Cracks in slate, soapstone, or cement laundry tubs are made water-tight with a mixture of litharge and glycerin or a specially prepared commercial cement. The litharge and glycerin are mixed and stirred to form a smooth heavy paste free from lumps. The crack should be cleaned out to remove all grease and dirt and the paste should be worked into the crack with a case knife. A paste of portland cement and water, or of the white of an egg and fresh lump lime, has been used successfully for this purpose.