Sweaty hands corrode bacteria-fighting brass in an hour

According to researchers from University of Leicester, sweat can cause corrosion of bacteria-protective qualities of brass door-knobs and taps within an hour of contact.

Sweaty hands can reduce the effectiveness of bacteria-fighting brass objects in hospitals and schools after just an hour of coming into contact with them, scientists claimed.

The anti-microbial effect of copper has been known for hundreds of years. It is thought to occur as a result of a charge exchange between copper and bacteria, which leads to degradation of the bacteria's DNA.

"We have discovered that the salt in sweat corrodes the metal, forming an oxide layer on its surface, which is the process of corrosion - and this corrosive layer is known to inhibit the effect of the copper," explained John Bond (OBE) from University of Leicester's department of chemistry.

The team discovered that peoples' sweat can, within an hour of contact with the brass, produce sufficient corrosion to adversely affect its use to kill a range of micro-organisms.

"While it is well known that sweat corrodes brass, this is the first study to quantitatively analyse the temporal corrosion of copper alloys such as brass in the first few hours after contact between fingerprint sweat concentrations of salt and the metal," Bond added.

According to Bond, his advice is to keep the brass in public environments free from corrosion through regular and thorough cleaning.

"In the long term, using copper alloys with corrosion inhibitors included in the alloy at public buildings, schools and hospitals would be a good choice," he added.

The research paper appeared in the journal Applied Surface Science.