Thermal transfer printing

A method and apparatus for thermal transfer printing onto selected regions of a substrate are disclosed. The method comprises: a) providing a transfer member having an imaging surface; b) coating the imaging surface with particles formed of, or coated with, a thermoplastic polymer; c) removing substantially all particles that are not in direct contact with the imaging surface to leave a uniform monolayer particle coating on the imaging surface; d) applying energy to selected regions of the imaging surface to heat and render tacky particles of corresponding regions of the monolayer coating; and e) pressing at least portions of the imaging surface and the substrate surface against one another, either during and/or after application of energy, to cause transfer to the surface of the substrate of the particles of the corresponding regions that have been rendered tacky. The monolayer coating can be replenished with new particles and the cycle repeated.