Tarnish + Shine

DSCF5582For what feels like forever, we’ve been working on a new public artwork on the Calgary river pathway called Delta Garden + The City Unseen. We were awarded the contract almost 3 years ago, and the installation and surrounding Park are finally scheduled to Open over the coming month.

We’ll admit to a certain amount of anxiety, spurred in part by the Public Art debacle of Bowfort Towers. We want to give Delta Garden the best chance of success as an artwork existing in public space, while minimizing the possibility of receiving hate mail for making public artwork in the city of Calgary.

DSCF9923But there’s a hitch: the duration of install, heavy machinery, and a long winter have had their toll on the artwork. The fresh monuments were shiny and glittery. But many are now tarnished, brown with oxidation.

Polishing tests on tarnished monuments

We expected the monuments to tarnish (the patina is beautiful and dynamic) but we want the artwork to tarnish more slowly, beginning shiny and transitioning towards reds and browns that accompany the weathering of brass.

Part of the concept behind this artwork is the potential that pedestrian foot traffic will wear popular routes into the brass markers, creating polished “desire lines” through the park.

Civically-funded public artworks always come with compromise, balancing aesthetics against pragmatism. Conceptually, it’s important to us that the public bear witness to the full ‘lifecycle’ of the material. We balanced the labour against the experience of the artwork, and decided that polishing is worth doing, even if it only lasts for so long. With the Park’s Opening looming, shining Delta Garden + The City Unseen will give the artwork its best chance for success.

IMG_0880.jpgWe tested various polishing methods. A mild acid like lemon juice + water works well for polishing the brass, but can discolour the surrounding concrete. Water + red scotchbrite pads worked just as well, abraiting the thin patina on the surface of the brass.

We spent an afternoon with a group of (awesome!) volunteers, testing this method. After a few hours, it became evident that the work of polishing 12,000 monuments (without giving all our friends Carpal Tunnel Syndrome) will benefit from more than elbow grease. Power tools were invented for just this reason.

IMG_0900We’d initially written off polishing power tools as too expensive and labour intensive. Wet polishing with a drill chewed through consumables at an unsustainable rate. However, dry sanding with a pneumatic die grinder worked wonders!

DSCF0684DSCF0677Having found a successful process for polishing the monuments, we added a buffer against tarnish, waxing each monument with Trewax. From our research, this will help the brass stay shiny, at very least until the park opens to the public, while also allowing it to tarnish naturally over time.

To date, we’ve only polished one tiny section of the park (about 600 monuments). Over 11,000 more to go! Wish us luck.


While polishing Delta Garden has come with some surprises, there is one unexpected benefit from the monuments tarnishing all winter: the text on the polished monuments has darkened, making the writing more legible from a standing height. Taking a moment to re-read text submitted through the Invisible City Survey has been a real pleasure. We’re curious to see how people respond to the Delta Garden when the park opens to the public – artwork, landscape architecture, social space, and all!


Copyright Statement - Invisible City Survey

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