The Quest for the Golden Ball: Mags Harries and Lajos Héder

Mags Harries and Lajos Hédercreated Drawn Water in 2002 for the Walter J. Sullivan Water Purification Facility at Fresh Pond. One component of this large-scale public artwork is a hollow gold-plated stainless steel ball floating in a tall acrylic water column in the lobby of the building, visible from the walking path outdoors. A passerby drinking from the sculpted bronze water fountain located on the path triggers the water level in the column to drop with rising bubbles, making the golden ball dance in the water. This action, observable from the water fountain, makes visible the public use of water. The golden ball is a measure of the value of this precious natural resource.

Within months of installation, the golden ball began to corrode and was eventually removed for repair. The ball was refinished and re-plated, and a thick layer of epoxy was applied as a protective layer. This second method proved ineffective, however, and the ball again deteriorated, with large patches of corrosion and isolated areas of rust appearing on the surface.

What happened?

The ball was removed to the studio of CAC conservator Rika Smith McNally for examination, and members of the staff of the Water Treatment Facility provided a water quality analysis report that included pH and chlorine content. Under magnification with a binocular microscope, the conservator found small fissures and tiny holes in the gold layer. The epoxy coating had lifted up in isolated patches and was holding puddles of water next to the metal surface. A layer of nickel beneath the gold from the electroplating process was visible over the stainless steel substrate. Corrosion had occurred, and there were a few isolated areas of apparent rust, possibly from fabrication pins or from metal transfer from an iron or steel support used to hold the ball during production. Very small flecks of gold were lifting up from the surface, stuck within the epoxy.

Rika next brought the golden ball to MIT metallurgist and failure analysis expert Ron Latanision for a consultation. Together they quickly diagnosed the problem. The degraded condition of the ball is an excellent example of dissimilar metal electrochemistry resulting in galvanic corrosion (a type of corrosion that occurs when two different metals are in close contact within an electrolyte, in this case the water).

Although the stainless steel ball was fabricated well, the plating process had resulted in three layers of different metals (stainless steel, a nickel intermediary layer, and the gold layer) to be next to each other. The small pinpoint imperfections that occurred in the plating allowed corrosion of the less noble metal (the nickel and/or iron) to occur.

In galvanic corrosion, the more noble metal acts as the cathode, the less noble metal the anode, and the anode corrodes quickly. The gold acted electrochemically as the cathode, the nickel and/or steel acted as the anode, and the anode corroded at a faster rate.

The solution?

With a diagnosis in hand, the conservator and the artists can now consider a few possible solutions for a new ball. As recommended by the metallurgist, re-fabrication of a ball made from different materials is indicated, and Mags and Lajos must bring their original vision to bear on a new conversation about material choice.

As a first step in this process, the conservator is researching the possibility of applying a very thin conductive surface layer to a rigid plastic ball, and using that surface to attach a layer of gold plating. Second, she will be looking for a plastic sheet, possibly tinted with titanium that would look like plated gold, to fabricate a corrosion-free replacement ball. The findings will be presented to the artists for them to make their next material choice.

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