A method of encapsulation of an active comprising (a) dispersing an active in an aqueous medium having a pH of less than 6 (b) causing the formation on this dispersed active of a polymer shell, the formation comprising the sequential deposition of a series of polymeric layers, each layer being capable of hydrogen bonding with the preceding layer to form an aqueous slurry of active-containing capsules characterised in that one of the first two layers is a polycarboxylic acid and that the first two to four layers taken together exhibit an interfacial compression dilation modulus of greater than 10 mN/m. The method allows the precise tailoring of polymeric shells, allowing capsules walls to be much thinner without a loss of strength. The technique is especially useful for the encapsulation of fragrances and flavours.
