What Is Brass?
Brass is an alloy of copper and zinc, the proportions of which can be varied to achieve different colours and mechanical, electrical, acoustic, and chemical properties. Copper typically has the larger proportion, generally 66 percent copper and 34 percent zinc.
Brass is similar to bronze, a copper alloy that contains tin instead of zinc. Both bronze and brass may include small proportions of other elements, including arsenic, lead, phosphorus, aluminium, manganese and silicon. Historically, the distinction between the two alloys has been less consistent and clear, and increasingly museums use the more general term "copper alloy".
What Differentiates Antique Brass From Modern Brass?
Several key aspects, including composition, appearance, craftsmanship, patina, and purpose, distinguish antique from modern brass items.
Tudor brass from 1550, vs modern day brass
Composition and Alloying
Historically, brass's composition has varied depending on the region and period. Older brass might contain varying proportions of copper and zinc, sometimes with additional elements like tin or lead. The alloying methods were less precise, leading to slight variations in the colour and texture of antique brass items.
Modern brass is manufactured with more precise control over its composition, typically with a standard mix of about 60-70 percent copper and 30-40 percent zinc.
17th century brass trumpet-base candlestick.
Appearance and Finish
The appearance of antique brass often has a rich, warm tone with a natural patina that develops over time due to oxidation. This patina can give the brass a greenish or brownish hue, adding to its character and value. The finish on antique brass may show wear, with slight imperfections or irregularities that reflect the past's handmade or less refined manufacturing processes.
Modern brass items often have a brighter, shinier appearance when new, and they are usually coated with a protective layer to prevent tarnishing. The finish on modern brass is typically more uniform and smooth, owing to advanced manufacturing processes and quality control.
Patina and Aging
The natural ageing process of antique brass creates a patina, a layer of oxidation that can enhance its aesthetic appeal. Collectors and enthusiasts often value this patina as it signifies authenticity and age. Patina development can take decades, and the pattern and colouration of the patina are unique to each piece.
Modern brass items are often designed to resist tarnishing, with coatings that prevent patina formation. Some modern pieces are even artificially aged to replicate the look of antique brass.
Modern brass will develop a patina Without these protective coatings, but it will take time, and the process can be different due to the specific alloy used.
An Alloy With a Rich History
While brass has been used in various forms since prehistoric times, its true nature as a copper-zinc alloy wasn’t fully understood until the post-medieval period. This was because zinc vapour, which reacted with copper to create brass, wasn’t recognised as a metal. By the Roman era, however, brass was deliberately produced by combining metallic copper with zinc minerals through cementation, resulting in calamine brass. With various tweaks, this method remained in use until the mid-19th century, when it was eventually replaced by speltering—directly alloying copper and zinc metal—a technique that made its way to Europe in the 16th century.
The European brass industry thrived well into the post-medieval era, bolstered by innovations like the 16th-century advent of water-powered hammers for crafting items such as pots. By 1559, the German city of Aachen was the leading European city for brass production. Eventually, the brass industry took root in England, capitalising on plentiful, affordable copper smelted in the newly developed coal-fired reverberatory furnaces. In 1723, Bristol brass maker Nehemiah Champion revolutionised the process by patenting the use of granulated copper, which was created by pouring molten metal into cold water. This technique significantly increased the copper’s surface area, allowing it to react more effectively, and achieved zinc contents of up to 33% by weight.
Ceremonial brass head, India.
How To Clean And Restore Antique Brass
Antique brass should be cleaned and treated differently than modern brass. This is primarily because antique brass has often developed a patina, contributing to its value and character. In contrast, modern brass is generally more durable and designed to maintain a consistent appearance.
Gentle Cleaning
If cleaning is necessary, use the gentlest methods possible to avoid damaging the patina or brass. Start by simply dusting with a soft, dry cloth to remove surface dirt and dust.
Use mild dish soap mixed with warm water if more cleaning is needed. Dip a soft cloth in the solution, wring it out well, and gently wipe the brass. Avoid soaking the brass or scrubbing hard.
Do not use abrasive cleaners, acidic solutions, like lemon or vinegar, or commercial brass polishes on antique brass, as these can strip away the patina and damage the surface.
Polishing
If you choose to polish, do so sparingly. Focus on areas that need it and apply a polish specifically designed for antique brass with a soft cloth. Always test the polish on an inconspicuous area first.
Many collectors prefer to leave antique brass unpolished to maintain its natural aged look.
Protection
To protect the brass after cleaning, consider applying a thin layer of microcrystalline wax. This can help prevent further oxidation and protect the surface without altering the appearance.
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