An electroviscous fluid composition comprising a dispersion medium of two nonmiscible components (A) and (B) as below, the volum ratio of (A)/(B) being in the ratio 99/1 -1/99, and a dispersoid (C)as below; wherein the true specific gravity of the dispersoid (C) is greater than the specific gravity of said component (A) and less the specific gravity of said component (B);
Component(A):
A silicone oil of general formula (I): R a SIO (4-a)/2 (wherein R, which may be similar or dissimilar, are monovalent hydrocarbon groups with 1-18 carbon atoms and "a" lies in the range 1.8
Component (B):
A synthetic fluorinated oil having a viscosity of 1 - 1,000 centistokes at 25 °C and a specific gravity greater than 1.4,
Component (C):
An addition polymer obtained by polymerizing a main component consisting of at least one type of monomer chosen from acrylic acid and its esters or metal salts, and methacrylic acid and its esters or metal salts; is disclosed. In this composition, there is far less sedimentation of dispersoid in comparison to conventional electroviscous fluid compositions.