Fountain Solution Research Articles

Effect of Paper Surface Properties on Coated Paper Wettability with Different Fountain Solutions

Wetting of coated papers by isopropyl alcohol (IPA)-based fountain solutions or surfactant solutions was studied in this paper. Additionally, the effect of paper surface properties on wetting was analyzed. To that end, six fountain solutions were prepared. Three solutions had increasing amounts of IPA, and three were made from surfactant-based dampening agents. Eight commercial coated papers were selected and characterized in terms of roughness and surface free energy. Paper resistance to wetting by fountain solutions was evaluated by measuring the static and dynamic contact angles. Static contact angles between the paper surface and the IPA-based fountain solutions decreased as the alcohol concentration increased, whereas the wettability with surfactant-based fountain solutions was highly dependent on their surface tensions. Paper surface free energy strongly affects the static contact angle and only moderately affects the dynamic contact angle.

The influence of paper surface energy on multicolor offset print mottling

An evaluation of a series of commercial uncoated, semimatte, and glossy coated woodfree papers for the multicolor sheet-fed offset press is presented. This study is aimed at better understanding of mutual influences of surface free energy, paper surface roughness, and fountain solution on print mottling occurring in full-scale printing conditions. Each paper has unique structure in terms of surface roughness, porosity, and surface energy that are the result of manufacturing technology. At the point of contact of liquid with paper, the surface dynamic process of liquid absorption by paper occurs, involving phenomena such as wetting, penetration, diffusion, and swelling. Mottling of colored surface printed by cyan, magenta, yellow, and black inks copied the surface roughness of coated paper. Mottling in the second, third, and fourth printing units showed deviation from mottling in the first printing unit, depending on surface free energy of paper and on the frequency of paper-surface wetting by fountain solution before and after printing.

Investigation to Determine the Amount of Fountain Solution Applied to Paper in Offset Printing and the Effect of the Fountain Solution Properties on the Print Quality

Investigation to Determine the Amount of Fountain Solution Applied to Paper in Offset Printing and the Effect of the Fountain Solution Properties on the Print Quality

Transport of Immiscible Vapor Pressure Contrasting Liquids in Multiple Nip Impressions: Application to Heatset Offset Printing of Paper

A multistation heatset offset printing press was studied here to exemplify the transport of immiscible liquids into a porous substrate under dynamic rolling nip conditions. In offset printing, oil-based ink and a water-based fountain solution are used to define the image and nonimage areas according to the respective surface energy of the printing plate. The fountain solution and ink inevitably form an emulsion after the press has run sufficiently to reach equilibrium. It is this emulsion that is transported via a rubber blanket to the paper and forms the printed image. The emulsification degree depends on the ink properties and the printing process at the equilibrium ink–fountain solution balance, which, in turn, supports stable continuous running of the press in order to achieve a good print quality. Focus is given to the transfer of fountain solution to both nonimage areas of paper as well as to the inked areas carried in the emulsion. In order to monitor the amount transferred, each of two tracing ele...

Fountain Solution Trends in Recent Years

Fountain Solution Trends in Recent Years

The influence of pH/conductivity of fountain solution on dot circularity, line and textraggedness

The influence of pH and conductivity of fountain solutions on the quality of dot, line and text raggedness was investigated. Physico-chemical parameters of fountain solutions were analyzed by standard methods. Image quality assessment (IQA) was carried out using the ISO methodology and ImageJ software. There is a great influence of pH and conductivity of fountain solutions on the final quality of magenta prints. Magenta dot circularity on the printed sheets showed the mutual nonlinear dependence, second-order polynomial, followed by equation: y = 0.00514x2 - 0.07524x + 0.78238. Line analysis pointed out the least raggedly edges of 1pt horizontal and vertical lines. Times printed text had the most raggedly edges in comparison with Arial. The results indicated that the dot circularity, line and text raggedness could be useful attributes in the quality control of offset prints

The Study of the Printability on the Phenol Free Heat-Set Web Inks(III) - Effects of the Emulsification of Ink on Print Quality -

The lithographic process depends on a satisfactory ink-in-water emulsion being formed during printing and the speed of wet presses makes the choice of fountain solution vitally important as the ink and fount must react quickly to form a stable emulsion. Ink and water come into contact with each other on the rolls of the press and are forced together in the roll nips. The water is not soluble in the ink since it is slightly fat. Instead, an emulsion is formed, a heterogeneous mass consisting of small water drops mixed into the ink, if the water feed is too great. This emulsification can affect the properties of an off-set ink and negatively affect the printability. So we investigated the effects of the emulsification of phenol free heat-set ink and existing heat-set ink on printed quality, such as amount of ink transfer, printed density, print-through and uniformity. We used Duke emulsification tester for the emulsification of inks, and used IGT printability tester for printed quality. The printed quality were measured by densitometer and were evaluated by the image analysis system. Compared to conventional printing ink, phenol-free ink showed better results of the printability at the emulsification. Keyword : emulsification, phenol-free heat-set ink, printability, Duck emulsification tester, densitometer

Combining simulation and on-line measurements to determine moisture transport dynamics throughout the heatset offset printing process

The aim of the study was to explain the transportation of liquid (fountain solution) during transfer to coated paper in the heatset offset printing process, together with the subsequent drying of the printed paper, by using statistical and experimental methods.A coating dispersion, applied as a single coating onto a fine paper substrate, was formulated using a narrow fine particle size distribution natural ground calcium carbonate pigment and a styrene acrylic binder. The moisture variation in the paper during printing was monitored by using online multipoint sensors based on near-infrared diffuse reflectance spectroscopy. Based on the results, a simulation model was created to determine the transfer of liquid thin films in the printing units, the evaporation in the printing units, followed by liquid absorption and evaporation in the heatset offset drying process. An accurate simulation depends on precise determination of the different process parameters that influence these factors.The absolute liquid/moisture amount transferred to the paper showed an increased trend as the paper passed through the application nips, though the proportion varied due to limited capillary absorption capacity properties of the paper. The background evaporation in the printing nips was evaluated with the simulation model as well as the drying stages in the dryer including surface and bulk condensation followed by rapid evaporation and cooling.

Effective Thermal Conductivity of Liquid-Saturated Coatings and Their Liquid Vaporisation Behaviour

The effective thermal conductivity is an important element in understanding the thermal response to heating of a paper coating, e.g. during drying in heatset web-offset, and thus it not only affects the drying efficiency but also affects print quality detriments like web fluting. This study examines both the effective thermal conductivity of liquid-saturated ground calcium carbonate coating structures as well as the vaporisation behaviour from these structures. The liquids used for saturation were mineral oil and water in order to resemble ink and fountain solution, respectively, both of which are present in the traditional heatset web-offset process. The effective thermal conductivities of liquid-saturated coating structures are discussed in regard to the corresponding unsaturated systems by using a Lumped Parameter Model. It is shown that the liquid saturation has a dominant effect in determining the effective thermal conductivity. Since this effect is not fully captured by the model, other mechanisms like an apparent pigment–pigment connectivity increase by liquid bridging and the role of liquid in changing the contact resistance during the measurement of thermal conductivity are discussed. In addition, the transformation of three-dimensional structures to an equivalent two-dimensional modelling is evaluated. The vaporisation behaviour of mineral oil and water is studied by a thermogravimetric analysis. By following the changes in maximum evaporation temperatures and evaporation rates, the addition of binder is seen to lead to a reduction in the vaporisation rate of both liquids. Since there is little to no interaction between the liquids and the binder, the confinement caused by the geometry change induced by binder addition is identified as the mechanism resulting in elevated vapour pressure within the structure.

Online detection of moisture in heatset printing: Liquid transfer to printed image and non-image areas

Abstract In the present study, near-infrared sensors are used to investigate moisture variations on paper in the heatset web offset printing process. The moisture content was determined from both non-image and image printed areas at multiple locations along the printing line. The amount of water based liquid (fountain solution) transferred to the two studied areas as well as the internal moisture content of the paper was investigated in terms of near-infrared absorbance response. In order to achieve absolute moisture content estimates, the sensors were calibrated for the respective measurement regions. It was found that the moisture content was higher in the areas with printing ink compared to those without. The heatset drying had a stronger moisture drying effect on the non-image areas. The tests were performed in both a laboratory and a full-scale heatset offset printing environment.

Temperature and moisture effects on wetting of calcite surfaces by offset ink constituents

Offset printability is influenced by interactions between ink constituents: linseed oil, mineral oil and water (fountain solution), with the mineral surfaces of paper coatings. To exclude complications of the porous structure effects, the influence of temperature and moisture on wetting by offset ink model liquids were studied on cleaved optical calcite surfaces with and without sodium polyacrylate dispersant. Contact angle measurement was chosen as the method of analysis. The results show that a moderate temperature increase from 25 °C to 60 °C, which might occur in the process, does not affect the wetting of these surfaces by mineral oil. Water and linseed oil are affected by the transport of moisture at the surfaces as an indirect consequence of temperature increase. The linseed oil behavior was found to be sensitive to polarity changes of the surfaces.

The Influences of Printing Conditions and Paper Properties on Wet Picking/Repellence of Offset Paper

The wet picking and wet repellence of offset papers were studied using IGT-gst2 printability tester according to change printing conditions as printing speed and the amount of fountain solutions. It was showed that the phenomena of wet picking and wet repellence occurred in turn on the surface of offset papers with increased printing speed and the amount of fountain solution. In addition, in contrast with fountain solutions, printing speed had greater influence on the phenomena of wet picking and wet repellence of offset papers.

Study on Wet Picking/Wet Repellence at the Grain Direction of Offset Paper

The wet picking and wet repellence of offset papers were studied using IGT-gst2 printability tester according to change printing conditions as printing speed and the amount of fountain solutions. It was showed that the phenomena of wet picking and wet repellence occurred in turn on the surface of offset papers with increased printing speed and the amount of fountain solution. In addition, in contrast with fountain solutions, printing speed had greater influence on the phenomena of wet picking and wet repellence of offset papers.

The Effect of Printing Conditions on Wet Picking and Wet Resistance on the Surface of Offset Paper

The wet picking and wet resistance of offset papers were studied usingIGT-gst2printability tester according to change printing conditions as printing speed and the amount of fountain solutions. It was showed that the phenomena of wet picking and wet resistance occurred in turn on the surface of offset papers with increased printing speed and the amount of fountain solution. In addition, in contrast with fountain solutions, printing speed had greater influence on the phenomena of wet picking and wet resistance of offset papers.

Flint Group North America launches eco-friendly inks and a one-step fountain solution for sheetfed printers

Flint Group North America launches eco-friendly inks and a one-step fountain solution for sheetfed printers

Flint Group North America Launches eco-friendly inks and a one-step fountain solution for sheetfed printers

Flint Group North America Launches eco-friendly inks and a one-step fountain solution for sheetfed printers

Use of confocal laser scanning microscopy and a computer model to understand ink cavitation and filamentation

In the offset printing process, ink film splitting has an important impact on formation of ink filaments. The filament size and its distribution influence the leveling of ink and hence affect ink setting and the print quality. However, ink filaments are difficult to image due to their short lifetime and fine length scale. Due to this difficulty, limited work has been reported on the parameters that influence filament size and methods to characterize it. We imaged ink filament remains and quantified some of their characteristics by changing printing speed, ink amount, and fountain solution type. Printed samples were prepared using a laboratory printability tester with varying ink levels and operating settings. Rhodamine B dye was incorporated into fountain solutions to aid in the detection of the filaments. The prints were then imaged with a confocal laser scanning microscope (CLSM) and images were further analyzed for their surface topography. Modeling of the pressure pulses in the printing nip was included to better understand the mechanism of filament formation and the origin of filament length scale. Printing speed and ink amount changed the size distribution of the observed filament remains. There was no significant difference between fountain solutions with or without isopropyl alcohol on the observed patterns of the filament remains.

Changes in the surface roughness of aluminium oxide (non-printing) areas on offset printing plate depending on number of imprints

A printing and non-printingsurface structure of the offset printing forms are key factors in maintaining the conventional offset printing. The main characteristics of the surface are: physical and chemical structure, surface tension and surface roughness. Surface topography is one of the critical factors which could cause the instability in the quality performance and the durability of the printing forms. During the printing process these characteristics change and directly influence the print. Performed investigations are based on the fact that the changes in physical-chemical properties of the non-printing areas as well as the changes in the surface micro structure of the printing forms directly influence the quality of the reproduction. In this paper, the behaviour of non-printing elements of a thermal CTP plate developed in a fresh developer and used for a print run of 123.000, 177.000 and 300.000 copies on a web offset heat-set printing press has been investigated. Investigation made in a paper showed that high depth of focus SEM (Scanning Electron Microscope) can provide detailed topographical information about the surface, but cannot provide quantitative topographical information. Due to this fact, the printing forms have been also ob-served and analysed before and after the print run by a mechanical stylus profilometer. The investigations reveal the appearance of the physical changes as well as the geometrical ones. As a result of these changes, the influence of a fountain solution on the printing form may also vary, as well as the balance between the ink and the fountain solution during the printing process.

Determination of the Dynamic Surface Tension of a Model Fountain Solution by Measurement of Single Bubble Volume

Determination of the Dynamic Surface Tension of a Model Fountain Solution by Measurement of Single Bubble Volume

Dynamic analysis of temporal moisture profiles in heatset printing studied with near-infrared spectroscopy

Dynamic analysis of the water transfer onto coated paper, and its permeation and absorption into the porous structure were studied online in a full-scale heatset web offset printing environment. The moisture content of the paper was investigated at five different positions during the printing process. Changes in the moisture content of the paper were studied as a function of the web temperature, printing speed and silicone application in the folding unit positioned after the hot air drying oven. Additionally, the influence of fountain solution composition on the pick-up by the paper was investigated. The water content of the fountain solution transferred to the paper from the printing units was observed as changes in near-infrared absorbance. A calibration data set enabled the subsequent quantification of the dynamic moisture content of the paper at the studied locations. An increase in the printing speed reduced the water transfer to the paper and an increase in web temperature resulted in a reduction in the moisture content. An increase in the dosage level of the water–silicone mixture was observed as a re-moistening effect of the paper. Differences in the drying strategy resulted in different moisture profiles depending on the type of fountain solution used. As a conclusion, the near-infrared signal provides an effective way to characterize the moisture dynamics online at different press units.