An anti-microbial composition comprising (i) a first compound having a high surface tension of from 20 to 35 mN/m, (ii) a second compound having a low surface tension of from 8 to 14 mN/m, (iii) a first anti-microbial agent and (iv) a polar solvent, wherein the composition acts substantially to prevent the formation of microbial colonies on or at a surface of the composition.