Abstract: An improved sealant for sealing leaks in pipelines and refrigeration and air conditioning circuits includes a partially hydrolized tetra methoxy silane along with another organo silane sealant. The use of a partially hydrolized tetra alkoxy silane, such as partially hydrolized tetramethoxy silane, in place of an unhydrolized tetra alkoxy silane, gives a stronger and tougher and more elastic seal, and the partially hydrolized material is less toxic than the unhydrolized material.