The public conservation of Saint-Gaudens’s Labor Supported by Art and Science and Law Supported by Power and Love in the summer of 2017 was an opportunity to use a relatively new and environmentally friendly technique that is nonabrasive and nonconductive.

Although the process was developed in 1986, cleaning bronze with icy blasts of carbon dioxide was introduced in art conservation only a few years ago. Pellets of frozen carbon dioxide (dry ice) are shot through a nozzle to remove build-up from surfaces safely. For the Saint-Gaudens bronzes, this meant removing accumulated dirt, bird droppings, and old wax coatings that were failing. The warm surface of the sculpture immediately sublimates the ice pellets. (Sublimation changes a solid into a gaseous state without becoming a liquid first.) The ice freezes the unwanted soiling, and the gas separates it from the artwork, producing a smooth, clean surface ready for a fresh coat of protective wax. Despite the soaring outside temperatures in July, the conservators used blow torches to ensure the wax coating went on smoothly.

An added benefit of this form of conservation is that it is environmentally friendly. Since carbon dioxide is a naturally occurring gas found in our atmosphere, it produces no toxic fumes. And because the blasting process returns the gas to its natural state, it leaves no hazardous materials to dispose after the conservation treatment.

Watch the video to learn more.