In an embodiment, the barrier-forming composition includes a carbohydrate gum, a humectant, and an antimicrobial agent. The composition furthermore meets the following requirements: about 0.01%≦C≦about 0.4%; about 4.5%≦H≦about 65%; and 0.050%<;A; or about 0%≦C≦about 0.4%; about 55%≦H≦about 65%; and 0.050%<;A. C is the carbohydrate gum; H is the humectant; and A is the antimicrobial agent. All percentages are by weight of the total composition. In an embodiment the barrier-forming composition has an Rf value in water of 0 to about 0.25.