An investigation into the creative use of thin-shell and higher aspect ratio forms within studio glass kiln casting.
Pollock, Anthony (2013) An investigation into the creative use of thin-shell and higher aspect ratio forms within studio glass kiln casting. PhD thesis, University of Sunderland.
This research is based in the field of contemporary glass art. It explores some of the significant limitations of forms that result from methods for simple gravity kiln-casting of glass within today’s studio environment. The research is additionally informed by technologies from disciplines other than glass (industrial metal casting). The aim was to extend the range of possible cast glass art works that can be achieved, encompassing thinner and/or higher aspect ratio forms.
One of the main constraints to form is the need to transform glass from its molten state into homogeneous objects at ambient temperature, without resultant cracks or residual stresses. The baseline for this research attempts to illustrate how forms and shapes have historically tended to align with current process limitations.
The starting point for this practice-led research was to investigate three by-products of the kiln casting process – currently considered undesirable or unnecessary – and investigate their controlled repeatability and potential to create new forms. The by-products were (1) ‘feather edge’ forms resulting from mould leakage, (2) glass ‘shells’ left by inadvertent mould evacuation or bursting, and (3) thin-walled glass forms left in the glass reservoir area of moulds. Practical and analytical baselines were drawn together as a platform to develop new processes that could be used to extend the achievable range of forms. Creative practice was utilised to demonstrate the applicability of new processes, during the making of final art works that related to interpretations of the vessel as a general form.
Multiple processes were investigated by practical experimentation until convergence was reached in terms of repeatability and artistic merit with one chosen technique - that of a soft, thin-walled plaster/molochite mould that is supported in a sand reservoir. Critical to this process was the ability of the thin mould to crack in a controlled manner during cooling of the glass, thus allowing thinner and higher aspect ratio glass forms to be cast successfully without subsequent glass cracking. A subset of this process was the usage of low density urethane foam to form ‘positive’ shapes prior to plaster/molochite coating. For smaller objects, this material burns away completely, leaving no ash encapsulated in the glass.
The original contribution to knowledge that this research thus offers is the description of new techniques and processes that allow some extension to form in studio glass kiln-forming – especially involving the casting of thinner or higher aspect-ratio forms that might previously have been prone to cracking. Additionally, the processes can (a) reduce the volumes of refractory mould material currently used in traditional techniques, and (b) utilise apparatus that is easily purchased without the need to revert to specialist suppliers, thus increasing the accessibility, and reducing the cost of the new processes to the studio glass practitioner.
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