A composition comprising; a) at least a first compound of Formula A X- n-R'- m-Rf in which n is either 0 or 1; m is either 0 or 1; Rf is a perfluorinated aliphatic structure, branched, linear or cyclic, in which no more than six fluorine bearing carbons are connected in any single straight chain segment, this structure optionally being interrupted by one or more oxygen atoms; X is a moiety containing at least one group providing binding functionality to a surface to be treated, or containing at least one polymerisable double bond, or containing at least one cross-linkable group; R' is a divalent radical containing at least one group capable of forming polar interactions or hydrogen bonds; L1 and L2 are independently divalent linking radicals which do not form polar interactions or hydrogen bonds and b) a second compound of Formula B X- p-Rf in which p is either 0 or 1; Rf is a perfluorinated aliphatic structure, branched, linear or cyclic, in which no more than six fluorine bearing carbons are connected in any single straight chain segment, this structure optionally being interrupted by one or more oxygen atoms; X is a moiety containing at least one group providing binding functionality to a surface to be treated, or containing at least one polymerisable double bond, or containing at least one cross-linkable group; L3 is a divalent linking radical which does not form polar interactions or hydrogen bonds. a) at least a first compound of Formula A X- n-R'- m-Rf in which n is either 0 or 1; m is either 0 or 1; Rf is a perfluorinated aliphatic structure, branched, linear or cyclic, in which no more than six fluorine bearing carbons are connected in any single straight chain segment, this structure optionally being interrupted by one or more oxygen atoms; X is a moiety containing at least one group providing binding functionality to a surface to be treated, or containing at least one polymerisable double bond, or containing at least one cross-linkable group; R' is a divalent radical containing at least one group capable of forming polar interactions or hydrogen bonds; L1 and L2 are independently divalent linking radicals which do not form polar interactions or hydrogen bonds and n is either 0 or 1; m is either 0 or 1; Rf is a perfluorinated aliphatic structure, branched, linear or cyclic, in which no more than six fluorine bearing carbons are connected in any single straight chain segment, this structure optionally being interrupted by one or more oxygen atoms; X is a moiety containing at least one group providing binding functionality to a surface to be treated, or containing at least one polymerisable double bond, or containing at least one cross-linkable group; R' is a divalent radical containing at least one group capable of forming polar interactions or hydrogen bonds; L1 and L2 are independently divalent linking radicals which do not form polar interactions or hydrogen bonds and b) a second compound of Formula B X- p-Rf in which p is either 0 or 1; Rf is a perfluorinated aliphatic structure, branched, linear or cyclic, in which no more than six fluorine bearing carbons are connected in any single straight chain segment, this structure optionally being interrupted by one or more oxygen atoms; X is a moiety containing at least one group providing binding functionality to a surface to be treated, or containing at least one polymerisable double bond, or containing at least one cross-linkable group; L3 is a divalent linking radical which does not form polar interactions or hydrogen bonds. p is either 0 or 1; Rf is a perfluorinated aliphatic structure, branched, linear or cyclic, in which no more than six fluorine bearing carbons are connected in any single straight chain segment, this structure optionally being interrupted by one or more oxygen atoms; X is a moiety containing at least one group providing binding functionality to a surface to be treated, or containing at least one polymerisable double bond, or containing at least one cross-linkable group; L3 is a divalent linking radical which does not form polar interactions or hydrogen bonds.