This article examines the restoration and conservation of a large, multi-piece outdoor sculpture. The pieces consist of 20 pieces of sandstone. Many pieces have low relief carvings. A figure and four vegetal forms are the focus of the piece and stand in the center of the entire sculpture. (See original photo) The information is presented as a timeline interspersed with technical, administrative and philosophical issues.
August 1995 - The Need
A condition report was commissioned by the New Mexico Arts Division of the New Mexico Office of Cultural Affairs. The report outlined the history of the sculpture, the physical setting, its condition, and its physical setting. The sandstone sculpture was originally a planter at the Sandia School for Girls (now Sandia Preparatory School). It was then moved to New Mexico Technical Institute in Socorro around the early 1960’s.
March 1996 - Relocating
The sculpture was relocated to storage area on the New Mexico Technical Institute campus to allow for expansion and remodeling of a nearby building. At this time the idea was to relocate the sculpture inside the new building. In order to move the pieces individually, the grout had to be removed. This was a time consuming and arduous task. After all the grout joints were loosened, the pieces were moved with a crane and loaded onto a flatbed for transportation. Special crates were designed to move the more fragile pieces of the statue.
September 1996 - Ownership
During the period between March 1996 and September 1996 the alumni of Sandia School for Girls that is still active heard that the statue was put in storage. A campaign by Sandia Preparatory School to relocate and eventually transfer ownership of the sculpture from New Mexico Tech to Sandia Preparatory School was begun. An appraisal of the art piece was performed by an outside appraiser to establish the value of the sculpture. This information was used to validate conservation expenses.
April 1997 - Relocation
The entire sculpture was relocated to Sandia Preparatory School and the main figure and four vegetal forms were displayed in the school’s theater. The remaining pieces were stored in a covered, exterior area. This storage structure kept the pieces from getting wet and still allows for ventilation of the stone.
October 1997 - Restoration and Conservation
The main statue and four vegetal figures were relocated to studio for restoration work. The other pieces of the statue will be restored when funding is secured. Stone core samples were tested to determined petrographic characterization, water solubility, acid solubility, water absorption, hygroscopic moisture uptake, and anionic salt analyses. The results of these tests directed cleaning methods and consolidation methods.
• Cleaning Methods
Although testing directed and determined cleaning methods, methods were tested in inconspicuous areas beginning with the gentlest cleaning methods first . This first test was a washing with a nonionic surfactant and low pressure water. This had no effect. Other methods were experimented with but as with most cases, the paint, tar, and other surface and subsurface staining was so embedded (in general the longer a staining agent remains on the surface the more difficult it is to remove) that a heavy duty paint stripper formulated specifically for restoration had the best overall effect.
• Stain Removal
The product used to remove surface and subsurface staining contained potassium hydroxide and dipropylene glycol methyl ether (toxic stuff!) The product was applied to the surface (it comes as a thick gel) and covered with plastic to keep it from drying on the surface. The gel remained on the surface for 24 hours and was then removed with medium pressure wash. Acetic acid was used to neutralize the surface and rinsed thoroughly. If the surface was not to be neutralized, an alkaline residue may be left on the surface. This effectively removed all the surface and subsurface staining. Unfortunately, this process removed the patina the stone had developed as well. A new patina will develop, eventually.
• Fill Composition
The face of the statue had severe damage as a result of vandalism, that were probably from strikes with rocks and bullet holes from guns. The holes were filled with a restoration mortar consisting of caulk, sand and iron oxides. Fill composition issues highlight one of the big philosophical debates in restoration and conservation. Some conservators believe as little intervention as possible should occur. In other words, stone loss areas should not be filled in, just stabilized. The other extreme would be to make repairs so it would not be clear what was new and what was original. Issues about repair are complicated when sculptures change ownership. In this case, major stone loss areas were filled but filled so that upon close inspection fill areas could easily be identified. In the future better fill materials may be identified and the statue may be treated with these new and better products and processes. In general, the philosophy behind what to repair and what to leave alone should be performed on a case by case basis.
The most difficult component of the stone fill process was the color matching. As with all types of mortars, the amount of water used, the atmospheric conditions during repair and curing, as well the future sun exposure can have very different results even on the same piece.
• Stone Consolidation
The final step in restoration is actually a conservation measure to keep the stone from deteriorating more in the future. A stone consolidate was applied to the surface. In effect, what this does is fill the pores in the stone matrix to add another layer of protection from wind, pollution, blowing sand, and other damaging weathering effects.
May 1998 - Temporary Home
Restored pieces were installed on a concrete base in the main quadrangle of the school.
In conclusion, a broad knowledge of chemistry, the dynamics of structures, a basic understanding of building materials and their methods of application, art conservation, and patience is required to complete projects of this nature.
Charlene Brown, AIA, Conservator, has a Master of Architecture degree and has a private practice focusing on the re-use, restoration, and conservation of building materials.