Sweaty Palms Reduce Brass' Anti-Microbial Properties

Sweaty palms can reduce the antimicrobial properties of copper-containing knobs, a new study has found.

According to researchers at the University of Leicester - within one hour or sweat exposure, brass knobs lose their bacteria fighting properties.

Brass contains copper, which is known to be anti-microbial. Hospitals and schools often have brass knobs because they prevent spread of bacteria. Researchers have found that salt and water from peoples' sweat can corrode brass items within an hour of exposure. The corrosion reduces brass' antimicrobial properties.

"The antimicrobial 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 a degradation of the bacteria DNA," said Dr John Bond OBE of the University of Leicester's Department of Chemistry

"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. We have shown that it is possible for sweat to produce an oxide layer on the metal within an hour of contact," Bond said in a news release.

Other research had already demonstrated that sweat can corrode brass. However, this is the first study that analyzed copper erosion due to sweat in the first few hours of exposure.

The loss of anti-microbial properties can be prevented by regularly cleaning the brass knobs and if possible, coating them with a chemical that prevents corrosion, Bond said.

Copper is known to kill several different types of bacteria and is more efficient than silver. Bond said that public places, schools and hospitals can use copper-based items to reduce the spread of disease-carrying germs.

The study," Electrochemical behaviour of brass in chloride solution concentrations found in eccrine fingerprint sweat", is published in the journal Applied Surface Science.