| 摘要 |
Disclosed is a system for developing latent images on alkali-based or acid-based paper stock which has been marked with a water-soluble oxidizing agent to form a concealed image. In the system, a marking composition is applied to said paper stock which comprises (a) A water-soluble iodide, (b) Acetic acid, (c) A water-soluble reducing agent, and (d) Water. Preferably, the reducing agent is ascorbic acid and preferably the marking composition also comprises a water-soluble dye.
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