Q & A: Saving Face
| Maintaining the iconic sculpture at Mount Rushmore National Memorial in South Dakota is now a complex process, costing tens of thousands of dollars a year. National Parks recently spoke to Jim Popovich, chief of interpretation at the memorial, on the preservation of the site's famous faces. |
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Q: How often do maintenance projects on the sculpture take place?
A: National Park Service maintenance personnel perform an annual inspection of the sculpture each year in September. In 1989 we were raising funds for a complete redevelopment of facilities, and we included the need to do sculpture maintenance on a continual basis and address the preservation of the memorial itself. We completed a structural stability study on the sculpture, using aerial photos and plotting the whole mountain, that identified 141 cracks.
Q: What was the plan to fix the cracks?
A: Sculptor Gutzon Borglum devised a method of patching the cracks with a compound of granite, linseed oil, and white lead. The most damaging effect to the mountain is winter freezing; water gets in the cracks, causing expansion, and it starts breaking down the mountain. We found that the original recipe was more harmful to the mountain because it hardened and shrank too much, allowing moisture to infiltrate the cracks. A silicone caulk was the best material we could find. It's much more flexible; it allows us to add some backing rod material into the crack and fill above that. We can color it or just add granite to it. When we began using the new material, we decided to work on the cracks on the top of the mountain first, thereby keeping water from flowing into the cracks from above and into the faces.
Q: How do you keep track of the sculpture's condition?
A: We determined that there were actually about 21 separate blocks of granite that make up the sculpture. They intersect with most of the 141 known cracks. Then we began a process of monitoring the rock blocks, which will let us see if there are any problems with the mountain. Probes go down into the rock and measure the width of a crack, temperature, and more. Readings each day are sent down to computers, and that information is monitored. We now have installed six rock-block monitor locations on the mountain. We will run data for the next several years, which should tell us if there are long-term problems with the mountain.
Q: How much does that cost?
A: The monitoring system is $55,000 annually. Maintenance work on the mountain itself varies, depending on what needs to be done. Maintenance work usually takes two people, sometimes three. One person goes down the front of the sculpture to do the inspections and the other is available for safety. The [block] monitoring people are also there to repair any of their equipment.
Q: How long does the maintenance project last, and do park visitors see it?
A: We typically perform this activity over a couple of days. The first day is setup and rigging of equipment, plus we use this opportunity to invite media to meet the crew and ask questions. Visitors are given a real treat to see the [maintenance] people scaling the sculpture—it really gives it some scale.
Q: Has there been any memorable damage to one of the sculpture's faces?
A: The only patch of one of the faces was done during the carving process itself, when the face of Jefferson was changed. A crack running across the bridge of his nose and down through his upper lip exposed some granite schist [which was fixed and sealed with sulfur]. The mountain is solid granite, so there's not much that can happen.
Q: Is the sculpture cleaned?
A: We do not clean the memorial. The memorial is exposed to the elements of nature that keep it clean.
Q: Do visitors ask about maintenance?
A: They do, certainly. When visitors first view the memorial, they comment about how immense it is. Second, they begin realizing what it means to our country. Only after these two observations do they begin to understand how it is maintained and what a magnificent feat it was to carve it.
