Cannon
Restoration

Cannon recovered from the sea are often extensively damaged from exposure to salt water; electrolytic reduction treatment is required to forestall corrosion. The cannon is then washed in deionized water to remove the electrolyte, and is treated in tannic acid, which prevents further rust and gives the metal a bluish-black colour. Cannon on display may be protected from oxygen and moisture by a wax sealant. A coat of polyurethane may also be painted over the wax sealant, to prevent the cannon from attracting dust.
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