|Care and Maintenance of your Sculpture
General guide. Robert Hague
Forming an invisible protective layer of chromium-oxide, stainless steel resists rust with no further treatment. However over time environmental contaminants such as metal oxides, salts and calcium can stain the surface and if left un-cleaned they may damage this surface layer. Cleaning is a fact of life for stainless steel outside (soap and water) but should staining occur, there are specialised compounds that will instantly return the surface to a bright silver finish.
A bright clean finish can be prolonged by rubbing with dilute oil (70% kerosene / 30% baby-oil) as this will encourage contaminants to wash off.
The most delicate part of your bronze is the patina, the chemically created colouring of the surface. To protect this patina, the sculpture should periodically be dusted, and lightly polished with a plain floor or furniture wax. It is advised that new work should be waxed within its first month and repeated annually.
It should be expected that over time the patina will slowly change. Advice should always be sort for cleaning and restoration.
Also known as Weathering or Austin Steel, Corten is a special alloy that uses copper and nickel to create a weather-resistant surface. This steel can be left untreated but often an annual coating of fine oil will better preserve the rusted surface and halt pitting. It is critical that water not be allowed to pool on the surface for extended periods.
Steel / Mild Steel
Left to the atmosphere, steel will rust. There are two proven ways to stop this:
- Seal the surface: Paints, Waxes and Oils
- Apply an outer layer of protective metal: Metallising and Galvanising
Waxes and oils provide only a temporary coating for steel, and require regular application. They are not suitable for outside work, unless rust is desired.
Paints provide a more durable seal from air and moisture, and given proper care is very effective. Periodic polishing of the painted surface with a fine car wax will dramatically extend the life of the finish and help seal the surface. Paint chips and scratches are best filled with the correct paint, a similar colour or at the very least matching or clear nail polish - to maintain this seal.
Metallising (also known as hot-zinc) is a technical term for the layering of a second protective metal (typically zinc, and similar to galvanising). This metal is applied molten hot, sprayed directly onto the shotblasted steel. It is the most effective long-term protection for steel, with paint over metallised steel providing the ideal corrosion resistance.
NOTE: Some brush painted works use artists acrylics or enamels designed for use inside, these cannot be placed outside and must be kept dry, even when metallised. These paints are professional grade, lightfast and archival, and utilise a 2-varnish (solvent over water-based) system for ease of future restoration.
Aluminium / Aluminum
A light weight (1/3 of steel) and corrosion resistant metal, aluminium is however relatively soft and easily marred. Shallow scratches can be removed with sandpaper to approximate the surrounding surface.
Left to the atmosphere aluminium will form a thin layer of grey aluminium oxide. White powdery spots can indicate damaging levels of oxidation. Consideration must be given to the location and type of fixings used when installing.
To maintain an originally bright silver finish, it is recommended that a regular wax coat be applied (as per bronze). Anodising is an electrochemical process which creates a protective oxide coating which can be clear or coloured. Anodised aluminium needs no treatment and must not be sanded or refinished.
UV damage from direct sunlight, dramatic temperature changes and dampness will all hasten the need for restoration, but given normal care your sculpture should last several lifetimes.
© 2005 Robert Hague
Disclaimer: This information is provided as a general guide only and no liability is accepted for any loss from its use.