Copper is biostatic, meaning bacteria will not grow on it.
During distillation copper can reduce levels of sulphur compounds such as dimethyl trisulphide in the liquid. Copper can do this more effectively in some parts of the pot stills than others. It is not an over all copper effect. Studies have found that the wash still condenser and the spirit pot are most effective at removing this compound. Also, copper stills need to be “worked” to be good at removing these sulphur compounds – new copper doesn’t do it so well.
In damp air copper slowly forms a beautiful greeney blue surface film called patina or verdigris. This forms to naturally to protect the copper from the damp. This effect can be observed on the Islay Whisky Connection logo image.