1. Fluorescent Art Studio Glazes
Felipe Marra-Mateus, Matthew Ray*
Department of Chemistry, University of Wisconsin-Stout
Introduction
Colored glass is important in both aesthetic and safety applications.  Glass applied to ceramics, known as glazes, make dishware more beautiful as well as impervious to water.  Glass for window use is tinted to greatly reduce the amount of ultraviolet light through the window making it safer for our eyes.   These effects are caused by adding metal ion dopants into the glass and glaze recipe.  Visible colors can be created by using transition metals such as iron or cobalt while inner transition metals such as europium or terbium can be added to produce fluorescent effects. The research work presented here examines new metal dopant combinations to produce fluorescent effects in glazes.
Glowing Tiles
The glazes doped with europium chloride and lanthanum oxide showed a red-orange fluorescence under UV-light. Also the glazes doped with silver oxide exhibit a broad emission of light, emitting a white color.
The pictures above show the same tiles in different light environments. The upper row shows europium and lanthanum doped glazes, the second and the third were doped with silver oxide. The blue region over the orange europium glaze was a cobalt oxide doped glazes which produces a blue color in visible light.
Fluorescence Intensity
Using a spectrophotometer it was possible to obtain the relative emission curves of the six most concentrated doped glaze samples. The silver doped sample has a broader emission in the visible light region, characterizing a white appearance. On the other hand, the europium doped glaze shows more narrow emission in the red part of the visible spectrum.
Silver Doped Glaze
Europium Doped Glaze
Objectives
The primary goal of the research presented here was to use a chemistry approach to explore ceramic glaze formulations and impart new and novel color and fluorescence effects in the glass. A related secondary goal is to unify the terminology used to describe glass and glaze compositions and processing temperatures between the Chemistry and Art departments.
The image above depicts raw materials used for glaze formulations in the UW-Stout Ceramics Studio.
The spectra above show the fluorescence emission for the highest 6 glaze samples from each element. Concentrations from 9.7% down to 2.5% of silver is shown on the left and concentrations from 3.2% down to 0.17% of europium is shown on the right.
Behind the Scenes
Fluorescence is a photoluminescence phenomenon where a portion of the light energy absorbed by a sample is re-emitted within a brief amount of time at a lower and less energetic frequency from the original absorbed light.
For our glazes, the UV-light is absorbed and re-emitted as orange light in the Europium doped samples and as a bright white continuum in the silver doped glazes. Fluorescence is distinct from simple light absorbance, as in the case of the cobalt doped glaze, where red and orange photons are absorbed creating the blue color when illuminated by white light.
Modus operandi
The base formulation for this study is called Worthington’s Clear Borate-Silicate glaze, and was obtained from the Stout Art Ceramics Studio. Doped glazes were applied over white clay bisque ceramic test tiles and fired in an electric furnace to 1050°C (or 1922°F) for several hours.
The image above shows the appearance of an example tile before and after firing, respectively.
Acknowledgements
The authors would like to thank Mr. Sean Larson from the School of Art and Design for all his assistance and useful discussions. We would also like to thank Research Services for funding the research work with a student research grant.