The skin is not a sponge. You do not get 100% of base product to perentrate the dermal layer with DMSO.
DMSO easily penetrates the skin (176 ± 42 g/m2/hr) compared to, for example, water (14.8 ± 0.1 g/m2/hr), but because of DMSO’s low toxicity (see previous section) and the fact that this same permeability test showed DMSO does not carry less-permeable substances with it through the skin, it can be concluded that DMSO does not pose a significant threat by skin absorption. The penetration rate of DMSO in solutions is a direct function of the mole fraction of DMSO. (Ursin, et. al. 1995)14. Although DMSO readily penetrates human skin in concentrations of 70-100%, at concentrations of 67% or less, DMSO molecules are hydrated, which greatly reduces dermal penetration (Sulzberger et. al., 1966; Brayton, 1986: Woodford and Barry, 1986).