Our guest blogger today is Abbott Nixon, IMA Volunteer Intern in Objects Conservation.
Before coming to the IMA as a volunteer conservation intern, I worked in a cozy, climate-controlled painting conservation studio in Buffalo, NY. I thought my work here would be similar, however I quickly found this not to be true and that my primary task of assessing and conserving the four artworks on loan to IUPUI would require hours in the hot, blinding sun.
At the beginning of the summer I set out to photo document each one: Spaces with Iron, Mega Gem, Portrait of History, and East Gate/West Gate. From this day of documentation I created detailed condition reports. From there, IMA Conservator Richard McCoy, and fellow conservation intern, Nicole Peters (of recent IMA Blog fame) and I returned to campus to wash all four and then wax the two bronze artworks. By that time summer was in full swing and the 90 degree day with clear skies made for some pretty interesting (and sweaty) work.
Never having waxed a bronze in my life, I read up on the subject to prepare. Patrick V. Kipper’s The Care of Bronze Sculpture breaks down each step in process of waxing a bronze artwork, as does the IMA blog from last year, Caring for Bronze in the Community. It seemed easy enough. Some light blow torching, applying wax, smoothing the wax out evenly, applying the blow torch again, et voilà! You can imagine it was not so simple. At ten in the morning the sun was already scorching hot. Cleaning Will Horwitt’s Spaces with Iron proved difficult when the water was evaporating faster than we could rinse the suds away.
After scrubbing off grime and bird guano from the artwork, we added heat to the already hot day with the help of a large propane torch. Monitored by Richard, Nicole and I created an efficient team, with one of us heating the metal and the other waxing the surface. At first I was a little unsteady with the large blow torch so I worked as the waxer, however my fellow intern Nicole did not share my jitters and helped out immensely.
Once finished with Spaces with Iron there was a great sense of satisfaction … for about one minute, then we remembered we were about to do this all over again with the Zhou Brother’s Portrait of History. Unlike the smooth surface of Spaces with Iron, Portrait of History has a mottled texture which proved difficult not only to clean but to wax as well.
After finishing Portrait of History, the next day we moved on to washing John Torreano’s Mega Gem. Seemingly straightforward, Mega Gem required a simple washing with Orvus soap. After it was cleaned, Richard decided that the streaking on the piece made it look uneven and rather grimy.
The most straightforward way to remove this staining was to clean the entire surface with mild scrubbing pads. A quick detour to a hardware store procured the scrubbing pads and off to work we went removing the dark streaks of aluminum oxide. Aluminum oxide develops naturally on all uncoated aluminum surfaces. Though it does reduce the metallic sheen of aluminum, it also prevents other more unsightly corrosion from occurring.
Our final stop was at Sasson Soffer’s East Gate/West Gate. The 30-foot-tall stainless steel sculpture was not in great need of cleaning: only the lower portion had areas of visible rust staining (iron oxide). Never working with outdoor sculpture, I was intrigued by the development of this corrosion product. Stainless steel is supposed to be stainless, right?
It turns out that similar to the aluminum oxide layer that develops to protect aluminum, stainless steel has a layer of chromium oxide which provides the “stainless” element that other iron alloys do not possess. If the protective chromium oxide layer is damaged, rust (iron oxide) will begin to form. The chromium oxide layer will regenerate in the presence of oxygen, however if some other element gets there first – like chloride ions – the protective layer will fail to regenerate, giving way to the development of iron oxide.
The Getty Center put together a wonderful book on outdoor sculpture conservation, Conserving Outdoor Sculpture: The Stark Collection at the Getty Center. The book describes a test study about the removal of rust from two of their metal artworks, George Rickey’s Three Square Gyratory and Robert Adams’ Two. This spurred my interest in creating my own test to remove the rust on East Gate/West Gate. We used the commercially available CLR, Super Iron Out, and Bar Keepers friend (phosphoric and oxalic acid-based products) and a solution of 10% phosphoric acid solution that was made in the conservation lab.
The idea was to test the harsher acids and their safer counter parts. We tested two areas: one of light rust build up and one of heavy rust build up. All four products were applied with cotton and left to set for 20 minutes.
The result revealed that, phosphoric acid and Bar Keepers Friend were the most successful at reducing the rust. In the end, we chose Bar Keepers Friend as the most appropriate product because it was much more mild than using the phosphoric acid, (it is an eye and skin irritant), also it can be potentially hazardous if inhaled. We ended our day there – perhaps in the future these test results will help inform a more complete treatment of East Gate/West Gate.
For now, I can walk away from this project with the knowledge that I set out to gain at the beginning of the summer. Having now washed several outdoor sculptures, waxed bronzes, and developed a testing methodology for unknown products, I have a wealth of knowledge to take with me into my next conservation venture and beyond.