Sculpture Conservation & Gilding:
While this unusual sculpture conservation treatment was completed in 2014, it is not until now that we can report, with some confidence, its success. This is due to needing a period of years to determine the durability of a treatment of gilding that has had little real-time performance history – catalyzed urethane clear coating on gold leaf in an outdoor environment. In this case a urethane clear coating capable of withstanding the clawing of birds!
While clear coatings on a variety of substrates can provide added protection to a surface, they are used with hesitance because, when they fail, they are problematic to remove. So far so good. Its been a little over 3 years.
Above the surface of the pond on the grounds of the Montgomery Museum of Fine Arts stand three 14-foot gilded aluminum tubes titled 1991-IV by sculptor Edward Lee Hendricks. Each of the graceful arcs balances on a pole sunk into the bed of the pond, allowing it to be moved by the surrounding forces of nature. The movements of the sculpture seem to imitate the movement of the water, the clouds, and even the birds who love to roost on them.
Over time this interaction with nature became detrimentally intimate, resulting, in this case, in a surface scarred by the claws of resting birds – sharp-clawed cormorants tearing away the sculpture’s original surface gold leaf – and spotting it with guano.
And in addition, cracks had developed in the aluminum encircling the welded supporting arms.
All reasonable and potentially more durable alternatives to the original gilding, now mostly gone, were considered and discussed between the conservators and museum. Alternatives such as Kynar or anodizing were eliminated. In the end all parties agreed to returning the surfaces to their originally gold leafed finishes but taking the chance on the bonding and durability of a clear industrial urethane coating.
For treatment, the entire sculpture was removed from its setting and brought to our facility. Once there, welded steel stands were made to hold each tube steady at working height for easy access.
The aluminum was cleaned to bare metal with power tools and the cracks in the tubes were welded closed. Then each aluminum tube was coated with PreKote, a chemical treatment we use for aluminum as a first priming step that would clean the surface, impede corrosion, and enhance the adhesion of applied coatings through forcing the formation of an aluminum oxide optimal for coatings adhesion.
Next, we painted the treated aluminum with a yellow-tinted epoxy primer. It will not only function as a tough layer of protection against scratches from bird claws, its gold color will make the inevitable losses of gold leaf due to scratching and weathering leaf less visible.
At last the sculpture was ready for gilding. A slow-cure size was applied and when it came to just the right tack, 23.75 kt gold leaf was carefully laid over the entire surface and gently brushed to a uniform finish.
Gold leaf, even when outdoors, is very rarely given any kind of protective coating. Gold will not tarnish, it is surprisingly durable, and coatings usually have the unwanted effect of dulling the beautiful brilliance of the gold.
But in cases of high traffic, either from people or birds a protective coating is advisable. After the gilding had hardened – which can take several months – the gold was spray coated with a protective industrial urethane clear coat which was developed for metallic paints to both enhance the finish and extend the long-term weathering qualities of metallic pigmented coatings – it even resists most graffiti markings.
1991-IV was reinstalled in 2014. Back in its home in Montgomery the three majestic curves once again sway gently with the wind and the waves and now shine a bit more brightly in the southern sun. And the sharp-clawed cormorants returned.