Historic brass doorknobs have a distinctive beauty and elegance… but I was surprised to learn that some metal doorknobs also have a very practical, natural antiseptic effect. I had no idea that doorknobs can also fight germs!
Of concern is the fact that door handles are instrumental in the spread of many infections. However, some materials, e.g. brass, copper and silver, are slowly poisonous to many germs.
The exact mechanism is not known, but it is commonly thought to be via the oligodynamic effect, or perhaps by some other electrostatic effect. Brass and copper, for example, disinfect themselves of many germs within eight hours.
The oligodynamic effect was discovered in 1893 by the Swiss Karl Wilhelm von Nägeli as a toxic effect of metal ions on living cells, algae, molds, spores, fungi, viruses and microorganisms, even in relatively low concentrations. This antimicrobial effect is shown by ions of brass, silver, copper, iron, lead, zinc, gold, aluminium, and other metals.
Other materials such as glass, porcelain, stainless steel and aluminium do not have this effect.