An example electrostatic machine includes a number of stator plates, each having a stator electrode and rotationally fixed to a housing, a shaft at least partially defined within the housing and configured to rotate about an axis, and a number of rotor plates, each having a rotor electrode and rotational fixed to the shaft. The electrostatic machine includes a dielectric fluid disposed in the housing, and that fills a gap between the stator plates and the rotor plates. The electrostatic machine includes a seal associated with the shaft, where the seal includes a material compatible with the dielectric fluid.