Abstract: The gasket-engaging sealing rim of the solids collection vessel of a filtration apparatus is provided with means for cooling its gasket-engaging surface to a stream condensing temperature, and means is provided to direct a flow of steam or other source of water vapor over the gasket-engaging surface while the surface is disengaged from the gasket during discharge of filtered solids, thereby wetting the surface while it is exposed to the atmosphere. This wetting of the surface prevents the accumulation of solids on the surface by the evaporative drying thereon of filtrate solutions, which may come in contact with the surface during the filtration operation.