Abstract: Curtain coater apparatus is disclosed for coating objects wherein the coater head is maintained substantially full of coating material, the material is discharged through an elongated adjustable orifice at a rate to form a stable or unbroken curtain, and an object is conveyed through the curtain at a velocity to deposit a layer of the material of pre-determined thickness onto the object. The heat is provided with a longitudinally split, resilient, metallic, tubular member, with orifice knives carried thereby along the split, one knife being movable by hydraulic actuators with respect to the other knife to define the elongated adjustable orifice. A crank and rack arrangement, carried by the head, is used to adjust the stroke of the hydraulic actuators, and thereby to regulate the orifice width.