The present invention provides process for the manufacture of an aqueous resin composition comprising a phenolic formaldehyde (PF) resin, which process comprises the steps of providing a formaldehyde and phenolic compound, reacting the compounds in a condensation reaction in the presence of a catalyst, after completion of the condensation reaction to react with free formaldehyde, determining the free formaldehyde content of the resin composition, adding a pre-calculated substantially stoichiometric amount of modifying compound containing a primary amine group to reduce the amount of free formaldehyde in the resin composition to less than 0.1 wt % (relative to the total weight of the aqueous resin composition), and optionally distillation of the reaction product.