Archive for the ‘print control’ Category

The popular “Heidelberg Learning tips” inputs on Dampening solutions in offset printing is rendered below for the benefit of readers.

Dear readers, next to the printing plate and the offset ink, the dampening solution represents the third significant factor in offset printing. Perfect print output – even during high print runs – results from the optimal interaction of these system components.

The below articles are intended to help you to develop a general understanding of the dampening solution, its composition, and its application in the printing industry.

Contents:

  1. Dampening Solution and Additives
  2. The Basis: Water
  3. Water Hardness
  4. pH-Balance
  5. pH-Balance und Buffer
  6. Conducivity = μS/cm
  7. Wetting the Plates
  8. Testing Alcohol
  9. Araeometer Readings
  10. Alcohol Drawbacks in Dampening Solution
  11. Preparing the Dampening Solution
  12. Dampening Solution and Print Problems

1. Dampening Solutions Additives

  • Ideally, the dampening solution should possess a water hardness of 8° dH to 12° dH and a pH-Balance of 4.8 to 5.5.
  • The typical dampening solution temperature ranges between 10°C to 15°C.

At the same time, a printer must know that at low temperatures condensation water collects on tubes and in the dampening solution vats, and this may lead to the formation of water droplets.

Dampening solution additives are complex material systems with various components included to promote adequate emulgation and wetting (surface tension).

They are important for pH-Balance adjustment and for stabilisation (buffer systems), protection against corrosion, for a cooling effect, and in avoiding slime formation (biocide).

In view of the wide-ranging and variegated quality of water, selecting the appropriate additive is essential.

2. The Basis: Water

Water found in nature is not clean, rather it contains numerous gasses and minerals. A printer uses tap water as the source material for his dampening solution.  The water’s hardness is measured in appraising the quality of the water, which largely depends on the quantities of calcium and magnesium present.

In any case, the hardness of the water must be calculated before any additives are introduced, since hardness is no longer easily determined in a prepared dampening solution. Test-strips are useful in performing a simple determination of the total water hardness.

Determining the carbonate hardness is accomplished by means of an indicator solution (substances helpful in making measurements are available, for example, from Heyl Bros., Myron L, Merck, Neukum…). At the same time, one should always remember that a measurement only represents a momentary “snapshot”, and that the quality of the water can continue to fluctuate quite dramatically.

Nearly all manufacturers of dampening solutions will perform a water analysis on request.

you can buy the pH Meter from Amazon, by clicking the above image.

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Prelude:

Out of 2, 50,000 printing presses in India, more than three-quarter of them are small-sized printers (SSP) venturing in low value commercial printing segment. These printers are in mystic enterprise world, in which value of their each useful resource is growing, but margins are dwindling thanks to price war in addition to challenges of new technologies and digital economy. It is not a feature Indian print market alone, similar trend is observed globally.

An inclusive and frugal innovation is required to address this complex trivia. It is not about the next big thing, but about making the most of the last big thing. Gandhian Engineering & Indovation will be the key to survival in this complex market.

What is Gandhian Engineering (GE)?

Embracing Mahatma Gandhi’s ideal of “doing More, for Less, for More, (MLM)”, it aims to democratize technology with Affordable Excellence – Giving high quality at affordable prices! It breeds a new kind of innovation coined as Indovation: “Spend less and innovate.”

Optimal utilization of resources & raw materials are key areas to focus in Indovation.

Indovations for small printers segment:

1. 29” Press or 26” Press? Best of both?

Most of Indian/Asian jobs are printed in demy size (19 x 26 inches) or double demy (25 x 36 inches). But for ganging jobs like visiting cards & invitation etc., a 29” press is required. Even though we can a print a 26” (inch) job on a 29” (inch) press, difference in plate size increases cost by more than 5%.

Indovation is to “Change the ink & water forme rollers of the press to 26”(inch) size to use 26”(inch) plate itself thus reducing overall print cost by 3%. When printer requires bigger size (29” inch) to be printed, replacing ink & water forme rollers will suffix. On an average, this increases printer margins by 10% with increased job capability.

Figure 1: By changing roller 12 & 6 to 26", printer can save plate cost

2. Printing trim waste paper with double gripper jobs:

Most B3 presses can run a minimum paper size of 4” (inches) x 6” (inches). When trimming papers for Demy (19 x 26” inches) from 30 x40”inches paper, there will be wastage of 4 x 20”inch. These wastage papers are sold in 30% of paper cost in kilos

By imaging a printing plate with two different jobs like below, in a B3 size press, the customer can print first job in 4×20” for a typical visiting card, invitations imposed for this paper size.

After completing first job, same plate is dismounted and fitted for the second job (gripper edge interchanged). Thus it reduces cost of printing plate for one job and also reduces paper cost by 70%. It is known as “Cutting bits to Commercial Prints”. It increases profitability by 33% in average.

3. Printing in 3 Colors

For a typical commercial printer with a 4 color press, printing 5 color job needs two print passes and hence reduces his competitiveness against printers with 5, 6 color presses. So utilizing the ancient printing technique of converting a CMYK job – CMY using designing software like corel draw will help printer complete the job in one pass. Printing in 3 color means doesn’t compromise the print quality. A very close simulation and quality towards 4 colors can be achieved by proper color management techniques.

This method has been tested and successful in entry level packaging jobs like fireworks boxes and garment jobs. It increases profitability by 16% in average.

Figure 3: A typical garment job, where a 4 color CMYK image will be printed in 3 color CMY combination without compromising print quality

Conclusion:

Indovation in commercial print is a true win-win combination of ‘excellence’ and ‘application’ together. It gives printers ‘affordable excellence to thrive on the powerful combination of scarcity and aspiration. Most of the described Indovations has been tested in real market conditions and getting successfully utilized by the printers.

Color Measurement the Right Way

Quality printing depends on precise color measurement, which makes it all the more relevant to ask why different measuring devices often produce different results. What should you rely on in this case?

Modern color measuring devices are generally based on spectrophotometers, even if they only show densities. This is because of the higher measuring accuracy of spectrophotometry, together with a greater range of available measurement values. The measuring conditions set on the devices therefore not only need to be selected correctly but must also be identical for all devices. The correct setting often depends on the country. Regional associations such as the bvdm in Germany and CGATS in the United States formerly laid down these conditions. Today they are to be found in the relevant ISO standards. Settings can be made for the following values:

Illuminant: This defines the color temperature of the lighting source. For printing, the standard is currently D50, which corresponds to 5,000 Kelvin.

Observer angle: The standard observer angle in printing is currently defined as 2°. This corresponds to the printer’s observation angle in the matching stage.

Density filter: This determines the spectral range that is to be used to calculate the density values for CMYK. Standards “Status E” (= DIN 16536) and “Status I” (= DIN 16536 NB; narrowband) are usual in Europe. “Status T” is used for measuring in the United States.

Polarization filter: Polarization filters eliminate the gloss of wet ink. The wet values therefore correspond almost entirely to the dry density and tonal values.

White reference: The “absolute white” setting is preferred for density measurement in North America. In all other countries, the white reference is “relative.” Paper white is therefore always taken as the zero point here. To match a spectrophotometer to an old densitometer, it is necessary to know the densitometer’s settings precisely and apply exactly the same parameters to the spectrophotometer. Despite identical settings, minor deviations may occur even within a group of spectrophotometers. These are generally due to the quality and design of the sensor and its calibration. Theoretically, every spectrophotometer should be calibrated to absolute white and black. However, in practice neither one exists, which means it is best to use reference values from an independent institution such as the German Federal Institute for Materials Research (BAM) in Berlin. Manufacturers can have a device calibrated here and use this “master device” to calibrate all other devices. The better the measuring device, the narrower the tolerances that the manufacturer defines for the ΔE and density values. And the smaller the tolerances, the greater the measuring accuracy.

To ensure the measuring accuracy remains constant for as long as possible, users are well advised to have devices serviced and calibrated regularly. Heidelberg is the only press manufacturer to offer a software option – the Prinect Net Profiler – that enables printers to personally calibrate almost all new-generation Prinect color measuring equipment, even including colorimetric calibration. This ensures devices are always close to the factory settings and therefore deliver highly reliable results.

It is also advisable to designate a selected spectrophotometer as the “master” in the print shop itself. This ensures maximum measuring accuracy and, ultimately, print quality across several work stations.

Typical distribution of measuring device deviations – the blue dot in the center is the ideal value for the reference device. The grey circle shows the permitted tolerance. The red dots represent the deviation for different measuring devices.

Source: www.speedmasterunbeatable.com

ISO 12647-2 Presswork Procedure

Quite often we get the question of how to achieve ISO-12647-2 standards in press (not for certification purpose ofcourse).  So decided to write down the steps need to be followed.

1. We have to make a test form with linear plates (test form high-res file is with Mr.Saravanan of Heidelberg). A linear plate means, input and output value has to be same. If we give a value of 50%, the plate should have 50% only (+ or – 1% tolerance)

2. Print this linear plate in the press with the pre-requisites below with varied densities across the sheet

3. After the print is allowed to dry 3 hours, measure the sheet and find the optimum density for the press using Delta E and Contrast method.

4. Then print another test chart with the calculated optimal density (linear plate) and calculate the dot gain deviation.

5. The dot gain deviation has to be calculated and compensated in the RIP as per ISO 12647-2 standards

6. The same test chart to be printed with revised dot gain curve

7. The iteration should continue until the best results are achieved as per ISO 12647-2 standards

8. The Pre-press need to be set as per the “ISOcoated V2.icc” and proof need to be FOGRA 39 standard in V3 media wedge.
Pre-Requisites:

But to do the above exercise, we need to have the below

• Should have a densitometer and also a plate (Calibrated one. Prefered instruments are Ihara R730, Techkon Spectrodens for press and Ihara Accudot or Techkon spectroplate for plate dot measurement)

• you need to print minimum of 3000 sheets of your full paper size of 115/135 gsm art glossy paper with Fresh CMYK ink in the inking unit. When the target is the ISO 12647-2 standard, the used ink series should be ISO conform. Values given below for reference. We can check Ink manufacturer for the confirmation.

• The printing press has to be in a well maintained condition

• Blankets need to be in a clean and proper condition

• New blankets should be washed with water and cleaning solvent

• Verify the blanket tension with a torque key (for tension values check the machine manual)

• The Packing has to be done as per the standards

• The Pressure between blanket/plate have to be in a range of “kiss print”

• The Pressure between blanket/substrate have to be in a range of “kiss print”

• The Ink deck have to be washed clean

• All rollers have to be well adjusted

• Ink- /dampener rolls have to be well adjusted especially to the plate

• The ink distributor roller have to be checked

• Verify the machine manual for adjusting the rollers according to the machine manufacturer

• The pH-value of the fountain solution should be at a level between 4.7 – 5.3

• The percentage of alcohol in the dampening solution should be at a level between 5 – 10%

If you have any doubts are clarifications, please feel free to come back to us colorsherlock@live.com

 

History of Color management in operating systems

The most efficient approach is to integrate the color management system into the computer operating system.

Here, every color can be processed neutrally in the computer irrespective of the input or output medium. All the hardware and software components involved in the system can access color management because they all collaborate with the computer operating system.

In April 1993 at the initiative of FOGRA (Forschungsgesellschaft Druck e.V.), several manufacturers of devices and software in the color graphics sector decided to form a committee with the aim of defining and standardizing various cross-platform device profiles for gamut mapping.

The name of this committee is the ICC (International Color Consortium). The ColorSyncR 2.0 system add-on by AppleR, launched onto the market in spring 1995, was the first example of a color management system based on Linotype-HellR/ Heidelberg

technology being implemented in an operating system. The same technology was used at a later date for Microsoft Windows operating systems.

You will find what is known as the Color Matching Module under the term ICM in the operating system under Windows 98, SE, 2000 and XP.

Source:Heidelberg

Pre-flighting is a term used in the printing industry to describe the process of confirming that the digital files required for the printing process are all present, valid, correctly formatted, and of the desired type. The term originates from the pre-flight checklists used by pilots. The term was first used in a presentation at the Color Connections conference in 1990 by consultant Chuck Weger.

Source: everydaycolormanagement.jap

PDF troubleshooter

These are the TOP 10 problems when using PDF in graphic arts. Don’t take my word for it, this list actually comes from Adobe.

  1. The resolution of images is too low.
  2. Fonts are not embedded in the PDF.
  3. The wrong color space is used.
  4. The information about trim or bleed are incorrect.
  5. There is an inconsistency with the native file. The original page, as viewed in QuarkXPress or InDesign or whatever other application looks different from the PDF. Hairlines might be different or gradients have changed.
  6. A spot color is misnamed or it is accidentally converted to a process color.
  7. Images are compressed too much. This causes a quality loss and in some cases artifacts appear inside or around the images.
  8. The page size is incorrect.
  9. There are problems with transparent objects.
  10. ICC profiles are missing or incorrect.

One of the reasons why many of these problems go undetected is that designers have the habit of making proofs from their lay-out, checking those proofs and then creating PDF files. These PDF files don’t get looked at, they are sent straight to the agency or printer. It would be far better if designers created PDF files and then made a proof of these files. This way the consistency between supplied file and proof is much better!

Next to PDF files having some kind of issue, it can of course happen that a PDF cannot be ripped or rendered at all. Here are some typical things to try when this happens:

  1. Use PitStop or another tool to get rid of any irrelevant data in the PDF file. Delete OPI comments, forms, scripts, animations,… and then use ‘Save As’ to create a new clean PDF file.
  2. Refry the PDF file if you don’t have access to the source file(s).
  3. If you have the source files, try recreating the PDF using a different procedure: if the problem file was creating by exporting to PDF, try creating a PostScript file and distilling that. If the problem file was created using Distiller or Normalizer, try using ‘Export to PDF’.
  4. If you have access to the source file: clean it up and recreate the PDF: Make sure that any spot colors that are not printed as spots are converted to CMYK in the original file. Delete any unused data (stuff on the paste board, elements hidden underneath others, unused pages,… )You also may want to merge layers, paths or channels. Then do a ‘Save As’ to create a clean source file.
  5. If everything else fails, try opening the PDF in Photoshop and saving it as an image. This operation converts all text to bitmap so it really has a huge impact on the quality of the output but if everything else fails, this is your last resort.

Source:prepressure.com