The friction coefficient for ice, without a liquid film on the surface, is measured to be formula_43. A comparable friction coefficient is that of rubber or bitumen (roughly 0.8), which would be very difficult to ice skate on. The friction coefficients needs to be around or below 0.005 for ice skating to be possible. The reason ice skating is possible is because there is a thin film of water present between the blade of the ice skate and the ice. The origin of this water film has been a long-standing debate.