Search

Even though most information is digitized today, paper as a printing substrate is still essential. The quality of the paper depends on whether it has the properties required for its intended use, which will fundamentally rely on the raw materials used. Nowadays, the production of paper and board is increasingly focused on alternative non-wood raw materials. In this context, the main objective of this research is to improve the quality of prints on laboratory-made papers with supplementary barley pulp by coating the surface of the papers with titanium dioxide coating. Since laboratory-made papers were not subjected to the bleaching process and no additional surface treatments were used, TiO2-based coating proved to be one of the ways to improve the quality of the prints on such substrates. In this study, it was concluded that TiO2-based coating did not affect the colorimetric values of the black prints to the extent that it affected the colorimetric values of the magenta prints. However, density of printed inks was increased up to 14% for prints on laboratory-made papers with higher amount of barley pulp and TiO2-based coating in two layers.

Objectives The development and placement of translucent zirconia ceramics on the dental materials market is in full swing. This research aimed to investigate how aging protocols affect the microstructure, color parameters and translucency of a new-generation monolithic zirconia ceramic. Material and methods Translucent zirconia ceramics KATANA-Zirconia STML with different surface treatments (as sintered - control, glazed, polished) was tested using two aging protocols (hydrothermal degradation in autoclave at 134 °C and 2 bars for three hours, chemical degradation in four-percent acetic acid at 80 °C for 16 hours) in order to examine phase composition using X-ray diffraction analysis and ΔE, ΔL and ΔC color parameters through spectrophotometry. The translucency parameter (TP) was calculated using parameters L*, a* and b* on a black and white surface. Results Regardless of the surface treatment, aging protocols did not cause a tetragonal-to-monoclinic phase transformation, although hydrothermal degradation in the autoclave transformed the hybrid tetragonal-cubic structure of all specimens to a tetragonal one. All polished and glazed specimens during chemical degradation demonstrated a significant color change ΔE. Lightness ΔL significantly changed in polished specimens aged in the autoclave. In all specimens, ΔC underwent a change manifested through statistically insignificant yellowing. None of the aging protocols altered the translucency of specimens. Conclusions Aging, regardless of the final surface treatment, did not manifest a monoclinic phase in the specimens. A tetragonal-cubic microstructure dominates. Unlike polishing, glazing the surface of translucent zirconia ceramics contributed to minor changes in color, lightness and chromaticity. The translucency of translucent zirconia ceramics remains stable regardless of aging and surface treatment.

Purpose This paper aims to highlight the importance of braille for visually impaired people and the possibility of printing it by using the ultra-violet (UV) inkjet printing technique. Design/methodology/approach The vision impairment, definitions and statistics, as well as braille letter and standards, are first reviewed. Then, the methods of printing braille have been discussed, with a focus on UV ink-jet printing. Finally, this study indicates a significant role of UV ink-jet printed Braille, its possibilities and its advantages. Findings Research studies in the field of UV ink-jet printed braille are showing that it is possible to print good legible braille of the adequate height of dots. This paper highlights some advantages of printing braille with UV ink-jet, like the possibility of achieving greater dot height than embossing and no need for printing form. Printing of additional elements on top of braille dot has also been tested, and possible use for differentiation of the written notation is shown. This paper also indicates the importance of technological and operating conditions in UV inkjet braille printing. It predicts a significant role of UV inkjet in braille printing. Originality/value This paper provides a detailed review of UV ink-jet printed braille: possibilities, advantages and application.

Considering that optical properties play a very important role in the printing industry, this research focused on analysing the optical properties (opacity, whiteness, brightness and yellowness) of laboratory made papers from recycled wood pulp, with the addition of different straw contents, coated with titanium dioxide white ink. Titanium dioxide white ink was applied on laboratory papers to achieve optical characteristics as those of commercial papers recommended by ISO 12647. All the coated laboratory papers presented whiteness within the recommendations of the standard. Almost all the coated papers made with the addition of straw pulp achieved satisfactory optical properties, especially those containing 10% and 20% straw pulp. Coated laboratory papers containing 10% and 20% wheat pulp were comparable to commercial paper and reached a similar value of brightness, while their opacity and yellowness values were even better than those of commercial paper. In order to preserve the natural appearance of papers made with the addition of straw pulp, it is possible to conduct selective white printing as background for high-quality printing.

In order to achieve high-quality colour prints by using an electrophotography (EP) printing machine, it is necessary to prepare the printing substrate. Additional treatment may be needed to achieve better substrate surface tension for optimally attaching the liquid EP ink to the paper. To ensure good adhesion of the ink to the printing substrate, a corona treatment may be used. During the corona treatment, the surface of the paper is modified, and the ability of paper to accept the ink is improved. In this study, we will determine the possibility of realizing CMY prints and of achieving an increased range of tone value in EP digital printing. Based on the results, the new possible values of reproduced CMY tones will be determined, so that higher print quality can be achieved. The results show that the best colour reproduction is achieved without the use of corona power (0 W). The additional activation of 450 W corona will result in the greatest colour variation of ∆EC = 0.60, ∆EM = 0.60 and ∆EY = 0.48.

For high-quality black & white printing realized with an electrophotography printing machine, it is necessary to prepare the printing substrate. For optimal adhesion of the black liquid electrophotography ink to the printing substrate, it is necessary to apply additional treatment to meet ideal substrate surface tension by means of corona treatment and/or coating with fluid for regulating the surface tension (primer). This paper examines the influence of the corona power and the thickness of used fluid for the regulation of surface tension on the achromatic digital reproduction quality. Within the electrophotography printing process, this implies determining the differences in the colour gamut volume, the structure of characteristic screening elements, the amplitude-modulated screening, and the increase in the number of colour separations. The results show that the optimal colour tone values, colour gamut, and dot gain, high quality of digital prints will be realized without the use of the fluid for the regulation of surface tension and without activation of the corona power. That confirms that the FOGRA values for industrial standards can be used for quality electrophotography printing.

Objectives: To examine the effect of two aging protocols on the chemical and phase composition as well as the surface state of monolithic translucent zirconia ceramics. Material and Methods: Translucent zirconia ceramics KATANA-Zirconia STML with different surface treatments (no treatment, K1, K2; glazed, G1-G8; polished, P1-P8) underwent testing in order to examine how the two aging protocols (three-hour hydrothermal degradation in an autoclave at 134 °C and 2 bars: G1-G4, P1-P4, and sixteen-hour chemical degradation in four-percent acetic acid at 80 °C (ISO 6872): G5-G8, P5-P8) affect chemical composition, particularly the share of stabilizing yttrium oxide (Energy Dispersive XRay Fluorescence – EDXRF), phase composition (X-ray diffraction – XRD) and surface state in terms of roughness and gloss. Results: Aging protocols did not affect the tested chemical composition stability of specimens and a high share of stabilizing yttrium-oxide (≥10% of total content), which correlates with the absence of monoclinic phase. A decrease in gloss on all specimens is statistically significant. Chemical degradation substantially increased the surface roughness of tested specimens. Conclusions: Translucent monolithic zirconia demonstrated a stable chemical composition and resistance to tetragonal-to-monoclinic transformation. Surface gloss was significantly reduced, especially in polished specimens. Contrary to glazed specimens, the tested polished specimens manifested an increase in surface roughness. Glazing the surface of translucent monolithic zirconia produces better esthetic, tribological and hygienic effects than polishing.

Labels as a graphic product are important for information in declarations, especially for languages of smaller nations. Labels are increasingly required together with their ever more complicated technical performance, one of them being the desire to adapt the text to blind or partially sighted users. We therefore tested the possibility of using a declaration text in black with overprinted Braille cells with no or minor influence on legibility. The research was performed by analyzing the influence of printed cells on the achromatic halftone reproduction. The prints of the text and the overprinted Braille cells were made with a UV LED inkjet printer. Two different typefaces in two different sizes suitable for labelling were tested. The color properties were determined colorimetrically and the differences in the typographic tonal density of typefaces were measured with an image analysis. The legibility research was performed with the help of observers who read the plain printed text and the printed text in combination with overprinted Braille cells made with varnish. The results showed that an appropriate typeface and type size can reduce the influence of overprinted Braille on text legibility.

One of the problems in the offset printing technique is the picking of uncoated paper, which occurs due to the activity of pressure cylinder and sticky offset inks. To reduce offset ink stickiness, it is possible to add cheaper ink filler that will indirectly reduce the concentration of pigment. However, there is also a reduction in the colour tones and quality of reproduction. In this experiment we used: standard cyan offset ink (Sun Lit Express ink which consists of phthalocyanine based pigment) and high-quality gloss coated cardboard (250 g/m2 Euroart plus gloss). This paper aims to show how the CTP screening type (AM/FM mode) and the CTP line screening (80, 100, 120 line/cm and 10 μm, 20 μm 25 μm diameter of print elements) manifest on the reproduction quality of a standard gradation wedge. This research will create the possibility of correlating the factors of user reduction of pigment concentration and reproduction quality of cyan colour separation. By using the AM screenings and adding different concentrations of ink filler, more stable cyan prints are achieved.

Nowadays, Inkjet technology has become one of the most widespread printing technologies in car industry (car wrapping = printing and wrapping the whole vehicle or a part of a vehicle in printed foil). Printed wrap foils are, after the wrapping process, exposed to the same conditions as a lacquered vehicle: intensive sunlight, high and low temperatures, rainfall, snow, ice, particles or bugs that the vehicle encounters while driving, etc. In this paper we tested different types of wrapping foils (Orajet, 3M Scotchcal and 3M Controltac) and solvent inkjet inks to investigate the influence of different types of wrap foils on the real reproduction of UV ink jet coloured imprints, as well as their stability fluctuations during ageing. The inkjet prints age faster under the influence of UV light (Xenon lamp in SolarBox) in a period of 240 hours. The results show that the 3M Scotchcal foil has the best CMYK stability.

An increasing requisite regarding the reproduction quality of electrophotographic printing machines demands improvement of new electrophotographic toner formulation, especially used pigments. The subject of this paper is a comparison of prints realised by depositing high chroma (HC) and standard emulsion aggregation (EA) toner on gloss fine art paper. HC toner has a different composition of the cyan and magenta tones compared with the corresponding standard EA toner tones and therefore behaves differently under real conditions. The patches used for this experiment were cyan and magenta tone prints with tone values (TVs) of 0, 20, 60 and 100%. Ultraviolet (UV) degradation was measured over time intervals of 0, 6, 12, 24, 48, 96, 144 and 240 h for all patches. Results (laboratory values) were calculated using colorimetric difference. Values were plotted as a function of time in tonal degradation graphs. A model was created using non‐ linear regression‐based modelling. The experiment demonstrates that magenta patches are more susceptible to degradation in comparison with cyan patches. With the increase in tonal value, it is noticeable that the colorimetric difference is higher. Colorimetric differences calculated using HC magenta toner and standard EA cyan toner (100% TV) were higher than ΔE = 5, starting to appear after 6 h of exposure to UV radiance. After 12 h of exposure, colorimetric differences of standard magenta tones that were greater than ΔE = 5 alsonstarted to appear. Cyan patches (100% TV) printed with HC toner were more stable than the other patches, and after 240 h of exposure had not crossed the boundary of ΔE = 5.

The directions of the ecological sustainability in printing reproduction are in the area of the application of the renewable and recycled raw materials, in the decrease of the energy consumption, the usage of the energy from the renewable sources and in the production without waste. This article presents the research results of voltage changes of the intermediate cylinder in indirect electrophotography with liquid toner on dirt count and area on handsheet made from fibers after prints pulping and flotation, brightness and effective residual ink concentration. Since on the indirect transfer of ElectroInk except the voltage of the intermediate cylinder also impacts temperature, its influence on the dirt count and area is showed. Uncoated and both side coated substrates were used for printing. The results show that changes in voltage of the intermediate cylinder in the printing affects the characteristics of pulped and floated fibers and dirt count and area on handsheets. Dominant factor of studied process is surface treatment of the printing substrate. Maximum efficiency of deinking flotation (87.7%) was observed on non coated paper print, at the voltage of the intermediate cylinder of 700V. The efficiency of deinking flotation on both sides coated paper prints in dependence on the voltage of the intermediate cylinder in most cases is below 10%. The results show that an increase in temperature of the intermediate cylinder increases dirt count and area on handsheetst after pulping prints under experimental conditions. Increased efficiency of flotation was found for print obtained at a lower temperature of the intermediate cylinder.

Everyone has the right to freely participate in the cultural life of the community (United Nations, 2012). In Europe and around the globe, many efforts have been made in order to include people with visual impairments and blindness into the cultural life (Braille Authority, 2012; Brvar, 2010; European Blind Union, 2011; Kennedy, 2003; Kurze, 1996; Salzhauer Axel & Sobol Levent, 2003; Wright, 2009). The objects and artifacts exhibited in museums for people with visual impairments are available either by direct touch of the original or its 3-D reproduction. Paintings, on the other hand, require a different approach--usually a tactile adaptation is created. This paper describes the process used to create a tactile adaptation of the painting Portrait of Empress Elisabeth of Habsburg, which hangs in the Celje Regional Museum in Slovenia as a part of the Cultural and Art Historical Collection. It was painted between 1873 and 1875 by the Austrian artist Georg Martin Ignaz Raab. The Empress Elisabeth, also known as Sissi (1837-1898), was famous especially in the Habsburg monarchy for her extreme beauty and unconventional style of life. Her life inspired many movies that ensured her legacy for generations to come. There are many techniques used in tactile adaptation. Two are used very often, namely the microcapsule technique (Braille Authority, 2012) and the thermovacuum technique (Rener, 1992). To create a tactile adaptation in this study, a new technique with an inkjet printer, the Roland UV LEC-330, was tested (Roland, 2012). The printer uses a special varnish that can be cured by ultraviolet (UV) light to generate raised relief surfaces printed layer by layer. This cannot be used for numerous copies, though, as the printing procedure is very time consuming. The printer adjustment and mistake correction are simple because the technique is digital. Apart from these technical aspects, we also explored ways of conveying the content of the actual image as best we could (Salzhauer Axel & Sobol Levent, 2003). The painting was carefully transformed into a tactile adaptation with the help of a museum expert; thus, during the adaptation, all historically important data were preserved. The process unfolded in three stages that are described below. In each stage, in addition to the technical use of the printer, subjects who are blind or visually impaired were interviewed to tell us whether the information at that point in the adaptation was easily perceived tactilely or not. Their comments were taken into consideration in the following stage. The final, third adaptation now hangs alongside the painting in the museum, where it is available for museumgoers who are blind or visually impaired. METHODS Subjects The subjects who participated in this study were found with the help of the Slovenian Association of People with Visual Impairments and Blindness and the Institute for Youth with Visual Impairments and Blindness of Slovenia. Our aim was to exhibit the tactile adaptation in a museum. Our main criterion was, therefore, that subjects be interested in art and the exploration of art. The average age was 35 years. All subjects agreed that tactile adaptation is useful and a likeable medium that helps improve their understanding of the visual world. Not all subjects were involved in all three stages of the adaptation. In Table 1, their involvement and some demographical data are presented. Three stages of adaptation The painting's dimensions are 79 x 63.3 centimeters (roughly 31 x 25 inches) (see Figure 1). The tactile adaptations, due to size restrictions connected to the sense of touch, were smaller--only 36 x 29 centimeters (approximately 14 x 11 inches) in size (Brvar, 2010). The three tactile adaptations were printed in a similar way, with only minor differences. Table 2 shows printer settings and printing conditions. The appropriate museum expert was consulted throughout the procedure; however, the historically relevant features were determined beforehand. …

The results from an investigation of the colour characteristic and changes in the size and shape of yellow screen elements of LEP (Liquid Electro-photography Printing) prints exposed to moist-heat ageing are presented. Three sample series are analysed: prints on the non-aged paper, accelerated aged prints and prints on accelerated aged paper. The results showed that prints on the aged recycled paper and on aged fine art paper show greater colour change than aged prints on non-aged paper. The tonal values were influenced by such printing substrates on the yellow reproduction. A decrease in colour differences of prints appears on the aged offset paper used as printing substrate by increasing the screen value in area of 10%-20%. Moist-heat aged prints on offset paper influences the decrease of yellow screen elements, which is not the case for the prints made on recycled paper and those made on fine art paper. Printing on the aged paper results especially in a 30% increased reproduction of the screen elements in darker tones. On all the three paper kinds greater deviations were found along the horizontal length of the screen element in comparison to the vertical diameter length.

The machine printing and rapid cultural development in Europe begins with the discovery of metal lettering at the end of the 15th century. This printing technique has been named the letterpress printing and is one of the greatest inventions of mankind. The development of printing was one of the main indicators of the development of individual countries. We believe that today in the world and in Europe the Croatian development of that age is significantly neglected. This paper presents European development and development in Croatia. This paper will contribute to a more accurate evaluation of Croatian printing and cultural level of that time by displaying Croatian achievements of that era, the printing staff, printed works and printing houses, throughout European and Croatian development of printing.

The aim of this work was to determine the dependence of the colour fading of offset prints on the ageing process, relative to prints overprinted with water-based dispersion varnish and UV-cured varnish. Natural ageing (outdoor conditions and the exposure to sunlight filtered by glass windows) and accelerated ageing (moisl heat and light xenon arc lamp) treatments were carried out. In order lo determine colour fading, colour difference, 2D gamut values and characteristic cross sections L20, L50 and L80, as well as 3D gamut values were used. The yellow colour showed the largest colour difference when offset prints were exposed to accelerated ageing by means of exposure to xenon light. Magenta followed yellow. No significant stability was achieved by varnishing the yellow print with water-based dispersion varnish and UV-cured varnish. This was also the case with magenta. An increase of the gamut occurred after one week's exposure of prints coated with water-based dispersion varnish to moist heat ageing. In contrast, on exposure of prints coated with UV-cured varnish, a decrease of gamut appeared. On further exposure of prints covered with either kind of varnish a decrease of gamut was evident. Indoor exposure of varnished prints to sunlight through a glass window had a minor influence on the gamut volume change in comparison with the exposure of prints to outdoor conditions.

Trajnost crno-bijelih Inkjet otisaka izrazito je važna. Na žalost izlaganjem otisaka vlazi ima za posljedicu gubitak otisnutog sadržaja. Zbog nepostojanja univerzalne Inkjet boje potrebno je ispitati 3 tipične Inkjet boje: Inkjet otisci otisnuti crnom UV sušećom bojom, otisci otisnuti crnim dye Inkjet bojilima i otisci otisnuti crnim pigmentiranim Inkjet bojom. Za ovo ispitivanje napravljen je poseban uređaj koji će provesti simulaciju vlaženja (efekat oborinskih padalina) principom kap na kap. Eksperimentom su uključena 4 vremenska perioda vlaženja (0h, 1h, 6h i 24h). Za detekciju promjena akromatskih tonova primjenjena je kolorimetrijska metoda na temelju koje su izračunate kolorne devijacie CIE LAB ΔE00., The sustainability of monochrome Inkjet prints is extremely important. Unfortunately, exposure of the prints to moisture results in loss of printed content. Since there is no universal Inkjet color, it is necessary to examine the following 3 typical inkjet colors: Inkjet prints printed in black UV-drying color, prints printed with black dye Inkjet colorants and prints printed with black pigmented inkjet colourant. To do this test a special device was manufactured to simulate wetting principle of drop in drop (rainfall effect). The experiment included 4 periods of wetting (0h, 1h, 6h and 24h). To detect changes of achromatic tones the colorimetric method based on calculation colour deviation was applied (CIE LAB ΔE00).

High surface texture of textile materials appears rougher and more porous than other printing substrates which can cause excessive ink penetration. Also, high temperature thermal loads affect the characteristics of printed ink and cause structural changes of the textile substrate material as well. The aim of this paper is to determine the influence of thermal load on the print quality of cotton based fabrics with different knitting types via surface macro nonuniformity and line quality determination of the printed samples. The research results indicated that the thermal load had a negative influence on the line quality parameter and a positive effect on the macro non-uniformity parameter.

Svrha: Analizirati parametar translucencije (TP vrijednosti) staklokeramika izrađenih različitim tehnološkim postupcima te ispitati kako na TP vrijednosti utječu korozivna sredstva. Materijali i metode: Izrađena su po tri uzorka IPS e.max keramike (Ivoclar Vivadent, Schaan, Lihtenštajn) u trima bojama (A2, C2 i B3) s trima različitim tehnologijama izrade (slojevanje – e.max Ceram Dentin; toplo-tlačna tehnika – e.max Press; strojno – e.max CAD). Uzorci su bili u obliku pločica dimenzija 10 mm x 12 mm x 0,8 mm. Spektrofotometrom (X-Rite DTP 20 Pulse, Neu Isenburg, Njemačka) izmjerene su CIE L*a*b* vrijednosti za izračun parametra tanslucencije (TP vrijednost) prije i poslije izlaganja 4-postotnoj octenoj kiselini na 80 °C tijekom 16 sati (ISO 6872). Statistički podatci obrađeni su programom IBM SPSS 22. Rezultati: Značajno najmanje TP vrijednosti imao je IPS e.max Ceram Dentin, a najveće IPS e.max Press u svim bojama, prije i poslije izlaganja kiselini (p, The purpose of the study was to analyse translucency parameter (TP values) of glass-ceramics fabricated by different techniques and investigate the effect of the corrosive medium on TP values. Materials and methods: Three specimens of each type of IPS e.max ceramics (Ivoclar Vivadent, Schaan, Liechtenstein) were made in three colours (A2, C2 and B3) by three fabrication techniques (layering – e.max Ceram Dentin; heat-pressing – e.max Press; CAD/CAM – e.max CAD). Specimens were made in the form of plates (10 mm x 12 mm x 0.8 mm). CIE L*a*b* values were measured by a spectrophotometer (X-Rite DTP 20 Pulse, Neu Isenburg, Germany) before and after exposure to 4% acetic acid at 80 °C for 16 hours (ISO 6872) to calculate translucency parameter (TP values). Statistical data were analysed using the IBM SPSS 22 software. Results: IPS e.max Ceram Dentin had significantly the lowest TP values, and IPS e.max Press the highest TP values of all colours (A2, C2, B3), both prior and after exposure to acid (p

Printed fabric is widely used, and it is exposed to various influences. One unavoidable impact is heat treatment during subsequent maintenance – ironing. Hence, many printed textile materials are exposed to different temperatures. Textile can be printed with conventional (screen) and digital (Inkjet) print technologies. In this paper, we analyzed screen printed textile and its sustainability after heat treatment. Heat can not only change the reproduced colour, but also affects the print uniformity (print mottle). The goal of this paper was to find what could be controlled and changed in order to get long-lasting printed textile. We used one natural textile material – cotton that was printed with screen print technology. Constant parameter during the experiment was a time of heat treatment. Ironing temperature and screen mesh count were varied. Results showed that samples printed with smaller screen mesh count maintain print uniformity after heat treatment.

This article aims to define attributes of image quality that affect the quality of textured UV varnish applied as a pattern effect over offset prints. The most common UV varnishing problems that might influence attributes of print quality are reticulation of the varnish, poor adhesion, spreading of the varnish and shade changes. These problems mostly arise from inability to control the coating, especially if applied on differently generated print surfaces. Benefits of UV coatings in terms of image quality improvements might be greater opacity, color stability, deeper and more vibrant colors, sharper graphics, higher gloss and uniform surface to give labels a more vibrant look. Image quality variation assessment often needs to be carried out since an improvement made to one attribute can result in a deficiency to another attribute or attributes. In order to determine correlations between these attributes, a combination of objective and subjective image quality assessments has been applied.

In accordance with environmental sustainability and in order to optimize the recycling process of prints from indirect electrophotography with liquid toner the results of investigating the effects of changes in printing conditions on the characteristics of recycled fibres is presented. Changing of printing machine conditions, respecting of voltage variations, comprises of the reverse rollers and intermediate cylinder. Based on the results it can be concluded that the change in the voltage of the reverse rollers more affect the recycling efficiency with respect to the voltage change of the intermediate cylinder. Brightness gain is higher when the print for recycling is made on uncoated paper compared to coated, and dependent on the voltage changes. Effective residual ink concentration decreases far more on handsheets obtained from recycled samples on uncoated paper in relation to both sides coated paper. Increasing the positive voltage of intermediate cylinder and increasing the negative charge of reverse rollers increases the 3 D gamut CIE L*a*b* color cubic units. Guidelines for the size of the voltage in order to obtain optimal print reproduction are provided. The further research will include the development in area of clean technologies, advanced materials, closed loop systems; therefore the significant terms in the area of environmental sustainability.

U svrhu postizanja boljih svojstava tiskovne je podloge moguće oplemenjivati na različite načine. U ovom radu analizira se mogućnost oplemenjivanja s različitom površinskom pokrivenošću lakova koji se suše UV zračenjem, pri čemu su korištena tri karakteristična papira (papir za umjetnički tisak gloss, offsetni papir i kalandriran papir). Primijenjene metode su bazirane na mjerenju optičkih svojstava lakom impregnirane površine (obojenje, sjaj i glatkoća), kao i na određivanju fizikalnog svojstva upojnosti. Dvojne osobine papirnih podloga dobivaju se nanosom UV laka koji suši LED svjetlošću. Rezultati istraživanja pokazuju da se kod gloss premazanog papira upojnost smanjuje nanosom UV laka, dok se kod nepremazanih papira (offsetni, kalandrirani) upojnost povećava. Nanos laka s manjom površinskom pokrivenošću (33 % UV laka) nije relevantntna za upojnost i optička svojstva naravnih papira. Značajne promjene u hrapavosti i optičkim svojstava postižu se 66 % nanosom, što je posebice vidljivo kod papira za umjetnički tisak., In order to achieve better properties of the printing substrates their improving is possible in various ways. In this article the possibility of the substrate improving is analyzed with different surface coverage of varnishes cured by UV radiation, where three characteristic kinds of paper were used (fine art glossy paper, offset paper and calendered paper). The applied methods are based on measuring the optical properties with the varnish impregnated surface (colouring, gloss, smoothness), as well as determining the physical property of absorbency. Double properties of the printing substrates are obtained by the layer of UV varnish which is cured by LED light. The investigation results show that the absorbency decreases on gloss coated paper by the application of UV varnish coating, while it increases on uncoated paper (offset and calendered paper). The varnish coating with smaller coverage (33 % UV varnish) is not relevant for the absorbency and for optical properties of the natural paper. Important changes in roughness and optical properties are achieved with 66 % coating which is especially visible on fine art paper.

In this paper, the influence of resolution on the color quality reproduction in digital offset printing were investigated. In our experiment special test charts were printed with different resolutions and compared. The results show that high resolution improve image contrast but not the color reproduction.

Printing material and prints undergo changes during ageing which can be recognized in deterioration in the physical, chemical and optical properties. The aim of this work is to determine the optical changes of the prints caused by ageing of the printing material and of the prints obtained by the application of the indirect electrophotography. The change of the screen elements in lighter halftone areas, which was obtained by the usage of the microscopic image analysis, has been discussed in the article. For the preparation of samples the following papers were used: fine art paper, recycled paper and offset paper as well as black Electroink. Three sample series were observed: prints on nonaged paper and ElectroInk, prints on aged paper and ElectroInk and prints on aged paper and nonaged ElectroInk. The investigation results show that by ageing of the uncoated printing substrates the decrease of the dots on prints can be expected, while the printing on the aged paper results in the increased reproduction of the halftone dots. The obtained results are the contribution to the explanation of the influence of the accelerated ageing process of papers which are used for printing and the aged prints on the halftone dot changes. Except the mentioned determined scientific contribution the results are applicable in the area of the printing product quality as well as in the forensic science.