Antique Bronze Ltd have secured a £600,000 contract for the restoration of bronze windows on four blocks of the Cripps buildings at St John’s College, Cambridge.

The Cripps buildings, which are student accommodation, have a Grade II listed exterior and the bronze windows were highly disfigured by bright green corrosion. This corrosion had occurred through weathering over time. Much of the original patina had failed entirely but fortunately there was enough of the original finish remaining internally to be able to be sure of their intended aesthetic.

Several teams were involved in bringing this project to fruition on time and within budget. Preparation works to the bronze were undertaken by hand. Although a machine abrasion technique would have been faster, we decided to remove the corrosion deposits by hand which enabled the conservators to make subtle adjustments to the amount of corrosion being removed so that as little of the original surface of the windows was disturbed as possible.

Ultimately, this is a win-win situation – it is better conservation and results in a better finish. When bronze is stripped bright, its aged appeal is lost. A building built in the 1960s, as this was, shouldn’t look like it has just come out of the fabricator’s workshop.

The next stage was repatination. This involves the colouring of the Bronze which is a traditional technique which hasn’t altered in several hundred years. For this project, we mixed a bespoke patina recipe in order to reflect the evidence of the original colour we found on the windows. Finally, the windows were protected with several coats of Renaissance Micro-Crystalline wax, which is one of our preferred products.