Thesis (M.S.)--Rochester Institute of Technology, 1993. / Typescript. Includes bibliographical references (leaves 58-62).

Inaug.-Diss.--Halle. / Lebenslauf.

Thesis (M.S.)--University of Wisconsin--Madison, 1946. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.A.)--University of Wisconsin--Madison, 1982. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 47-48).

Thesis (M.Eng.)--University of Louisville, 2006. / Title and description from thesis home page (viewed Jan. 30, 2007). Department of Chemical Engineering. Vita. "August 2006." Includes bibliographical references (p. 52-53).

Thesis (M.S.)--Rochester Institute of Technology, 2007. / Typescript. Includes bibliographical references (leaves 107-109).

Achieving and maintaining the correct ink/water balance is crucial for acceptable print quality; this involves factors affecting the emulsification of water and ink. This process was investigated with two designed model ink varnishes (one being 'hydrophilic' relative to the other 'hydrophobic' varnish) and two commercial varnishes. The Surland test, widely used to characterise ink/water balance, showed differences in water uptake between inks and corresponding varnishes; however it did not distinguish between the 'hydrophilic' and 'hydrophobic' systems. Thus, the rheology of the systems are considered together with implications to the lithographic process. Rheological studies of creep and flow showed that the hydrophilic and hydrophobic systems behaved differently in the presence of water. The rheology of the ink varnish plays a major role in emulsification and the nature of processes at the interface affecting droplet fragmentation, droplet coalescence and time-dependency. Slippage occurred in the hydrophobic systems to a greater extent compared with the hydrophilic systems increasing with water concentrations from 0 to 25% water. Droplet size distributions of the emulsion depend on temperature and agitation speeds. As emulsions approached dynamic equilibria, mean droplet diameters in the hydrophobic varnish at 70°C and 40°C were found to be ca. 2S and 12 I'm respectively; corresponding mean droplet diameten in the hydrophilic varnish were ca. 20 I'm and 5 I'm. Increase of interfacial tension for both varnishes (ca. 6 mNm-l) between 40°C and 70°C, may not be significant to droplet breakdown. A reduction in viscosity i.e. from 100 to 5 Pas in the hydrophobic varnish and from 300 to 5 Pas for the hydrophilic varnish was the determining factor. Droplet size depends on temperature: e.g. temperature increases led to larger droplets. Viscosity ratios of the continuous and disperse phases account for these effects. Investigating the time-dependency of the system showed that allowing 'rest periods' between episodes of mixing altered the rate and nature of emulsification. Thus using a modified varnish, rest periods of 1 and 3 minutes produced mean droplet diameters in the range of 1.5-1.8 um whereas rest period of 5 minutes produced diameters of 2.3-2.4 I'm indicating that thixotropic recovery which occurs up to 3 minutes, restores the rate of droplet breakdown; whereas, after 5 minutes, coalescence is dominant. Extending the 'rest period' allows time for drainage of a film of continuous phase between two colliding droplets. These time-dependent effects varied with different varnish modifications. The effect of IP A on emulsification was also time-dependent. During 3 minutes of stirring at 900 rpm, the number of droplets below 2 I'm was greater in an emulsion containing IP A than in one containing water only; the situation was reversed after 4 minutes of stirring where the number of droplets below 2 um was lower. A decrease in interfacial viscosity at the varnish/water interface is considered; such a decrease may reduce the effective shear stress at the interface and thus the extent of droplet breakdown.

In packaging, spot colours are used to print key information like brand logos and elements for which the colour accuracy is critical. The present study investigates methods to aid the accurate reproduction of these spot colours with the n-colour printing process. Typical n-colour printing systems consist of supplementary inks in addition to the usual CMYK inks. Adding these inks to the traditional CMYK set increases the attainable colour gamut, but the added complexity creates several challenges in generating suitable colour separations for rendering colour images. In this project, the n-colour separation is achieved by the use of additional sectors for intermediate inks. Each sector contains four inks with the achromatic ink (black) common to all sectors. This allows the extension of the principles of the CMYK printing process to these additional sectors. The methods developed in this study can be generalised to any number of inks. The project explores various aspects of the n-colour printing process including the forward characterisation methods, gamut prediction of the n-colour process and the inverse characterisation to calculate the n-colour separation for target spot colours. The scope of the study covers different printing technologies including lithographic offset, flexographic, thermal sublimation and inkjet printing. A new method is proposed to characterise the printing devices. This method, the spot colour overprint (SCOP) model, was evaluated for the n-colour printing process with different printing technologies. In addition, a set of real-world spot colours were converted to n-colour separations and printed with the 7-colour printing process to evaluate against the original spot colours. The results show that the proposed methods can be effectively used to replace the spot coloured inks with the n-colour printing process. This can save significant material, time and costs in the packaging industry.

This research into intaglio printing, its materials and techniques, deals with the three main conservation problems specific to the process. They are: acidity of the paper, buckling and/or tearing along the printed edge of the plate caused by excess pressure during printing, and yellow/brown staining, or halo, around the printed image. Research done in the cause of this study reveals that these problems are not confined to contemporary printmaking practices, as believed by some conservators, but can be traced back to the historic beginnings of the Intaglio Printing. The results of the analyses and tests performed in this investigation indicate that these problems can be partially, if not completely, eliminated by simple and inexpensive improvements to the process of printing. 1 - An alkaline solution, used to dampen the paper prior to printing, will act as a buffer, making the paper resistant to future attack from acids. Importantly, it will also accelerate the drying of the ink, which is essential to the production of a thick solid ink-film. 2 - Excessive pressure during printing destroys the natural resilience of the paper within the printed area and should be kept to a minimum. Plates that have not been bevelled sufficiently can also be very harmful to the paper, cutting and/or tearing paper fibres. These problems are not visually evident after printing, but are ultimately very detrimental to the life of the print. 3 - The traditional method of drying prints, between blotters and under weight, is a major cause of the yellow/brown staining, or halo, formed around the printed image. The vehicle in the ink, a product of linseed oil, normally dries by polymerization and oxidation reaction with oxygen from the atmosphere. Press-drying retards this reaction causing the paper to absorb part of the vehicle. Air-drying accelerates the drying process, producing a much thicker and stronger ink-film and reducing absorption of the vehicle into the paper. Although air-drying will produce buckling, this can be easily remedied after seven days by dampening the print and press-drying.

No description available.