A washing appliance including a wash receptacle and a lid assembly for closing an open top of the wash receptacle. At least a peripheral portion of the lid assembly is movable toward and away from the open top of the wash receptacle between a sealed condition contacting contact portions of the periphery of the open top and an unsealed condition spaced away from the periphery of the open top. The lid assembly is generally rectangular and has front, rear and side portions. In the closed condition the peripheral portion of the lid assembly is urged against the top of the receptacle by forces applied to opposed side edge portions of the lid assembly. Front and rear portions of the contact portion of the receptacle periphery are planar and the peripheral portion of the lid structure is curved across front and rear contact portions, to be closer to the receptacle periphery in central portions of the front and rear contact portions than lateral portions of the front and rear contact portions.