What Are The Most Antimicrobial Metals?

Metal is an amazing material, the wide variety of commercially available metal alloys means there is something perfect for every application, whether that’s stainless steel for its anti-corrosion properties, Aluminium for thermal conductivity, or Titanium for incredible strength.

But one thing that you may not know about, is that some metals can actually kill bacteria they come into contact with, meaning they have an inherent antimicrobial property.

What Metals Are Antimicrobial?

There are two predominant metals that are antimicrobial, Copper and Silver. There are many different alloys of each element, used commonly in various industries.

Silver Alloys

Like most commercial metals, Silver is mixed with other elements to enhance its properties, there are 5 main types of silver alloy,

• Argentium Sterling Silver – Approximately 6% copper, mainly used for jewellery
• Platina 4 – 6% palladium along with trace amounts of gold and platinum, again used for jewellery
• Silver Graphite – 3.5% graphite and is used for electric contacts
• Dental Amalgam – 50% mercury 30% silver, 14% tin and 8% copper, used for dental fillings
• Brazing alloys – Copper and Silver, used for soldering of dissimilar metals

Copper Alloys

Copper is used in commercial and industrial applications all over the world, its extremely high thermal and electrical conductivity, combined with ease of manufacture means it’s a great choice for electrical contacts and more.

• ‘Pure’ Copper – around 99.5% pure copper is used in cabling and electrical contacts
• Brass – Copper and Zinc, used for their great casting ability, and where low friction is required, such as locks, valves and musical/measuring instruments
• Bronze – Copper and Tin, are often seen cast into statues and other architectural features, thanks to their ease of casting and attractive colour
• Gun Metal or Red Brass – copper, tin and zinc is a variation of Bronze, with increased strength and a bluish hue

The History of Antimicrobial Metals

Metals have been used for centuries for their antimicrobial properties, silver in particular was ingested by the ancient Greeks to cure various ailments and is still used today – although it is far from an approved form of medicine.

In more modern times silver was used to slow the growth of bacteria in everything from bottled milk to surgical instruments and stitches, providing a vital method of reducing the likelihood of bacterial infection before antibiotics.

Many different ancient civilizations used copper to store their drinking water, as it greatly slowed the rate at which the water turned bad.

How do Antimicrobial Metals Work?

It is not fully understood how copper and silver prevent the growth of bacteria, but the most accepted theory is that the metals release Ions – a group of atoms with an electrical charge – that damage the cell membranes of the bacterial cells.

Once the ions are inside the bacterial cells, they attack essential proteins vital to the cell’s function and cause them to die off.

Uses of Antimicrobial Metals

Advances in water processing and storage mean copper vases and bowls are no longer needed to prevent drinking water from growing bacteria, but copper-based alloys are used commonly in many situations.

Battling Antibiotic-Resistant Bacteria

Antibiotics have been nothing short of a miracle in the field of stopping bacterial infections, and have saved millions of lives since their widespread adoption in the mid-20th century. An issue we face today however, is that some strains of bacteria are ‘evolving’ a resistance to antibiotics and reducing the effectiveness of the medication.

The use of copper-impregnated fabric in wound dressings has been scientifically proven to dramatically reduce bacterial infections such as MRSA. The data shows a copper-zinc Hydrocolloid dressing actually performed better than silver-laced dressings.

Copper Surfaces for Reducing Bacteria Transmission

Testing has also been conducted on the efficacy of Copper rich surfaces for their ability to destroy any transmitted bacterial strains that land on them. The contact between people and surfaces, such as door handles, handrails and countertops, can be a significant transmission method of common bacteria that develop into MRSA and Sepsis.

Testing shows that surfaces made from significant percentages of copper – over 55% – are extremely effective at killing the bacteria present, in many cases completely eradicating the bacteria in less than 90 minutes.

Source: ncbi.gov – Linda P. Arendsen et. al

How to use Copper as an Antimicrobial Surface

If you are thinking of implementing copper into a surface or fixture in your workplace or home, there are a few things to consider.

Copper is quite malleable and soft, and as such wears faster than stainless steel, using brass with a higher percentage of copper makeup can help this as brass generally contains 55% – 95% copper and 5% – 45% zinc and is much more wear-resistant, although it is more expensive.

To buy copper and brass at great prices with unrivalled service, contact your local Metal Supermarkets store for delivery and cutting services.