Conservation in Action: Juno, Moldmaking, August 2012

Relocation and conservation of a Roman sculpture of the goddess Juno, early second century A.D.:
August 2012, Moldmaking

Workers (from Skylight Studios Inc.) set up operations in the gallery to prepare molds of the head and neck. The molds will be used to cast lightweight, fiberglass replicas, which will serve as working models in the conservation process. The proper position of the head will need to be determined before conservators can reattach it at nearly 15 feet off the ground. The model head will also be used to experiment with loss compensation of the nose and lips.

First, the marble surface is coated with a mold release agent in order to allow easy separation of the mold from the stone. RTV (room temperature vulcanizing) silicone rubber is then applied to the surface by hand. The first layer is thickened to a specific viscosity to capture the surface details, and much care is taken to avoid trapping any air bubbles. Additional thicker layers of silicon are later built up.

The soft and flexible silicone skin is encased by a three-part plaster mother mold to hold it in the proper position. Below, the first two parts have been applied against the back of the head.

The plaster shell is completed at the front of the head, and both shells are reinforced with metal rods for structural stability.

After unmolding, the silicone rubber is cut along the seam line and peeled away from the marble. The mold now contains every detail of the marble head in negative format.

See next update.