Abstract: This invention is directed to the use as coupling agents or bonding agents for fibrous glass substrates of compounds of the formula ##STR1## wherein R at each occurrence is independently an alkyl group of 1 to 5 carbon atoms,X is chlorine or bromine,R.sub.1 is hydrogen, alkyl of 1 to 5 carbon atoms or ##STR2## and Z is selected from the group consisting of ##STR3## WHERE R.sub.2 at each occurrence is independently hydrogen or alkyl of 1 to 5 carbon atoms andP is an integer of 1 to 4, and ##STR4## WHERE M AND R ARE INTEGERS OF 1 TO 3,R.sub.2 has the meaning given above, andY is --S-- or --O--Laminates having excellent resistance to water exposure are obtained when glass substrates treated with the above coupling agents are impregnated with a thermosetting resin such as epoxy and polyester resins.