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Two park conservators, standing in a sissor lift, conducting tests on paint on the ceiling of the prismatarium.

Encapsulate and paint gray walls in Aquatic Park Bathhouse Prismatarium

San Francisco Maritime National Historical Park » Encapsulate and paint gray walls in Aquatic Park Bathhouse Prismatarium » Document List

The Prismatarium's ceiling is a color wheel composed of 180 distinct shades, and the room's walls are painted in 10 bands of grey progressing from very dark at the floor to light near the ceiling.

A fine art conservator determined that portions of the paint have broken down and are no longer adhering to the substrate. Testing also revealed that the grey paint has a very high lead content.

The paints and stains used for the colored sections at the very top of the walls and in the ceiling do not contain high levels of lead, and this area has been cleaned without significant loss of original paint. However, it is not possible to treat the grey-painted walls without removing significant amounts of the paint, and any remaining lead-based paint will continue to flake- or dust-off.

The park determined that the best course of action, based on room's planned use as an exhibit space and the continuing lead paint hazard, was to encapsulate the lead paint, and then replicate the grey wall paint design over the original encapsulated paint (once the ceiling conservation has been completed).

A conservator encapsulated the paint using a polymer, Avalure, which is reversible using an aqueous-based solution facilitated by a slightly alkaline pH of about 9. This polymer allows the walls to breathe through the coating while also firmly adhering the paint to the substrate.

Contact Information
Robbyn Jackson
San Francisco Maritime
National Historical Park