{"id":2711,"date":"2021-07-21T17:28:51","date_gmt":"2021-07-21T15:28:51","guid":{"rendered":"https:\/\/moval-srl.it\/?p=2711"},"modified":"2021-08-30T17:31:39","modified_gmt":"2021-08-30T15:31:39","slug":"brass-the-antibacterial-alloy","status":"publish","type":"post","link":"https:\/\/moval-srl.it\/en\/brass-the-antibacterial-alloy\/","title":{"rendered":"Brass: the antibacterial alloy"},"content":{"rendered":"

Hygiene and safety matter in relation to contact surfaces has always been an area to which particular attention should be paid, especially after the pandemic we have been facing over the last year. Microbes and bacteria can settle on surfaces and live for up to 30 days.<\/p>\n

This is another reason why copper and its alloys – such as brass – are used in the manufacture of frequently touched objects (e.g. taps, handles and handrails) as materials with antibacterial and antimicrobial properties, although they are usually subjected to surface treatment.<\/p>\n

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Brass protects against harmful agents: scientific evidence<\/strong><\/h2>\n

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Data emerging from numerous studies (University of Southampton – UK)<\/strong> show that brass and copper alloys have a natural ability to remove harmful microorganisms relatively quickly (in many cases less than two hours!<\/strong>).<\/p>\n

It was shown that at 20\u00b0C on copper (Cu 99.90%) and brass (CW617N) E. coli bacteria disappeared after 75 and 60 minutes<\/strong> respectively, whereas on AISI 304 steel (18Cr-8Ni) the bacterial population takes two days to decrease by 5 orders of<\/strong> magnitude,<\/strong> and then remains almost unchanged for the next 26 days. Polyethylene, in tests lasting 360 minutes, showed similar behaviour to steel.<\/p>\n

One of the most famous experiments took place in 2008 at Selly Oak Hospital in Birmingham (UK), where the amount of bacteria located on the surfaces of frequently touched objects was measured. The objects used in the test were specially made for the experiment and did not present the surface treatment typical of commonly used copper and brass objects.<\/p>\n

The obtained results speak for themselves: brass taps, tables and push plates for doors showed a 90-100% reduction<\/strong> in bacteria compared to similar objects made of \u201cclassic\u201d materials<\/strong> such as plastic<\/strong> and aluminium<\/strong>, or externally chrome-plated<\/strong> objects such as taps.<\/p>\n

Not even silver<\/strong> seems to own the virtuous properties of brass. In tests carried out at room temperature and humidity by Prof. Keevil of the University of Southampton, polyethylene coatings containing silver behaved like the steel control specimens, i.e. they showed no antibacterial properties<\/strong>.<\/p>\n

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How does brass manage to resist bacteria?<\/strong><\/h2>\n

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Brass and copper alloys were the first solid materials<\/strong> to be recognised by the Environmental Protection Agency (EPA)<\/strong> in 2008 for their antimicrobial properties.<\/p>\n

Their antibacterial action<\/strong> is continuous over time<\/strong>, does not require additives to work and does not lose its effectiveness if the product is subjected to abrasion<\/strong>, even repeatedly; in addition, copper alloys work even if they oxidise naturally<\/strong>.<\/p>\n

Copper, which is found in brass, is an essential nutrient for both humans and bacteria but, in high doses, copper ions can cause a number of negative events for the bacterial cell<\/strong>. The exact mechanism is not yet clear, but there are many theories about it. These include:<\/p>\n