In this paper, the Casimir force per unit area across a nonlocal slab of an electrolyte between two semispaces of ordinary materials has been studied through the scattering approach. Because of the insu±ciency of Maxwell's boundary conditions, additional boundary conditions are used as well. The numerical calculations show that for polystyrene semispaces at small separations, ascending the concentration causes intensifying the Casimir pressure. However, it is illustrated that in the case of silver substrates the Casimir pressure has the same amount for two electrolyte concentrations and this intensi¯cation does not occur by increasing the concentration. At small separations for polystyrene semispaces, the Hamaker coe±cient has two di®erent magnitudes corresponding to 90 and 0.9mM concentrations, but for silver substrates the Hamaker coe±cient starts from the same value for both concentrations.
