New colours for metal patinas are being developed by researchers Prof. Stephen McNeil and fourth-year undergraduate Ashley Devantier - photo by Tim Swanky

UBC Reports | Vol. 55 | No. 2 | Feb. 5, 2009

New Patinas Bridge Science and Art

By Jody Jacob

Imagine a purple Statue of Liberty, dressed in a canary-yellow robe, holding a bright red flame.

The artistic concept is in the scientific works, thanks to research by Ashley Devantier, a fourth-year UBC Okanagan student using chemistry to create more colour options for artists working with patinas.

A patina is a coloured coating on the surface of bronze or similar metals, often produced naturally by oxidation over a long period -- such as the blue-green colour on the Statute of Liberty’s copper surfaces. Artificial patinas are used by artists to add an antique look or feel to their artwork, but these artificial patinas have their drawbacks: they’re confined to a very limited colour palette (usually blue-green) and often use highly toxic or hazardous compounds.

By mixing and manipulating common -- and far less toxic -- metallic elements and identifying the molecular basis for new colours, Devantier has produced nearly a full rainbow of colours not previously available in the patina palette. In addition, she has studied and analyzed the underlying molecular changes that take place when applying these new patinas.

“I took some common metallic elements -- like chromium, iron, cobalt and copper -- which are known to give compounds with very intense, vibrant colours, and started to explore the chemical processes that occur when they are applied to bronze surfaces,” says Devantier.  “All of a sudden these amazing colours started to show up.”

Although the practical applications are yet to be determined, Devantier’s research could potentially give artists new, less-toxic formulas to create patinas of varyingcolours -- .

Devantier, who received an Undergraduate Research Award (URA) from the Irving K. Barber School of Arts and Sciences to conduct her research last summer, says interest in her work has been overwhelming and the experience itself has been life-changing.

“The response I’ve had from the internal UBC arts community is fantastic,” she says. “Personally, when I look at where I was only a few months ago and where this project has taken me over time, well, it’s mind-boggling. The URA grant has completely changed my personal path and the way I thought about science and research.”

Devantier had planned to finish her Bachelor of Science degree in chemistry by December. She was looking forward to finishing university and was eager to start working -- in whatever field she was able to land a job. But after receiving the URA and completing the research part of her project last summer, Devantier decided to continue with her project through an honours thesis.

“This project has been in Ashley’s hands since day one,” says Stephen McNeil, assistant professor of chemistry and primary supervisor of Devantier’s patina research project. “It is really something off the beaten path. I was surprised to find out that nobody seemed to have done the preliminary work to see what transition metals could be put on a surface to create colour, so it was very exploratory at the start. It’s a visually enticing project that really bridges science and art.”

Currently, as part of her honours thesis, Devantier is studying molecular changes over time occurring on the surface of the bronze patinas, and recording them. The next step will be to approach the arts community to determine the practical applications of the research.

Although the project has been rewarding for Devantier, it has presented interesting challenges.

“There was the great saga of the disappearing red,” she says. “I produced this beautiful bright red and for the life of me I couldn’t figure out how to do it again. I used the exact same mixture, and it would repeatedly turn blue. I was convinced the colour gods hated me.”

A few weeks of perseverance and careful study revealed the cause: solutions of an iron salt would react with the copper atoms in the bronze surface, yielding a red iron compound. If the iron solution had time to react with oxygen in the surrounding atmosphere, the iron complex would oxidize, and form a blue colour instead. Applying the iron under a flow of nitrogen gas would prevent the oxidation, leaving the original red. Chemical identification of the blue and red materials provided the clues needed to reproduce each colour.

“Figuring that out was the most rewarding thing I’ve ever done,” says Devantier.