Process Inks Research Articles

Investigating the agreement between polarized and unpolarized densitometry in offset lithography printing

AbstractAutomated color measurement systems have become significant components of offset lithographic printing presses for better process control and reduced job waste. Some European press manufacturers are known to offer automated color measurement equipment that is confined to polarized density readings, which is uncommon in US. Introducing polarized densitometry into an environment where unpolarized densitometry is utilized can be problematic. Print professionals are on the lookout for a solution that is evidenced by a recent feature in a post from the IDEAlliance G7 Professionals forum seeking for a methodology to convert polarized to unpolarized readings. The present study applies the Bland–Altman method together with other statistical analyses to determine if a conversion between polarized and unpolarized densitometry can be established within a limited set of parameters. Three spectrodensitometers were used to record densitometric readings of wet and dry process inks on coated and uncoated drawdown proofs. The results showed that coated papers had significantly less variation between instruments compared to uncoated papers. Wet inks had more minor variations compared to dry inks. Furthermore, pure difference values and a Mann–Whitney U test indicated differences between unpolarized and polarized densitometric readings in all cases. Finally, t‐tests performed on the resulting difference data for both unpolarized versus polarized and unpolarized versus predicted polarized that showed fixed bias by means of the computed p‐values.

The Amber Project: A Survey of Methods and Inks for the Reproduction of the Color of Translucent Objects

Unlike regular pigments based on selective light absorption, the so-called “effect pigments″ are based on the phenomena of structural color, or selective reflectance. Structural color has appealing aesthetic qualities, such as angle-dependent hue, and is able to produce lightfast colors. When used as a pigment, however, the gamut of the print is more limited, the color is difficult to measure, and therefore color management and preprint process become challenging. The aim of this paper is to compare the behavior of effect pigments in the processes of lithographic and screen printing with standard pigments used in so-called process inks, and to analyze their optical properties when used on their own or in combination with absorption pigments. An image of amber beads was printed as screen prints and lithographs. Three sets of inks were used: Set one: Standard process inks in the colors cyan, magenta, yellow and black (CMYK); set two: RGB inks formulated with Merck Spectraval™ pearlescent pigments which allow additive red, green, blue printing on a black substrate; and set three: golden inks formulated with pigments from the Merck Iriodin™ and Pyrisma™ effect pigment range. The image was printed on white and black paper. The optical appearance was assessed visually, and spectra and color coordinates were measured.

Investigation of Curing Silver Conductive Inks on Fabrics Using DLP Projector and Hot Plate

This study is to investigate the curing of silver conductive ink tracks on fabrics using a combination of direct light projector (DLP) and hot plate since conventional curing process using laser and oven suffer from several weaknesses mainly costly process and warping defect. The fabrics used are made from nylon and polyester while silver conductive inks were used for the entire study. Samples were made by coating the fabrics with rubber dye inks using silkscreen process and conductive inks were manually laid out on top of the rubber dye according to the designated pattern. A Microsoft power point slide is used to shape the light image on top of the hot plate where the sample is located. Variation of curing time and temperature with constant curing distance were investigated. Several mechanical and electrical tests were conducted to determine the cure, hardness, adhesion and resistance level of the ink tracks. The results obtained were as expected which the longer curing time taken and a higher temperature used, a lower resistance is produced. It is proven that a combination of projector and hot plate is capable of curing the ink tracks properly, a cheap process and easy to handle.

Infrared steganography with individual screening shapes applied to postage stamps with security features

Original scientific paper Designing a postage stamp requires positioning of graphic security elements in a limited small format, so the design is made for two states: for the visible spectrum and the infrared spectrum. Individual screening elements are introduced as security elements in the steganography of invisible pictures in the 700 to 1000 nm spectrum. The CMYKIR theory of hiding the infrared message in the picture is extended by mixing process inks with the control of spot twins of the same colour tone in the X0 and X40 states. Two pictures are integrated in the security print; a multicolour picture visible to the naked eye, and another hidden picture visible when illuminated with an IR detecting instrument. The CMYKIR method is joined with the new element’s algorithm used for dispersing of the hidden picture’s (Z picture’s) fringes. This kind of steganography is applied in the design of postage stamps and it is a new way of securing them.

Gamut evaluation of an n‐colour printing process with the minimum number of measurements

AbstractThe aim of this study was to use a minimum number of measured colour patches to evaluate the colour gamut of an n‐colour printing process. Traditionally, the colour gamut of a printing system has been derived by printing and then measuring a gamut target for example, a profiling chart. For an n‐colour printing (printing with more than four process inks), it is desirable to know the colour gamut of the given set of inks without having to print a large number of test patches. Different spectral printer models were used to predict the gamut of a 7‐colour printing process. The colorant space was divided into sectors each containing four inks. For each printer model, the colour gamut of the each four‐ink sector was predicted. All sector‐gamuts were then combined to predict the overall colour gamut of the n‐colour process. This predicted gamut was then compared with the gamut obtained by measurement using a gamut comparison index (GCI). The Yule–Nielsen modified spectral Neugebauer (YNSN) model gave the best accuracy, at the cost of a larger number of input measurements, than other models. A combination of the Kubelka–Munk (KM) and YNSN models performed well with the fewest input measurements. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 408–415, 2015

Effect of oil based CMYK process inks on tearing characteristics of paper

Gunluk yasamda yirtilma direncine maruz kalan bircok baskili malzemeyi kullanmaktayiz. Kâgit ve baski murekkebi arasindaki etkilesimler lifler arasi baglari ve dolayisiyla kâgidin yirtilma direncini etkiler. Bu calismada Cyan, Magenta, Sari ve Siyah renk yag bazli ofset proses murekkepleri kullanilarak yapilan zemin ton baskilarinin kagidin yirtilma direncine etkileri belirlenmeye calisildi. Kâgidin statik yirtilma direnci, evrensel cekme testi cihazi kullanilarak belirlenmistir ve yirtilma direnci modelleri incelenmistir. Basili kâgitlarda yirtilma direncinin azalmasi ve nispeten yakin yirtilma endeksi oranlari (capraz yon/makine yonu) gozlemlenmistir. Yag bazli murekkeplerle zemin tonlu baski uygulamasi, kâgitlarin yirtilmaya baslamasi icin gerekli olan gucu arttirmistir.

A Print Performance Study of the Environmental Friendly Wide Gamut Process Inks

To expend the printed color gamut is the most important area for today’s print quality. Conventional wide gamut printing technologies utilize six or seven colors. However, these processes increase the complexity and the cost. Therefore, the four-color wide gamut inks are becoming the major development in Taiwan’s printing industry. This study is focused on the print performance study of the four-color wide gamut inks in the domestic market that are complied with the RoHS regulations. In this study Tung-Ming and K+E wide gamut process inks were tested for their print performance. The press control was to comply ISO12647-2 specifications. The test forms were printed on both type 1 and type 2 papers that specified in ISO12647-2. The normal process ink set was also printed to compare with those wide-gamut color ink sets. The result shows that the both wide-gamut ink sets have reached color gamut larger than the ISO12647-2. In this study shows that the domestic normal process ink set can comply the international standard, and the developing wide gamut ink also reach the standard. However, the color characteristics and printability have to test before using these wide gamut color ink sets. With the optimized process control and color management system, the four-color wide gamut inks can produce the best color result on paper.

Study on the Applied Performance of Color Inks

In order that a better analysis and evaluation of the color performance of developed color inks according to the printing requirements could be obtained, every ink will get abundant levels of ink supply amount made by double-channel control method. The max density obtained by the above method represents the color strength of inks. Then Color Management System is applied to building color gamut of matching process inks, and the color gamut represents the replicable color scope in practice. First, color strength of inks was identified by the following methods. Every ink was put respectively in two ink channels of the color printer and the total values of these two channels were applied to controlling the output, obtaining the wedge diagram of the multilevel output of ink supply amount. In the diagram, the max ink supply amount was large enough and the max density could represent the color strength. Because every ink needs a suitable range of the max density and needs to match the others well in practice. Referring to the standard of offset printing, a suitable density value for a certain ink was chose as its max ink supply amount. Second, within the range of the max ink supply amount, the data set of color patch in the characterization software of Color Management System was used to control ink supply amounts. The color patch was overprinted in the color sequences of Y, M, C and K, and ICC Profile was made according to the making process of standard Profile. Color gamut of the inks could be obtained from the Profile by using self-developed computing equipment and be compared with standard printing process. The result shows that the method used in the experiments is feasible and effective. In addition, the inks in the experiments have a large enough color strength and a color gamut satisfying the practical requirements of the color performance of inks in the printing industry.

Digital reconstruction of halftoned color comics

We introduce a method for automated conversion of scanned color comic books and graphical novels into a new high-fidelity rescalable digital representation. Since crisp black line artwork and lettering are the most important structural and stylistic elements in this important genre of color illustrations, our digitization process is geared towards faithful reconstruction of these elements. This is a challenging task, because commercial presses perform halftoning (screening) to approximate continuous tones and colors with overlapping grids of dots. Although a large number of inverse haftoning (descreening) methods exist, they typically blur the intricate black artwork. Our approach is specifically designed to descreen color comics, which typically reproduce color using screened CMY inks, but print the black artwork using non-screened solid black ink. After separating the scanned image into three screening grids, one for each of the CMY process inks, we use non-linear optimization to fit a parametric model describing each grid, and simultaneously recover the non-screened black ink layer, which is then vectorized. The result of this process is a high quality, compact, and rescalable digital representation of the original artwork.

Toyo Ink announces new high-density process inks for newspapers

Toyo Ink announces new high-density process inks for newspapers

Readability of Processed Digitally Printed Two-Dimensional Codes

Despite the evident success of conventional one-dimensional (1D) bar codes and their role in automatic product identification, logistics, supply, and retail, these 1D technologies can encode only a limited amount of data and are susceptible to damage and obscuration. On the other hand, two-dimensional (2D) codes which began appearing in the 1980s are becoming more and more popular because of their ability to encode a large amount of data in a small area. They can also be read even if they are partially damaged or erased. Because of their advantages in comparison to linear bar codes and their increasingly frequent use the authors analyzed two 2D codes (DATA MATRIX code and QR code). The purpose of our research was to determine the lowest raster tone value for each printing color and each printing technique which would enable the 2D code reading with two different readers. For testing the readability of codes, lightfastness, accelerated aging, and water resistance were used. Codes were created and printed in four process inks (cyan, magenta, yellow and black), each of them in the following raster tone values: 15%, 20%, 25%, 30%, 50%, and 100%. Samples were printed using three different digital printing technologies (ink jet, laser, and magnetography). After printing, the samples were illuminated by Xe light, exposed to accelerated aging (at 80°C and 65% relative humidity) for six days, and immersed in water to determine their water resistance. All printed samples, before and after illumination and accelerated aging, were read with laser and charge coupled device based readers, and the lowest raster tone value of the code for each printing technique and each printing ink was determined.

Image Reproduction for Near Infrared Spectrum and the Infraredesign Theory

This aticle presents results of a study of color separation for the near infrared wavelength area in case of a double image reproduction. One image is observed in the visible spectrum (VS) and another one is detected under near infrared (nIR) light. For the purpose of nIR separation (CMYKIR), discussion is extended to CMYK working space as a device dependent for comparing several printing technologies. CMYK process inks characteristics enable visualization of the same color tone in default color settings with the goal to create two independent images in the same print ; two independent pieces of information recognizable under two different types of lighting. The new approach to image reproduction is based on the idea of controlling and processing several images incorporated into one reproduction. This article unites five principles which are set for processing near infrared image reproduction: the range of CMY into CMYK transformation, CMY invisibility in near infrared light, carbon black in nIR, gray and CMY gray and device dependency of CMYK inks. The reproduction is observed selectively in wavelengths ranging from 400 nm to 1000 nm. Independent graphics may be graphics generated by algorithms, conventional images or texts. Information about its visible area is joined to each graphic. Detecting graphic work incorporated differently in a print with the help of the corresponding instruments is becoming a new chapter in security graphics, design and informatics.

CMYKIR security graphics separation in the infrared area

Graphic printing inks respond in different ways when they are in the wavelengths of a near infrared (IR) area. It is not possible to measure such response in the IR and describe it with parameters from the CIELab, sRGB or HSB color systems that are the base for color theory in the visible spectrum area. Additive RGB colors that we use to describe the image in our eye correspond with subtractive C 0 M 0 Y 0 printing inks used for nearly overall printing reproduction in the overall color visual spectrum. Adding of black color ink that has a good response in the infrared area, and subtracting CMY inks makes it possible to carry out each color tone in an endless number of ways. CMYK printing ink characteristics are the basis for setting the algorithm for double appearance of independent graphics: the first graphic in daylight and the second “IR graphic” in infrared light. Proposed algorithm creates a print X on the base of two pictures: the original one X 0 and mask F. The aim is documents’ ultimate security which is detected in IR area. Graphic element visibility with the help of instruments in the wavelength area from 700 to 1000 nm allows programming the selection of image information by using process inks only. The individual characteristics of those printing inks are used for introducing a new criteria in the RGB/CMYK separation process with the goal to create IR graphics. We call this separation CMYKIR and use it for planning the dosing of inks in the creation of good quality reproductions with incorporated IR characteristics: either for causing or prohibiting the IR effect. The goal of CMYKIR reproduction is to incorporate the set “IR graphic” that is not meant to be detected in the visible spectrum part.

Separation model of colour regions in a halftone print

To evaluate print characteristics on the basis of scanned microsamples of printing sheets, it is necessary to carry out the segmentation of particular colour regions, printed with process inks. The accuracy of the evaluation of print characteristics strongly depends on the successful segmentation of the colour regions involved in a print sample. The first step of segmentation must be the separation of the specific colour from a multicolour sample. This paper describes the method of colour separation based on the evaluation of differences between the colours involved in the print sample. The result of the separation process is a monochromatic image, which is further processed by segmentation methods to gain accurate regions of specific colour or regions of halftone dots.

Drying of Water-Based Inks on Plain Paper

Previous studies in ink-jet printing have considered ink penetration into paper or ink evaporation to be effective in the drying process. In the present study, a unified approach that allows for simultaneous evaporation and penetration during the drying process was applied. To this end, penetration rates were measured experimentally using a Bristow tester. In addition, evaporation rates were determined from a theoretical evaporation model that contained no adjustable parameters. It was found that for plain paper used in the office environment, the rate of penetration was at least 20 × higher than the rate of evaporation. Accordingly, ink drying is determined mainly by penetration, and penetration curves alone are sufficient to predict the dry time or ink disappearance on a plain paper surface. In practice, this is illustrated by ink-jet print quality on plain papers of various sizing treatments. The sizing level needs to be adjusted according to the desired ink-jet image. That is, full-color printing requires penetration rates sufficient to accommodate each of the process inks applied without color bleed or other ink-to-ink interaction processes. This may be at expense of character and line print deterioration due to fiber swelling in mono-color printing.

ALLERGIC CONTACT DERMATITIS TO ULTRA VIOLET CURED INKS

Two employees of a factory using an automated screen printing process and ultraviolet cured inks to print onto plastic bottles developed an allergic contact dermatitis, principally on the face and periorbital areas. On patch testing a contact allergy was found to the ultraviolet cured ink UV 50-85, and its multifunctional acrylic monomer component, tripropylene glycol diacrylate.

The Development of Process-Printed Munsell Charts for Selecting Map Colors

Color charts aid cartographers in the difficult task of choosing color schemes for maps. The perceptual organization of Munsell charts presents many potential color schemes. The colors on Munsell charts, however, are painted and many maps are printed with process-color inks. Combinations of process inks (percentages of yellow, magenta, cyan, and black) that approximate the Munsell organization are developed using color measurement followed by systematization of percentage progressions and visual adjustment. Diagonal arrangements of progressions of ink percentages approximate the perceptual organization of the painted Munsell charts. Value and chroma progressions and constancy of hue on ten printed Munsell chart are shown to be acceptable by measuring and mapping discrepancies between the original and printed colors.

People

Sir Robin Napier has been appointed as a non‐executive director of Dane & Company Ltd, the specialist manufacturer of screen process inks and Day‐Glo® daylight fluorescent colours.

Lithographic process inks

As presses become more sophisticated, the more compatible the inks that feed them must become and this is reflected in the changing attitude that printers have adopted to process inks in recent years. The market now looks upon process inks as a ‘commodity’ item which can be put on the press to run consistently and efficiently without any attention. Like oil in an internal combustion engine, process inks have become an integral part of the machinery and are an important factor in a printer's ability to achieve high efficiency.

Relationship between Paper Qualities and Color Reproduction of Prints

Evaluation of prints is finally performed by vision. However, we confirmed that the GATE system which is used for checking of the color of process inks in the ink industry is useful for that purpose. Then, we examined that how paper qualities influenced to the values of the GATF system.In the all literatures on this problem, discussion has been done covering wide range from art paper to low grade paper. Hence, the authors have missed the evidence that a paper quality of each kind of paper influences differently to the color reproduction.This paper is a report on fine paper. We found that the gloss, the oil absorbability, the light scattering ability, and the color specification of a white color of paper, in the order of increasing, give influence to the color reproduction. The color specification is a main factor. We proposed a new equation to indicate the color specification of a white color of paper. Using this value, we can estimate the color reproduction of prints which is influenced by a white color of pulp or effect of a whitener.