Title: Aesthetic and Physical Properties of Fused Recycled Bottle Glass
Below is the abstract of the thesis and a few selected images.
This thesis describes the process and results of an investigation into the physical and aesthetic properties of fused recycled bottle glass. Having established that waste bottle glass was being used in bulk in a number of construction-based applications, it was realised that there had been no systematic studies of the properties of the fused material, knowledge of which would allow the applications base to be broadened into other areas such as glass art and industrial design. The underlying rationale for doing the study was the potential environmental benefit of finding alternative uses for a waste material and the belief that the material itself could have unique aesthetic properties.
To be confident in the use of the material, a detailed investigation of the compatibility of fused bottle glass, obtained and mixed from different sources, was undertaken. Using a practice-based approach combined with scientific experimentation, it was found that compatible material can be produced by low temperature fusion. However, it is always necessary to sample and test for internal residual stress. High temperature fusion, so-called ‘hot glass’, always produces compatible material, but has the disadvantage of needing high energy input, and so is not the focus. The impact of low temperature fusion on physical strength as a function of a range of variables was studied. In brief, the results showed that smaller grain size produced stronger material, the strength was not affected by frit addition and the top fusion temperature increased the strength of large grain sized material. Mechanical measurements suggested that it is possible to define a lower limit to the bending strength of the material by selecting experimentally a maximum average internal stress for it.
The colour and texture produced by low temperature fusion were investigated systematically. Using Itten’s theory, a full colour spectrum was produced and reproduced, with lead containing frit. Colour reproduction was also successfully achieved with lead-free frit. Texture was investigated as a function of grain size and fusion temperature. The effect of controlled devitrification on texture was investigated in detail. An interesting outcome of this work was that it is possible to produce three dimensional devitrified objects by pre-slumping low temperature fused material and completing the devitrification in a sand cast mould. Strength tests confirmed that devitrified material is as strong, if not stronger, than conventional ceramics.
To confirm that it is possible to reproduce the material’s properties in an externally specified application, a case study was undertaken in a live project aimed at creating sustainable homes. Kitchen and bathroom tiles were chosen as the applications by the architect leading the commercial project. The tiles satisfied successfully the specifications, which included additional design factors that had not been previously investigated. Non-parametric significance testing of the responses to a questionnaire by three groups of representative prospective purchasers with subject specific knowledge such as design, environmental/sustainable awareness and business/management, confirmed the acceptability of recycled bottle glass for commercial applications.