The invention relates to a coating device for the coating of a size-press roll, paper or board or an equivalent moving base. The coating device includes a revolving coating bar which rests against a moving base. The coating bar extends across the machine width and is supported on a cradle substantially over its entire length. The coating bar spreads and smoothes a coating agent introduced into the coating device and applied onto the moving base before the moving base contacts the coating bar. The coating bar in accordance with the invention is a smooth bar of large diameter, fitted against the moving base so that the profile of coating quantity of the coating agent can be controlled.