This invention discloses a surgical prep solution formulation, either film forming or non-film forming, that changes color upon a change in pH to indicate that the solvent has sufficiently evaporated. The major components of this surgical prep solution include: antimicrobial agents, solvents, pH adjusters, color changing pH indicators, and optionally: film forming polymers, dyes and viscosity regulators. The pH of the solution may rise or fall depending on the pH of the original solution as compared with the normal pH range of the acid mantle of the human skin or the normal pH range of a sterilizing solution. As the pH changes, the pH indicator may cause the surgical prep solution to change color. Concurrently, as the fluids evaporate, the pH indicators interact with atmospheric CO2, causing the solution to change color based on the pH of the solution. The solution may also be used as coating for medical devices.