Dusting cloths: tear old cotton flannel sheets into squares. You can do this to sheets in your own rag-bag, or buy sheets at the charity shop. Old towels work well, too. They can be washed and re-used for quite a while. Old cotton knits work fine, if you don’t mind waving your dingy old tightie-whities and sweat stained tees around.

Anything soft and slightly fuzzy, and if the cloth alone doesn’t do the trick all you have to do is get it damp with plain water.