spaces can be transformed by way of four
different conversion methods:
a. Perceptual
This method is particularly suitable for conversion of RGB- in
CMYK-picture-data. The whole color range of the pattern will be
transformed to the color range of the output-device. It's not common with graphics or screenshots.
b. Relative colorimetric
Every hue within the capability of both devices presentable range
will be exactly rearranged. Hues outside of this range will be
converted to the nearest hue available. It's suitable for conversion
of a CMYK in the CMYK of another device.
c. Absolute colorimetric
Corresponding in large parts to the relative colorimetric conversion, additionally the exhibition of a determined paper coloration
will be computed on the output-device.
d. Saturation
This method will be used when bright colors should be
reproduced. Employment fields are presentations and businessgraphics, not often for printing.
15
PROOFING-SOLUTIONS AND COLOR MANAGEMENT
2.3.2
vDot-Plugin 3.04 - integrated RIP proofing solution
The vDot-plugin from Xitron, exclusive tuned for Mitsubishi SDPRIP, refers to the new Epson Inkjet-printer product line Stylus Photo
2100/2200, Stylus Pro 4000, 7600, 9600 and 10600. The variable dot
size and the 6- resp. 7-colors technique
make them to excellent proof-devices.
In the main menu occurs the selection of
the paper type in addition to the related
data for the process, calibration, printerport and color fine-tuning (Illus.7). The
plugin offers the possibility of progressive proofs (1,2,3-colors) and the simulation of the autotypical raster up to 150 lpi
(6o-raster). This raster-option allows to
control the correct screen angle of the
output-data and makes moirées visible.
The supplied ICC-Profiles contain inkjet-media from different
manufacturers. A few Mitsubishi-Inkjet papers are also listed; this
assortment will be continuously enlarged.
2.3.3
Inkjet-Proof materials from Mitsubishi HiTec Paper
Mitsubishi Paper Mills Ltd. is a big acknowledged manufacturer of
Inkjet-papers as well; the German daughter company is MPHiTecPaper Bielefeld GmbH. In the Mitsubishi Paper technical center
Düsseldorf following Inkjet-Media are in use:
Illus. 7
GD 1497 – 140g/sqm, 2-side silk-matt coated inkjet paper for layout
proof, color proof and register control. Advantageous for small run
length on double-side proof systems in the increasing POD market.
G1699 – 150 g/sqm, silk-matt coated inkjet paper for the "legally
binding contract proof". LAB values and media quoin results
according to FOGRA paper class 1,2,4
SM2574 NS – 255g/sqm, silk-matt coated microporous PE inkjet
paper in "natural white". LAB values and media quoin results
according to FOGRA paper class 1,2,4
A current overview of all by MPHiTec-Paper manufactured Inkjet-Media
is available under: www.jetscript.de resp. www.inkjet-media-mig.com
16
PRINTING
3.0
PRINTING WITH SILVER DIGIPLATE
3.1
Print settings
Care is required with the print settings because the water supply
to an SDP plate is not the same as that to a metal plate.
3.1.1
Dampening solution:
We recommend adding Mitsubishi SLM-OD30 or SLM-OD50 dampening solution to the dampening water. Conventional
dampening System: SLM-OD30 3-5%. Continuous-feed dampening
system: SLM-OD30 3-5% or - for reduced-alcohol or alcohol-free
printing - an alcohol-reducing agent.
For the reduced-alcohol printing it is possible to make use exclusively of SLM-OD50. At this pay attention to keep the pH Value in
the pretended tolerance ranges.
3.1.2
Alcohol or alcohol substitutes:
Use the same dosage as for metal plates. If necessary, use Mitsubishi SLM-OD50 to reduce the amount of alcohol.
3.1.3
Setting the press:
Use the default settings, especially for the dampening rollers and
plate inking rollers.
3.1.4
Adjusting the dampening solution:
When the press first starts up, the Silver Digiplate needs more water
than a conventional aluminium plate. During production printing the
dampening solution requirements are similar to conventional plates.
3.1.5
Additional dosing units:
Additional dosing units are available from Varn or Technotrans to
provide presses which feature cooling or winding mechanisms
with an additional dose of Mitsubishi additives.
17
DAMPENING SOLUTION
4.
DAMPENING SOLUTION
Mitsubishi additives are basically unable to control the dampening
solution's pH value. This should lie in the range between pH 4.8
and 5.3, which is favourable for printing.
Dampening solutions with a pH value of less than 4.5 are regarded
as over-acidic. This may lead to the following problems:
• Problems drying the ink.
• Oxidation of metallic inks.
• Shorten durability of the printing-plate.
Dampening solutions with a pH value of more than 7 the dampening solution is to alcaline. This may lead to the following
problems:
• Reduction of the surface tension between the printing ink
and the dampening solution.
• "The ink goes watery", it emulsifies more intensely.
• The plate is susceptible to scumming.
It is also very important to determine the hydrogen carbonate
levels in the water. This influences the pH value that can be attained
by dampening solution additives. Many dampening solution producers,
such as Huber, offer dampening solutions with a hydrogen carbonate content of either up to 250 mg/l or over 250 mg/l.
Mitsubishi additives improve the water-acceptability of polyester
plates and do not have any effect on printing from aluminium plates.
4.0
Dampening solution recommendations
The successive assembling of the dampening solution is
recommended:
*Combifix XL 8054-.. (4%) + SLM-OD 30 (3%) + IPA (10%)
If you encounter any problems with scumming during start-up,
you should use the following composition instead:
*Combifix XL 8054-.. (4%) + SLM-OD 30 (3%) +o IPA (10%) +
SLM-OA2(1%)
If problems still persist during production printing, we recommend adding Mitsubishi additive SLM-OA 1 (1%).
(* When using Combifix, the water quality should be taken
into account.)
18
DAMPENING SOLUTION
For alcohol-reduced printing, they recommend the
following composition:
*Substifix HD 8013 (3-4%) + SLM-OD 30 (3%) + IPA (5%)
The additive SLM-OA 1 can also be used
to reduce the speed
of the immersion roller.
OR SLM-OD 5O (1 -2%) + IPA (5%)
4.1
Troubleshooting (scumming)
4.1.1
Removing ink from the plate:
In the event that ink reaches open spots, it should be removed
using the detergent or using SLM-OH. After the removal of the
ink, please distribute dampening solution on a sponge and
moisten the plate. Do not use plate cleaner for metal plates.
4.1.2
Checking the press settings:
Make sure that the press is set correctly (rollers, etc.).
On printing machines with cooling and winding devices the
dampening solution temperature should be adjusted between
8 - 12° Celsius.
4.1 .3 Using dampening solution additives:
We recommend using the SLM-OA1 and SLM-OA2 dampening
solution additives from Mitsubishi Paper.
SLM-OA1 improves and accelerates water acceptability and
the formation of a thin, all-over film on the ink and the plate.
If you are using an ALCOLOR or KOMORIMATIC dampening
system, you should add up to 1% SLM-OA1.
SLM-OA1 helps to form a uniform emulsion, and acts mainly
on the ink. The effect is similar to that achieved with alcohol
or alcohol substitutes.
SLM-OA2 acts on the plate surface and binds the fountain more
effectively to the non-printing areas.
19
INKS
CLEANING SOLUTION AND PRINT DUSTING POWDER
5.0
INKS
In principle, all inks are suitable for printing from polyester plates.
High-tack inks are especially suitable, as low-tack printing inks are
susceptible to scumming. The ink's tackiness can be established by
tapping it on paper or between the fingers. If an ink adheres
strongly to the paper or between the fingers, it is highly tacky,
and long threads form. If the ink does not adhere strongly, it is
described as short. This resistance on the part of the ink to
cracking is called tackiness.
less tacky ink
produces short threads
tacky ink
produces long threads
For some special colours, the use of more highly pigmented
printing inks has proved very helpful. Using printing inks with a
higher pigmentation, less printing ink can be used in the roller mill
to obtain the same results.
6.0
CLEANING SOLUTION AND PRINT DUSTING POWDER
6.1
Cleaning solution
Use a cleaning solution containing solvents to clean polyester plates
or Mitsubishi SLM-OH. We recommend dampening a cloth with
water and then adding a small amount of cleaning solution.
Vegetable-oil-based detergents should not be used in the roller- or
blanket-washing unit. Such detergents can leave behind an oily film
on the blanket which wears out the pores in the polyester plates,
leading to problems with scumming or smearing.
6.2
Print dusting powder
Basically, there are print dusting powders that contain calcium carbonate and those that contain potato starch or cornstarch. Print
dusting powders that contain calcium carbonate, such as K 4 from
KSL, are not suitable for printing with polyester plates, as this grain
is very hard, and can destroy the polyester plates during the second
run (reprinting). For printing from polyester plates, print dusting
powders containing potato starch or cornstarch are suitable.
20
STARTING UP THE PRESS
For example, the print dusting powder S 5 from KSL is recommended. The grain size depends on the material to be printed. In the
case of coarser print dusting powders (grain size 30 or 45), the
powder consists of potato starch, whereas with finer print dusting
powders (grain size 15 or 20), it consists of cornstarch. Print
dusting powder from the S 5 WL series is not suitable for printing
with polyester plates. This powder contains calcium carbonate,
and is hydrophobically treated in a special process. Print dusting
powders from the S 5 WL series are specially suited for printing
full glossy pages. This powder prevents so-called abrasive surfaces,
which are created if a normal print dusting powder is used for
glossy pages.
7.0
STARTING UP THE PRESS
7.1
Combined dampening Systems (e.g. DAHLGREN, ALCOLOR)
Systems with a combined ink and dampening solution supply on a
single roller are usually connected to a transition roller and ductortype roller (DAHLGREN, ALCOLOR). Dampen the plate before lowering the inking rollers onto it. Use your normal dampening solution.
1) DAHLGREN dampening systems possibly require a manual
moistening with the prepared dampening solution.
DAHLGREN
dampening System
2) The ALCOLOR and other similar continuous-feed dampening
systems have a transition roller that connects the dampening
system and the inking system together. The transition roller
should be switched off.
7.2
Separate dampening Systems (e.g. KOMORIMATIC)
Dampen the plate by lowering the dampening rollers onto it until
it is thoroughly moistened (approx. 30 -40 seconds). Immediately
when the plate begins to glance turn on the ink rollers.
ALCOLOR
dampening System
KOMORIMAT1C
dampening System
21
RECOMMENDATIONS FOR NON-STANDARD PRESSES
7.3
Restarting the press
The restart of the Silver Digiplate is comfortable; the same
methods as described in 7.1/7.2 are recommended.
Oxidation does not occur on polyester plates.
8.0
RECOMMENDATIONS FOR NON-STANDARD PRESSES
Mitsubishi Paper has specific recommendations regarding settings
for many types of press. The presses mentioned here are only
examples. Further information may be obtained from Mitsubishi
Paper or from your authorized specialist dealer (see chapter 9-12).
22
PLATE CLAMPING PROCEDURE
9.0
PLATE CLAMPING PROCEDURE
The instructions below should be heeded, in order to prevent the
SDP plate from becoming distorted:
9.1
Backing sheet under the plate
Use a calibrated backing sheet if necessary. If the press specification stipulates a 0.30 mm thick metal plate and you want to use a
0.20 mm thick SDP plate, you will need a 0.10 mm thick backing
sheet. This sheet must be clamped in the front clamping bar.
9.2
Plate clamping bars
Make sure that the clamping bars are able to fix the SDP material
in position so that it cannot move. Adjust the pressure of the clamping bars if necessary. Mark the plate close to the clamping bars,
in order to check whether it can slip out. If the mark is still in the
same place after the printing process, the pressure applied by the
clamping bars is sufficient.
9.3
Clamping the SDP plates on presses with no
autoplate system
1) The plate is clamped under pressure.
2) Clamp the plate onto the front bar. If the press has a register
system, the plate is fitted onto the register pins. If not, align
the centre of the plate with the centre line on the clamping
bar. Tighten the adjusting screws in the clamping bar, starting
in the middle and working outwards. Make sure that there are
no air bubbles underneath the plate. Avoid distortion of the
plate during clamping.
3) If necessary, insert a special backing sheet with the calculated
thickness underneath the plate.
4) Advance the press until you are able to fit the end of the plate
into the rear clamping bar. A slight tension prevents excessive
play, while too much tension may cause the plate to become
distorted.
5) After you have inserted the end of the plate into the rear
clamping bar, close the latter. Tighten the plate as evenly as
possible with the clamping screws.
23
MULTI-COLOUR PRINTING
NOTE: This process can be used for all sheet-fed offset presses. Take
care not to clamp the plate too tightly. The method is suitable, provided the register tolerance is no more than 100 micrometres.
9.4
Clamping the SDP plates on presses with an autoplate
system
In principle, polyester plates can be used on presses that are
equipped with a semi-autoplate system. There must be no
distortion whatsoever when they are clamped in the front bar,
or the infeed function will not work correctly. At present, 0.2 mm
thick polyester plates are only partially suitable for presses with
multiplate Systems (fully automatic infeed).
10.0 MULTI-COLOUR PRINTING WITH SDP PLATES, TAKING
THE HEIDELBERG PM 46/QM 46 AS AN EXAMPLE
10.1
Basic machine settings and prerequisites
The basic prerequisites for printing from polyester plates are as
follows:
•
•
•
•
•
•
•
•
24
The polyester plates must be the same size as conventional
plates (505 mm x 340 mm).
Design and proof-print a line-forme corresponding to the
size of the run, to ensure that the press is correctly set and
obtain a suitable register mark.
Adjust the blanket to be level with bearer height.
The blanket backing should be shortened at its rear end,
so that it is not clamped in the cylinder canal. It is advisable
to fan out the backing at the rear end.
Adjust the ink rollers for polyester plates (approx. 2.5-3 mm).
Adjust the dampening roller for polyester plates
(approx. 3.5-4 mm)
The polyester plates and plate cylinder should be dry during
plate loading.
Darker ink should always be used in Werk II.
MULTI-COLOUR PRINTING
10.2
Clamping the plates with an autoplate system
Polyester plates on the PM 46 may be clamped in the same way as
aluminium plates. In some cases, it has proved effective to use a
guide such as an aluminium plate when loading the plate, to ensure that the polyester plate is aligned with the register pins. It is
important that the plate does not lie unevenly in the crack in the
clamping bar. This can cause inaccurate register settings.
10.3
Start-up
When the press first starts up, polyester plates need more water
than a conventional aluminium plate. They should therefore be
sufficiently dampened in advance. The following procedures have
proved effective in practice:
Lift the dampening rollers manually for approx. 20-30 seconds.
The normal set-up procedure can then be commenced.
OR
Interrupt the automatic process and print as soon as the plate is
sufficiently dampened.
10.4
Register with polyester plates
After the press has been optimally set for polyester material, a line or
grid forme is printed out to check the register setting. The machine is
correctly adjusted if it is in-register at both the start and end of the
print run. If the press is adjusted properly and is in a good condition,
a very accurate alignment can be achieved. As the plates are subject to
a great deal of pulling when the press is started up, the
use of too few waste paper sheets can lead to inaccurate results. For this reason, a certain number of waste
paper sheets should be printed whenever the register
marks are corrected. It should also be borne in mind that
plates that are filling in because of smearing or scumming will use a correspondingly higher quantity of ink,
and this may lead to register inaccuracies.
25
FOUR-COLOUR PRINTING
11.0 FOUR-COLOUR PRINTING WITH SDP PLATES,
TAKING THE RYOBI 3304 AS AN EXAMPLE
11.1
Basic machine settings and prerequisites
•
•
•
•
•
•
•
•
11.2
The polyester plates must be the same size as conventional
plates (335 mm x 485 mm).
Design and proof-print a line-forme corresponding to the size
of the run to ensure that the press is correctly set and obtain a
suitable register mark.
Packing depth 2.5 mm (blanket 1.9 mm + backing 0.6 mm).
The blanket backing should be shortened at its rear end, so
that it is not clamped in the cylinder canal. It is advisable to
fan out the backing at the rear end.
The pressure of the plate on the blanket is adjustable.
Adjust the ink rollers for polyester plates (approx. 3 mm).
Adjust the dampening roller for polyester plates (approx. 3.5 mm).
The pre-dampening phase should be computer-controlled (adjustable).
Optimising the register printing for Ryobi 3304
SDP gauge film (underlay sheet for the plate cylinder) from
Mitsubishi is recommended for printing from polyester plates.
This gauge film ensures that the polyester plate slides more
smoothly on the plate cylinder during register setting. This
gauge film can be purchased from Mitsubishi or Ryobi dealers.
26
FOUR-COLOUR PRINTING
12.0
FOUR-COLOUR PRINTING WITH SDP PLATES, TAKING THE
HEIDELBERG SM 52 AS AN EXAMPLE
12.1
Basic machine settings and prerequisites
Because polyester plates are more liable to stretch than metal plates,
the press's basic settings must be adjusted carefully. The basic
prerequisites for printing from polyester plates are as follows:
•
•
•
•
•
•
•
•
12.2
Polyester plates for the SM 52 should not be bended.
The length must be 454 mm, i.e. 5 mm shorter than the
aluminium plate.
Design and proof-print a line-forme corresponding to the size
of the run to ensure that the press is correctly set and obtain
a suitable register mark.
Adjust the blanket to be level with the bearer height.
The blanket backing should be shortened at its rear end,
so that it is not clamped in the cylinder canal. It is advisable,
to fan out the backing at the rear end.
The connecting roller between the inking and dampening
systems should be inactivated.
Adjust the ink rollers for polyester plates (approx. 3 mm).
Adjust the dampening roller for polyester plates (approx. 4 mm).
Lateral distribution of the inking rollers must be inactivated.
Clamping the plates with an autoplate system
Polyester plates on the SM 52 may be clamped without thermal
folding on the rear edge. The polyester plate, which is just 5 mm
shorter than a metal plate, is introduced onto the register pins in
the front clamping bar in the usual manner, so that it is in-register. It is important that the plate does not lie unevenly in the
crack in the clamping bar. This can cause inaccurate register
settings. To prevent this, the front clamping bar may be opened
and closed several times using the botton. After this, the clamping
procedure can be completed by computer control.
27
FOUR-COLOUR PRINTING
12.3
Start-up
When the press first starts up, polyester plates need more water
than a conventional aluminium plate. They should therefore be
sufficiently dampened in advance. The following procedures have
proved effective in practice.
•
•
•
•
•
Lift the dampening rollers manually for approx. 20-30 seconds.
The normal set-up procedure can then be commenced.
OR (if the speed of the pan roller is very high)
Bring the press to a constant speed of 8,000 rpm by turning
the feeding device on.
Lift the dampening rollers manually for approx. 20-30 seconds.
The normal set-up procedure can then be commenced.
In presses with adjustable pre- and post-dampening phases, individual settings may be made specially for use with polyester plates.
During short breaks in the printing during the set-up phase,
or when the stack is being changed, it makes sense to leave
the dampening rollers on the plate.
12.4
Register with polyester plates
After the press has been optimally set for polyester material,
a line or grid forme is printed out to check the register setting.
The machine is correctly adjusted if it is in-register at both the
start and end of the print run. If the press is adjusted properly and
is in a good condition, a very accurate alignment can be achieved.
As the plates are subject to a great deal of pulling when the press
is started up, the use of too few waste paper sheets can lead to
inaccurate results. For this reason, sufficient waste paper sheets
should be printed whenever the register marks are corrected.
It should also be borne in mind that plates that are filling in
because of smearing or scumming will use a correspondingly
higher quantity of ink, and this may lead to register inaccuracies.
12.5
Optimize register printing for SM 52
At register problems Heidelberg recommends the employment of
friction clips. These friction clips can be aquired at Heidelberg.
The purpose of the friction clips is to increase the friction on the
back of the printing plate and the lower clamps.
28
FOUR-COLOUR PRINTING
Therefore sufficient support forces can be guaranteed. Using metal plates the friction clips can
remain in the machine without unfavourable
influence on the printing result.
13.0
FOUR-COLOUR PRINTING WITH SDP PLATES,
TAKING THE RYOBI 524 AS AN EXAMPLE
13.1
Basic machine settings and prerequisites
•
•
•
•
•
•
•
Plate size 500 mm x 410 mm.
Packing depth 2.60 mm (blanket 1.9 mm + backing 0.7 mm).
Adjust the ink rollers for polyester plates (approx. 3 mm).
Adjust the dampening roller for polyester plates
(approx. 3.5 mm).
The pre-dampening phase is not adjustable.
The connecting roller between the inking and dampening
systems should be switched off.
Further recommended settings as for the SM 52.
The AAC System offered by Ryobi (automatic dampening solution
quantity control) is not suitable for polyester plates.
In Series 524 Ryobi presses, the dampening roller can be adjusted
so that it remains in contact with the plate during no-load Operation. This setting means that the polyester plate is permanently
dampened during a print break, preventing over-dampening
when the press is restarted. For this reason it's very important that
the transition roller hasn't any contact to the inking system.
The recommendations for the SM 52 can be applied for
register setting.
29
POLYESTER PRINTING PLATES
14.0 POLYESTER PRINTING PLATES ON 4-UP AND 8-UP SHEETFED PRESSES
Even in the 4-up and 8-up printing the polyester plate has
been proven as successful CtP solution. The application with
or without autoplate is possible.
15.0 POLYESTER PRINTING PLATES ON WEB OFFSET PRESSES
The polyester plate can be used in small and middle format
web offset presses in case of prior thermal plate bending.
16.0 POLYESTER PRINTING PLATES ON ENVELOPE
PRINTING MACHINES
The usage of Silver Digiplate has been proven especially on special
printing machines for envelopes. For these types of machines the
polyester plate has to be treated by a thermal plate bender.
General things for chapters 14. to 16.
Mitsubishi and authorised dealers offer corresponding devices for
the above mentioned thermal bending. Furthermore the necessary
know-how for the mentioned printing machines can be obtained
through Mitsubishi.
Through its worldwide very large number of CtP-polyester customers Mitsubishi Paper has not only user knowledge on the described printing machines but also on other printing machines.
Please contact your representative respectively Mitsubishi.
30
TROUBLESHOOTING
17.0
TROUBLESHOOTING
17.1
Exposure problems (at plate production)
Problem
Too much blackening
Probable cause
Overexposure
Remedy
Reduce exposure
Voids in image (fine lines)
Overexposure
Reduce exposure. adjust imagesetter
Some voids in image
Cloudy exposure due
Identify cause of scattered light
Slight blackening of
to scattered light
Underexposure
Increase exposure
Appearance of silver scan lines
Underexposure
Increase exposure
throughout non-printing area
Silver image on edge of plate
Lack of exposure
Ensure image format
at edges
consistent with plate format
Plate not fed evenly
Check plate infeed
non-printing areas
Incorrect reproduction size
Distortion, deviation
17.2
into the imagesetter
Faulty reproduction (causes associated with the processor)
Problem
Probable cause
Remedy
Uneven image
Fluctuations in processing
Check processor, rollers
time in device
and mechanism
Contact with foreign
Check rollers and guides
bodies in the device
for crystallisation
Problems with plate infeed
Check rollers and guides
Scratches
Folds on the plate
17.3
Faulty reproduction (other causes)
Problem
Probable cause
Remedy
Discoloured
silver image
Plate exposed for an extended
time to an intense room
To prevent light penetration,
the plates should be stored
illumination
in a blackprotective case
Fluctuation of laser energy,
Clean, removing dust and
laser radiation
Activator becoming less effective
foreign bodies
Replace solution
Activator temperature too low
Keep solution at 28- 31 "C
Uneven thickness
31
TROUBLESHOOTING
17.4
Scumming problems at printing (Precondition: well exposed printing plate)
Problem
Probable cause
Remedy
Scumming on
Activator / Stabilizer inefficient
Renew solution
the whole
Insufficient ink,
Use high-tacky inks
printing sheet
or ink not tacky enough
Add dampening solution
SLM-OA1 or SLM-OA2
Inking rollers shifting
Prevent shifting
Dampening solution temperature too high Reduce temperature (ideal 8 - 12° Celsius)
Too much varnish or thinner
Filter dirty
Limit to 2-3%
Change filter in cooling device
Incorrect proportion of thinner in
Increase concentration and check for
dampening water
suitability/ check alcohol content
Worn inking rollers
Molleton dirty or worn out
Renew inking rollers
Replace molleton
Dampening water additive not
Change dampening water additive
adjusted to hardness of water
and adjust to water hardness
Insufficient fountain solution fed in
Paper dust
Increase amount of fountain solution infeed
Depends on paper, consider
using different paper
Printing powder
Restrict use of powder,
Scumming
Ink susceptible to emulsification
especially for two print-runs
Use another ink
(staining from
Too much additive
Reduce ink-additive
emulsified ink)
concentration to 3-5%
Too much dampening solution
Excessive concentration of
Reduce dampening solution infeed
Reduce concentration
dampening water solution
17.5
Dirty molleton blanket
Clean or change
Blanket Rollers worn out
Wash with special cleaning
agent or change
Inferior rendering in the printing process
(Prerequisite: well exposed printing plate)
Problem
Probable cause
Remedy
Faulty
reproduction
Activator/Stabiliser ineffective
Inking roller pressure too high
Replace solution
Check inking roller settings
Blanket pressure too high
Adjust blanket to be level with
bearer height
Inking roller pressure too low
or too high
Check and adjust inking
roller pressure
Blanket damaged
Replace blanket
Cleaning agent not completely
Wipe away cleaning residues
removed
from rollers and blanket
Before printing, ensure cleaning agent
has completely dried on blanket
and inking rollers
Dampening solution
contaminated with chemicals
32
Empty storage container
and clean it
TROUBLESHOOTING
17.6
Voids in printing area
Problem
Probable cause
Remedy
Voids at start
Ink tackiness
Use less tacky ink
of print
Processor chemical has run out
Add new processor chemical
Long interruption to printing
Use anti-drying agent,
or advance the press further
(waste paper sheets)
Voids during
Tacky ink
Use less tacky ink
Blanket worn out
or add additives
Renew the blanket
Blanket pressure too high
Improve the blanket-pressure
Molleton blanket worn out
Renew Molleton blanket, possibly
Paper dust
replace by a softer blanket
Depends from paper, possibly
printing
utilize different paper or utilize
an ink binder
Fog
Intermittent voids
17.7
Inking roller pressure too high
Press gear wheels
Adjust inking roller pressure
Repair, or increase
deflected
pressure slightly
Processing chemicals have run out
Add new chemicals
Blanket pressure uneven
Inking roller pressure uneven
Equalise pressure
Equalise pressure
Dampening roller pressure uneven
Equalise pressure
Ink infeed unstable
Adjust ink infeed
Dust or foreign bodies
Dirty blanket used
Remove
Use clean, soft blankets
for etching
for moistening.
Poor ink acceptance
Problem
Probable cause
Remedy
Poor ink
acceptance
Used stabilisator solution
Tacky ink
Replace chemistry
Use less tacky ink
Insufficient pressure between
Increase blanket pressure
blanket and impression cylinder
Paper dust
Clean blanket, consider
using a different paper
Exposed plates were stacked
Dry thoroughly before storing
in a damp condition
during storage
Exposed plates
Store in dark locations,
exposed to bright
preferably in a black case
light during storage
or drawer, etc.
33
TROUBLESHOOTING
17.8
Poor reproduction of screen ruling points
Problem
Probable cause
Remedy
Blurred screen ruling
Faulty unwinding
Correct unwinding
points (duplication,
Plate has slipped
Check clamping bars, if necessary fix spray
Ink not tacky enough
adhesive, adhesive tape, etc., to plate
Change ink
Blanket tension too low
Increase tension of blanket
Excessive pressure between blanket
Adjust pressure
and impression cylinder
Paper curling at edges
Change paper
Electrically charged paper
Change paper
shadow formation)
17.9
Emulsification of ink
Problem
Probable cause
Remedy
Ink emulsifies on
pH value too high
Check pH value, consider replacing
inking roller
dampening solution
Fountain solution infeed excessive
Reduce Fountain solution infeed
Ink not tacky enough
Change ink
Excessive concentration of
Reduce concentration
dampening solution additive
Rollers worn out
Treat with restorative
agent or replace
17.10 Roller-stripping
Problem
Probable cause
Remedy
Ink not distributing,
Fountain solution infeed excessive
Reduce Fountain solution infeed
no ink acceptance
Water too hard
Soften water
Build-up of deposits on paper rule
Rollers worn out
Clean rollers thoroughly
Replace rollers
Excessive concentration of
Reduce concentration
dampening solution additive
34
TROUBLESHOOTING
17.11 Register alignment differences
Problem
Probable cause
Remedy
Register cannot
Plates are not correctly exposed,
Check plate exposure
be aligned
punched and re-punched
and punching
Plates are not correctly
on the plate cylinder
Check whether plates are
correctly on the register bolt,
if necessary remove air enclosures
between plate and plate cylinder
Faulty unwinding
Excessive pressure
Check unwinding
Check pressure adjustment
Paper not flat enough
Change paper
Printing material has
Use paper with a different
wrong machine direction
Blanket backing sheet
machine direction
Shorten backing sheet
is becoming trapped at
rear in channel
Pressure between blanket
and plate cylinder too high
Adjust pressure
Plate clamping bars cannot
Check plate clamping bars,
secure plate
adjust or replace
Contact strips from inking
or dampening rollers to
Adjust contact strips from inking
or dampening rollers
plate too thick
Subject to technical modifications.
All trademarks and registered trademarks are the property
of their owners
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