Which factor is NOT listed as a determinant of permeation rates?

• A. Temperature
• B. Thickness
• C. Previous exposures
• D. Color

Answer: (D)

Permeation rate through a barrier is governed by how easily the chemical can diffuse through the material, which depends on factors that directly affect diffusion and the barrier’s path length. Higher temperature increases molecular motion and the diffusion coefficient, speeding up permeation. Greater material thickness lengthens the diffusion path and reduces the rate, delaying breakthrough. Color, however, has no influence on the physical or chemical processes of diffusion or on barrier performance, so it does not affect permeation. Previous exposures might influence the material’s condition over time, but they are not a standard determinant of immediate permeation rate. Therefore, color is not listed as a determinant of permeation rates.