The exterior wrought iron and steel case screws and fixings were showing signs of oxidation.

The rusted case parts were soaked in a solution containing tannic acid, made with tea bags at approximately pH6. These were then carefully brushed by hand with a soft brass brush, to remove all traces of rust, and rinsed, firstly in water, and then in alcohol.

Next they were cleaned in a propitiatory spirit-based cleaning solution, before being rinsed again in a spirit-based rinse.

After treatment much of the original surface finish was intact and visible. These surfaces were then treated with a cellulose lacquer or a wax-oil solution to help prevent further oxidation.