There is disclosed a process for obtaining a water-borne crosslinkable composition comprising a block copolymer comprising at least blocks [A]x[B]y (where x is an integer from 3 to 80 (inc.), where y is an integer ≧10 and where y>x) and a polymer P, the block copolymer-polymer having an acid value ≦150 mg KOH per g of block copolymer-polymer, where at least block [A] and [B] is obtained by a controlled radical polymerisation of at least one ethylenically unsaturated monomer via a reversible addition-fragmentation chain transfer (RAFT) mechanism in solution in the presence of a control agent and a source of free radicals; and where polymer P is obtained in the presence of blocks [A]x[B]y by an emulsion polymerisation process.