In his presentation, Michael Kramer from the Gilder’s Studio discussed the treatment of the William Tecumseh Sherman Monument, a gilded bronze statue created by Augustus St. Gauden that currently resides in Central Park, New York. Kramer provided a detailed history of the monument, which was installed in 1903, and a candid explanation of the failures seen on its most recent regilding campaign.
During the life of the statue, the object underwent several campaigns of gilding and toning, often met with disapproval by the public as the resulting appearance was considered too bright and garish. In a 1990 campaign, the monument was regilded and later toned with wax and gelatin. Failures in this coating were noted in 2005 and attributed, by Kramer, to years of collected pigeon excrement that had eaten into the surface.
At that point, Kramer was commissioned by the Central Park Conservancy to regild and investigate stable coating systems that would also provide protection from pigeon infestation. Tests of four different systems were applied to coupons and affixed to the sculpture for a year. The coupons were subjected to real life scenarios to measure performance and assessed using hydraulic adhesion tests. Results showed that while two coats of Butcher’s White Diamond wax with colors in oil proved most visually appealing, its ability to withstand pigeon infestations was questioned. The three coat aliphatic urethane Ronan Aquathane system using a glaze over Japanese colors was aesthetically the second best alternative and performed better than the wax when subjected to the hydraulic adhesion tests.
In 2013, the sculpture was stripped and regilded by Kramer. After curing for two weeks, the toning system was applied. Unfortunately, cracks were noticed in the gilding after only two months. It was discovered that the flaws penetrated beyond the coating system and went as deep as the size layer. Extensive analysis revealed that the formula of the size that was tested five years earlier had changed and was likely the cause of the failures. Kramer emphasized that sometimes, despite efforts to replicate the use of the products and methodology used during the testing phase, things may not work out when in the field, He ended his presentation by sharing useful lessons he had learned: First, lab testing may not translate to real world situations, second, know your product- manufacturers are not obligated to inform users of any formulaic changes and finally, artisans need to ensure the product they tested is the exact one they are using in situ.
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AIC Blog Archives: Conservators Converse
Former Blog of the American Institute for Conservation