A method is provided of processing one or more blades of a row of blades which forms part of a rotor for a gas turbine engine. The method includes: providing a rotor disc having a slot for mounting one or more blades; loading the blades in the slot and loading the wax blocks in or adjacent the slot, the wax blocks being configured and positioned such that, on loading, the blades shear material from the wax blocks, the sheared wax blocks reducing a range of tilt angles which can be adopted by the blades; and performing a processing operation on the loaded blades.