Tips and Advice on Cleaning Antique Metal including Antique Gold, Bronze and Pewter
When caring for antique metalware, you should always consider how different metals react in different ways to natural conditions methods of cleaning antique metal should vary accordingly.
Despite their apparent toughness antique metalwares can be scratched, dented and some can corrode easily.
If antique metals are combined with other materials, as in antique jewellery or furniture your care and cleaning should fit the requirements of the weakest material.
If possible you should detach metal parts form other materials, such as sculpture and try cleaning antique metals separately.
Caring for Antique Gold, Bronze, Spelter, Brass and Lead
Caring for Bronze Antiques
The dark or greenish brown patina that forms on bronze is highly desirable and should be preserved; so don’t use metal polish or solvents on any bronze or any water on indoor bronzes. Dusting alone should suffice.
A dull patina can be revived by a very light coating of microcrystalline wax. Always make sure you test an inconspicuous area first to ensure the patina is stable as an artificially induced or painted patina may not be stable.
Apply the wax with a soft bristled brush and burnish gently with a soft cloth.
Archaeological bronzes or items that have been exposed to salty air may develop ‘bronze disease’ – small powdery green spots on the surface. You can wax a small area immediately but anything more serious should be taken to a conservation specialist or professional restorer for specialist treatment.
Tips on Caring for Antique Copper and Brass.
The patina that forms naturally on copper and brass is a much sought-after and valuable asset.
Brass carriage clocks for example, should never be cleaned with metal polishes.
Copper tarnishes to brown and corrodes to a relatively stable green patina; brass eventually acquires a matt greenish-brown surface.
Both Copper and Brass Scratch Easily.
Regular light burnishing with a soft cloth or chamois should be adequate, or use a long term silver polish for light tarnishing.
For heavier stains long term brass and copper cleaners or impregnated wadding can be used.
Tips Caring and Cleaning Antique Gold
Make sure you establish whether your gold item is solid, plated, silver-gilt or ormolu, as gold is soft and the thinner the surface layer the more easily it will be rubbed away.
Gold also scratches very easily, but doesn’t tarnish unless it has a high silver content, as with some 9ct gold.
Light dusting will usually be enough, but gold objects can be washed as long as no weaker materials such as porous gemstones are present in the piece.
Tips on Cleaning Iron & Steel Antiques
If exposed to damp, iron and steel will rust rapidly and will then pit, flake and eventually disintegrate completely.
Cast iron and wrought iron can be given a barrier coating of paint or graphite, but overpainting the original finish may reduce values.
A microcrystalline wax or light penetrating oil are suitable for steel.
Bear in mind that direct heat cracks paint, so iron grates and fire backs that are in use should be black leaded.
Before cleaning iron or steel, make sure the metal is absolutely dry, if the object is tough enough remove loose rust and paint with wire wool or a wire brush followed by a commercial rust remover or wire wool soaked in paraffin.
Wipe clean and dry thoroughly then coat with a commercial rust inhibitor.
Remove minor rust spots with a mild abrasive cloth and a few drops of a light penetrating oil or gently scrape them off with a scalpel. Methylated spirits or white spirit are also useful cleaning agents.
Severe rust needs professional treatment such as sandblasting or chemical stripping to restore the surface to good metal before a protective coating can be applied.
Caring for Lead Antiques & Figures
Lead is heavy but very soft, easily dented and scratched.
It is also poisonous so always wash your hands after handling.
Corrosion appears as a white powdery coating.
Regularly dust lead antiques kept indoors.
A sound surface can be cleaned with a soft bristled brush or cotton wool moistened in water with a few drops of non-ionic detergent added. Rinse immediately and dry well.
Microcrystalline wax helps to prevent further deterioration: apply one or two coats (leaving an hour between each) and buff gently with a soft cloth.
Tips on Cleaning & Caring for Antique Pewter.
Pewter is easily dented and scratched.
Antique pewter usually has a high lead content that reacts and corrodes more quickly in acid conditions, so avoid keeping the metal in oak furniture that is particularly acid, and always wrap in acid free materials for long term storage.
Whether you prefer pewter to be allowed to develop a matt tarnished surface or polished to a silvery finish is up to the you as the owner.
A dull gleam introduced by regular, light buffing with a dry cloth is a good compromise.
If the surface is heavily stained or very dull, try gently wiping it with a rag impregnated with linseed oil and talcum powder.
Remove this mixture with cotton wool swabs moistened with methylated spirits and then wash, rinse and dry thoroughly.
If watery spots or powdery corrosion appear; usually caused by the lead reacting with the acid in the atmosphere, pewter should be treated by a professional metal restorer
Caring for Antique Spelter Figures
Spelter is softer and more brittle than bronze and is prone to corrosion about which very little can be done.
Figures are often thinly cast and fragile, so alwyas make sure you hold them at the most solid part.
Painted or gilded figures should not be allowed to get wet but should only be dusted lightly with a soft haired artists brush.
Unpainted spelter can be waxed in the same way as bronze.
General Cleaning Techniques for Antique Metalwares
- Always cover your work surface with a soft cloth and always try to wear clean cotton gloves as fingerprints can leave deposits that can cause tarnishing.
- Before cleaning any item, check for loose parts or splits in the metal.
- Use proprietary of the shelf, metal polishes as little as possible as they work by removing a small amount of metal.
- Dust regularly with a soft cloth and use a soft bristled brush for awkward places, it reduces the need for major cleaning.
- For grime or light tarnish on metals, except for bronze and iron, wash in warm water with a little mild detergent added. Only immerse your object if it is all metal with no weaker materials. Cotton buds are useful for getting into and cleaning small areas. Always rinse the item and dry thoroughly with absorbent paper.
- Never put precious metals in a dishwasher as the salts and detergents may pit and stain the surface.
- For heavier duty cleaning on antique brass and copper only, you can use long term metal polishes that have a built in tarnish inhibitor.
- Firstly, use a soft brush to remove dust and dirt that can scratch the surface if rubbed against it. Never be tempted to dislodge stubborn stains from metal with wire wool or an abrasive cloth. Then apply your cleaner with a soft cloth or soft brush in gentle circular movements. Rinse and dry the item once with an absorbent paper towel and remove polish from crevices with a dry soft brush.
- Seal antique silver, copper and brass against corrosion with a lacquer. Remember though that this not only stops the item obtaining a patina but the lacquer is easily scratched and marked by fingerprints and it can soon look patchy.
- Lacquer is worth considering for display items with intricate decoration that would wear away with too much cleaning.
- Use a light coating of microcrystalline wax applied after cleaning as an effective and less radical barrier than lacquer.