Silver salt photothermographic dry imaging material

A photothermographic imaging material packed in a packaging material, the imaging material comprising a support having thereon light-insensitive organic silver salt grains, photosensitive silver halide grains, a reducing agent for silver ions and a binder,

• wherein the packaging material has a water permeability of not more than 5.0 g/m2 measured at a temperature of 40° C. with a relative humidity of 90% for 24 hours;
• and the imaging material has a first photographic speed and a second photographic speed and the second photographic speed is not more than 1/10 of the first photographic speed,
• the first photographic speed being derived from a first characteristic curve obtaines from the imaging material subjected to a first image forming method comprising the following steps in the order named:
• (1a) exposing the imaging material to light using an optical wedge under a predetermined condition;
• and
• (1b) applying heat to the exposed imaging material under a predetermined condition so as to develop the exposed imaging material,
• and the second photographic speed being derived from a second characteristic curve obtained from the imaging material subjected to a second image forming method comprising the following steps in the order named:
• (2a) applying heat to the imaging material under the same predetermined condition as (1b);
• (2b) exposing the heated imaging material to light using the optical wedge under the same predetermined condition as (1a);
• and
• (2c) applying heat to the exposed imaging material under the same predetermined condition as (1b) so as to develop the exposed imaging material.