Abstract: To produce a de-foamer, mono- and/or poly-functional isocyanate is reacted with mono- and/or polyfunctional amines, preferably in equivalent ratio 0.5:1 up to 1:0.2, in an organic carrier media, to form urea sols at temperatures which lie below the melting temperature of the resulting urea, the organic carrier medium not being a true solvent for the urea. The prepared ureas are represented by the general Formula 1: ##STR1## wherein r=C.sub.4 -C.sub.30 -alkyl; R'=C2-C.sub.12 -alkylene, phenylene or naphthalene with or without substitution by one or more C.sub.1 -C.sub.9 -alkyl groups, or cycloalkylene; R'--H or CH.sub.3 ; R"--H or methyl; and x=0 to 1, and are prepared by reacting isocyanates with amines in organic carrier media to form ureas of Formula 1, at temperatures lying below the melting temperature of the resulting urea, the organic carrier media not being true solvents for the urea.