The Chemistry of Doorknobs

People in the past weren’t dumb. At least not all of them.

We often think they were, which is why we are always changing things and modernising things.

But sometimes our attempts at modernising are actually a backward step, and we come to realize that in years gone by people really did know what they were doing.

Take doorknobs for example.

Any old house will contain brass doorknobs, but we have now replaced them with much more flash looking polished stainless steel or any number of coloured plastics.

We understand that in the past people used brass because it was simple and cheap, looked good, and didn’t tarnish. In our cleverness we’ve now replaced it with things that are cheaper, look better, and don’t corrode or tarnish.

But is that all there is to doorknobs?

Well, aside from allowing us to close and open doors, doorknobs have another, very unwelcome, role in our lives – the transmission of disease. If someone has sneezed onto their hands, and they touch a doorknob, the germs and bacteria are quite happy to sit there until some other unsuspecting soul uses the same knob.

And here’s where brass has it all over any other doorknob material. Brass of course contains copper, which has natural antimicrobial activities and is the active component in many garden fungicides and biocides. Consequently, any germs that find their way onto a brass doorknob don’t last long – it is deadly to most of the common disease–causing germs and bugs. To achieve the same thing with other doorknobs you’d have to spray your doorknobs – every time they were used – with a disinfectant.

So next time you’re shopping for doorknobs and you see those gold-yellow items twinkling innocently amongst the much more flash-looking polished stainless and plastic knobs, just remember, there’s more to doorknobs than meets the eye.

Or next time John Cleese asks “All right, but apart from the sanitation, medicine, education, wine, public order, irrigation, roads, the fresh water system and public health, what have the Romans ever done for us?” we can now answer “they gave us brass door knobs.”