Apparatus and method for curtain coating

Apparatus for curtain coating a web or article includes a coating hopper, a support roller, guide rollers for leading the web to and from the support roller and an enclosure. Air which has been conditioned in respect of temperature, humidity and cleanliness is introduced into an upper region of the enclosure. Air flow controlling means are provided below the region into which the conditioned air is introduced. The flow controlling means serve to control the flow of air downwards so that it is uniform across a horizontal plane within the enclosure and has a speed of about 10 feed per minute in the region of the coating liquids in the curtain, that being a speed which will not cause disturbing effects on the liquids in the curtain. The enclosure prevents random air currents of uncontrolled velocity, temperature and cleanliness impinging on the liquids in the curtain and on the slide, which might otherwise adversely affect the product coating. The change of air and the humidity selected for the incoming air keep the humidity within the enclosure at acceptable levels, the humidity tending to increase by virtue of evaporation of the solvent or vehicle in the coating liquid. The air passes out of the enclosure well below the curtain, in the lowest region of the enclosure. The air in the enclosure is at a temperature approximating to that of the coating liquids. In this way condensation of evaporated solvent or vehicle on equipment above and around the liquid curtain, is avoided.