Techniques of instrumental analysis have been increasingly indispensable for technical development of all industries. Within the print industry, these techniques are used to solve problems pertaining to the printing process. In this review, two types of analytical cases are introduced. One is the analysis of foreign contamination of paper and the other is the evaluation of ink penetration in paper. Typically, the most suitable analytical instrument must be selected in order to obtain appropriate information in less time. However, in some cases, it is necessary to analyze the results obtained from several analytical instruments to estimate the information comprehensively. Finally, we need to evaluate the data from multiple viewpoints so that the huge data obtained from instrumental analysis do not confuse us.

View full abstract

Surface inspection for manufacturing a PS-Plate uses mainly two types of systems. The laser-beam scanning-type surface-inspection system is able to use safety light for the PS-Plate to choose wavelength. This system is in use for long as it can inspect plate defects as well. The other surface-inspection system is the CCD camera-type. Its performance has improved with CCD pixels and the increasing speed of central processing unit (CPU) nowadays. The inspection system has developed for new type PS-Plates; CTP (Computer to Plate) and the Environment-friendly Process-less plate. The systems employ new image-processing technology and equipment using polarization characteristics. This article gives an introduction of the constitution and mechanism of the surface-inspection equipment along with its features.

View full abstract

X-ray micro computed tomography (μCT) is imaging of X-ray in three-dimension (3D) on a smaller scale and quite higher resolution than the method used in clinical CT scans. It represents 3D microscopy, wherein the internal structure of an object is imaged in a fine scale non-destructively. Using non-destructive method can create realistic visual models for virtual travel within the object and for the measured 3D morphometric parameters at a micron-level spatial resolution. In this article, we explain the principle of X-ray μCT, which includes the theory, instrument configuration, and some unnecessary artifacts in the 3D images. In addition, we demonstrate the applications of the method on paper, standard postcard, and glossy paper used for photograph printing for a comparative study. The differences in the internal structures of the papers were clearly observed; they were visualized using laboratory-based μCT scanner under high-resolution scanning condition. We conducted quantitative analysis of microstructures, which were distributions of crack-width and particle-volume in the glossy paper. Based on this X-ray μCT analysis, which is the non-destructive imaging of internal structures of materials, we hope that research and development of materials will dramatically accelerate for applications in broader fields.

View full abstract

Infrared (IR) and Raman spectroscopy are important tools for identifying unknown substances and evaluating their physical properties. In recent times, due to eventual improvement in their performances and development of their accessories, they are used as important analytical tools in many fields. These spectroscopic methods are invaluable because they can detect molecular bonds or lattice vibrations directly, which are important for identifying the chemical structure of a sample. In IR spectroscopy, the absorption of a sample is detected, which comes from excitation of molecular vibration. On the other hand, in Raman spectroscopy, the Raman scattering light is detected, whose wavelength is different from that of the irradiated laser. In this paper, these two vibrational spectroscopic methods are discussed and their several applications using for the printing industry such as foreign material analysis, micro-FTIR imaging, micro-ATR imaging, stroke-order appraisal and microanalysis of pigment using resonance Raman spectroscopy, are highlighted.

View full abstract

Light-scattering technique is a useful tool to characterize a nanomaterial. It provides us the information about particle size, zeta potential and absolute molecular weight of the nanomaterial. In this report, light-scattering method was applied for evaluation of the dispersion and stability of printing materials. Current techniques can measure the particle size and zeta potential of printing ink without dilution, which may change its physical property. Commercial inks are all mono-dispersed and largely negatively charged. Excellent mono-dispersity and negatively charged state of commercial ink contribute to high-definition printing and long-term dispersion stability respectively. It is also important to effectively evaluate a detergent, which promotes the dispersion stability of particles. Additionally, light-scattering technique can be applied to the evaluation of plate-shaped materials. The surface potential of a paper and that of a film is related to the fixing of coloring matter or coating agent. Furthermore, the measurement of pH dependence of the particle size and⁄or zeta potential gives us information about the stability of printing materials.

View full abstract

In music printing, some steps of engraving, such as layout, marking, etc., were believed to have succeeded from initial lithography processes. Music printing by engraving in the beginning of the 19th century was studied to clarify the backdrop technique of lithography, by using a music score from the Ludwig van Beethoven's piano sonata no. 21 opus 53, which was printed by the Bureau des arts et d'industri in Vienna in 1805. By analyzing the score, some engraving techniques in music printing could be clearly understood, i.e., punch patterns of music note, order of patterning, rough positioning of notes, re-cutting of lines, corrections of note, etc. Ledger lines were undetectable in the plate-making technique.

View full abstract

Tolerance range for skin color variations has been mostly studied in color reproduction of photography and real human faces. As animations have become more popular in recent times, it is important to study the tolerance range for skin colors of character faces in animation images. We recently reported that face shapes influence the skin colors of faces in animation images (Han and Uchikawa, 2016).In the present study, we focused on dependence of the tolerance range on background scenes. In the experiments, the observer estimated skin colors of a character face, which were presented on various backgrounds in a cascade procedure. It was shown that the tolerance range of skin colors was dependent on the background parameters, more specifically, indoor and outdoor scenes, color temperature and level of illuminance in the background. Color constancy index (CI) indicated that effects of color constancy were smaller in animation images than natural ones. Lightness constancy index (LI) was different that depends on color temperature of the background scene. Therefore, tolerance for skin color variations and preferred skin colors in animation images clearly depend on the background.

View full abstract