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
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.
