Metal containers, such as cans, are printed when empty by means of dye diffusion transfer, the dyes being first printed on to a paper web which is cut into individual carriers. Each carrier is secured, somewhat in the manner of a label, to a container by a water-soluble adhesive so that, upon being heated to effect dye transfer, the carrier comes into intimate contact with a suitably receptive coating, pre-applied to the container, solely by virtue of its own shrinkage. The carrier and adhesive are subsequently removed by water spray.