An investigation has been undertaken to examine the role of the printing plate on tone gain in flexographic printing. Experimental techniques have been combined with finite element models of individual dots to quantify plate deformation as it passes through the printing nip. Dot profiles for three line rulings and two plate thicknesses have been quantified, which showed that dot area on the plate is generally less than the nominal coverage. Dot depth decreased as coverage and line ruling increased, indicating that the line ruling affects the shoulder angle of the dot. Finite element techniques revealed two mechanisms of plate deformation, which were the expansion of the dot surface and barrelling of the dot shoulder. Engagement had the greatest effect on plate gain, with line ruling being the second most important parameter. Coverage had no individual effect on plate gain, although it interacted with line ruling, dot depth and engagement. Results from the experimental investigation showed that total tone gain was significantly higher than results from the numerical investigation, due to ink spreading on the substrate: For high engagements, the difference in tone gain was small, as there was only a finite volume of ink present, restricting its ability to spread. Comparison of experimental and numerical results showed that plate deformation accounted for the majority of total gain for low coverages due to the low volume of ink present for the relatively large dot perimeter. For mid-tone coverages, the proportion of total gain due to plate deformation was approximately one fifth. This increased slightly for coverages approaching the solid as the available perimeter decreased, reducing the ability of the ink to spread .. This investigation has improved fundamental understanding of the role of the plate in flexographic printing. Use of numerical models has enabled exploration of parameters, which cannot be investigated experimentally .

Investigations have been conducted into the transfer of ink from the plate to the substrate in flexographic printing. Four experimental trials have been conducted at full press scale in order to investigate process parameters including substrate type and the effect of over printing previously printed ink. In order that the shape of printed dots could be analysed methods for the determination of plate dot circularity and printed dot circularity were developed. Accurate measurement of the printing plates used in the experimental investigations has revealed significant differences in nominally identical patches within the same plate. Dot size and geometry was found to be permanently altered through the application of pressure in the plate/anilox nip. The volume of ink supplied to the plate is found to have the largest effect on ink transfer to the substrate. Increases in anilox volume and engagement between plate and substrate are found to increase ink spreading. Decreasing viscosity reduces ink transfer to the plate from the anilox which in tum results in lower ink spreading for individual dots. Joined dots however show an increase in ink spreading due to increased entrapment of ink at the nip entrance. The shape of printed dots is found to be affected by the volume of ink transfer and by engagement. Larger dot volumes increase dot circularity and larger engagements reduce dot circularity. The effect of under printed ink on ink transfer of subsequently printed ink is dependent on the coverage of under printed ink and the substrate being printed. For non porous substrate the under printed ink acts as a barrier to ink spreading. On porous substrate the density of samples is increased due to the under print filling surface pores increasing ink spreading for subsequently printed ink. The effect of under print is visible for all substrates and over print coverage's.

This thesis is concerned with the Mathematical Modelling of thermal and laser printers which are often used to provide high quality prints of electronically stored images. These two systems have a similar geometrical structure in which a thin dye-layer is sandwiched between two copolymer sheets. The dye layer is heated and dye diffuses into the receiver sheet producing a small dye-dot. The picture is made up of a large number of such dots. The basic aim is to determine the amount of dye which eventually diffused into the receiver sheet when the heating is turned off and the system has cooled down. The amount of dye which diffuses into the receiver sheet depends on the temperature field because the diffusion coefficient is a sensitive function of temperature. However the structure of the thermal fields in the two systems is very different. In the laser system radiation is absorbed in the dye-layer alone giving a local heating effect. In the thermal printer system the head is heated by an electric current and heat is conducted into the dye-layer. We found that sharp concentration fronts can occur in the laser system, but these are absent in the thermal printer system. We have also made a preliminary study of an optimization problem for a thermal printer head. To study these problems we have used a combination of analytical and numerical methods.

This thesis investigates the collaborative production of fine art digital prints for artists,a process which is used by many contemporary practitioners including Richard Hamilton and Damien Hirst. Digital print as a fine art process has emerged over the last twenty years, and as yet, there is no in depth evidence on the collaborative endeavour and production process which is central to the digital Master Printer’s role. The investigation first establishes the historical context and significance of the Master and Printer in traditional printmaking, and the more recent development of the digital print studio and the digital print pioneers of the 1990s. A series of seven artists’ case studies in the context of the collaborative digital print studio are then offered to demonstrate the working process. The analysis of these proposes a best practice model for Master Printers working with contemporary artists to produce high quality, fine art, wide format inkjet digital prints. The study also compares production methods at the cutting-edge digital facility of the Rijksakademie in The Netherlands, to assess the validity of the practices proposed through a facility closest to the study’s research base at the CFPR’s digital studio. The comparative study also explored the expanding digital production process and the role of the Master Printer. Evolving production processes are also considered in this study as a response to the advancement of digital print technology alongside a practical exploration of what actually constitutes a digital print in this rapidly expanding field of fine art printmaking. This study aims to reveal the inner workings of the digital collaborative process between the artist and Master Printer, and appraise the digital Master Printer’s role. It offers a set of best practice methods for the digital Master Printer developed from this research. The study also considers how the digital print, and the digital print studio may evolve in line with current and future developments in new technologies.

No description available.

No description available.

No description available.

This research explores whether patterns of typographic differentiation influence readers’ impressions of documents. It develops a systematic approach to typographic investigation that considers relationships between different kinds of typographic attributes, rather than testing the influence of isolated variables. An exploratory study using multiple sort tasks and semantic differential scales identifies that readers form a variety of impressions in relation to how typographic elements are differentiated in document design. Building on the findings of the exploratory study and analysis of a sample of magazines, the research describes three patterns of typographic differentiation: high, moderate, and low. Each pattern comprises clusters of typographic attributes and organisational principles that are articulated in relation to a specified level of typographic differentiation (amplified, medium, or subtle). The patterns are applied to two sets of controlled test material. Using this purposely-designed material, the influence of patterns of typographic differentiation on readers’ impressions of documents is explored in a repertory grid analysis and a paired comparison procedure. The results of these studies indicate that patterns of typographic differentiation consistently shape readers’ impressions of documents, influencing judgments of credibility, document address, and intended readership; and suggesting particular kinds of engagement and genre associations. For example, high differentiation documents are likely to be considered casual, sensationalist, and young; moderate differentiation documents are most likely to be seen as formal and serious; and low differentiation examples are considered calm. Typographic meaning is shown to be created through complex, yet systematic, interrelationships rather than reduced to a linear model of increasing or decreasing variation. The research provides a way of describing typographic articulation that has application across a variety of disciplines and design practice. In particular, it illuminates the ways in which typographic presentation is meaningful to readers, providing knowledge that document producers can use to communicate more effectively.

The release of volatile organic compounds to the atmosphere is harmful to human health and the environment. The printing industry is one of the highest contributors to VOC emissions in the UK. According to the Solvent Emissions Directive (1999), only 30 % (by weight) or less of solvents used in the printing industry can be released into the atmosphere as emissions; this is proving to be a challenge to the industry. Thus, the aim of this project is to develop and test a complete demonstration scale capture and regeneration system capable of reusing both, the adsorbent and the adsorbed VOC (in this case IPA). A prototype adsorber was built and tested at a lithographic printing company for the purpose of capturing the isopropanol (IPA) emissions, under industrial conditions. The prototype itself consisted of an extractor pipe and an adsorbent cartridge placed inside a vacuum cleaner. Adsorption was carried out by drawing in air from the printing machines where vapour emitted from the dampening solution (which comprised of about 10% by vol IPA and 90% by vol water) was concentrated. Three trials of varying inlet concentrations with an adsorbent Dowex Optipore V503 (Dow) and a one trial with activated carbon (AC), was carried out at the printing facility. The time taken until the start of breakthrough was approximately 86 minutes and 250 minutes (of printing time) for Dow and AC respectively. Results showed that, until the start of breakthrough, all of the IPA entering the bed had been captured by both adsorbents. Of the material captured on the adsorbent, the percentage that was IPA for Dow was 66 wt% to 80 wt% and the IPA percentage that was captured on AC was 54 wt%. The rest of the captured material on the adsorbents was found to be water. A higher IPA loading, however, was evident for AC as compared to Dow. Results on microwave (MW) regenerating the two adsorbents showed that maximum regeneration of 88% for Dow and 97% for AC occurred after 12 and 13.5 minutes of microwave irradiation respectively. Tiny flashes of light across and within the whole AC bed were evident frequently during the initial stages of MW regeneration. Thus, in terms of safety, the existence of tiny sparks during AC regeneration indicates that Dow is the safer of the two adsorbents. Fractional regeneration of Dow showed that maximum IPA content was found in the regenerate collected between the 6th and 9th minute while the lowest IPA content was found between 0 and 3 minutes. For AC, the percentage of IPA in the regenerate was also found to increase with irradiation time. An attempt was made to model the process. The first step was to obtain the pure adsorption isotherms at 298 K using an Intelligent Gravimetric Analyser (IGA). For the AC and Dow adsorbents, the Toth and the CIMF model fitted extremely well to the pure IPA and water isotherms respectively. The mixture isotherms were described by the virial equation. The results from the mixture experiments involving Dow showed ideal adsorption of the mixture; AC showed highly non-ideal behaviour. A mathematical model (compiled on Matlab), which incorporated the co-adsorption isotherms, was used to predict breakthrough times during fixed-bed adsorption. This model was able to predict breakthrough data for Dow fairly accurately. An economic analysis was conducted which shows that AC is the cheaper of the two adsorbents to use, subject to safety considerations. Overall, a system that captures and regenerates the IPA from the print works had been successfully developed and tested. Microwave regeneration was found to be favourable for both adsorbents since, no loss in adsorbent capacity was found after exposure to microwave radiation. On comparing the two adsorbents, Dow was found to capture a higher percentage of IPA than water as compared to AC. However, with regards to economic viability, AC was found to be the more economic adsorbent.

No description available.