Thermographic processes using polymer layer capable of existing in metastable state

An image-forming process which comprises

• 1. heating, imagewise, to a temperature above a softening temperature T.sub.2, but below the thermal decomposition temperature thereof, a layer that is solid at normal pressure below 40.degree.C. comprising a mixture of a thermoplastic, amorphous, organic polymer of a molecular weight above 10,000 and a normally liquid plasticizer therefor, said mixture being capable of existing
• a. in a metastable state at 20.degree.C. having a softening temperature T.sub.1, and
• b. in a stable state at 20.degree.C. and having a softening temperature T.sub.2 at least 10.degree.C. above T.sub.1 while said polymer is in the latter stable higher softening state, for a period sufficient to convert the stable polymer to the metastable state,
• 2. bringing the entire surface of the layer to a temperature T between temperatures T.sub.1 and T.sub.2, whereby the imagewise heated areas are softened and and will adhere to surfaces, and the remaining areas are firm and non-adherent, and
• 3. converting the softened, exposed image areas to a visible image by adhering to them finely divided particles or the surface of a separate image-receptive element to which said exposed image areas are transferred.