| abstract |
An inkless method of recording an image of a desired object or symbol such as the print of a person's finger is described in which a recording surface is prepared by placing thereon a thermosensitive color-developing layer comprising a chromogenic dye such as a leuco dye, an organic acid developer, such as a phenolic compound, reactive with the dye to form a color and a thermosensitive barrier layer separating the dye and developer. A chemical reagent containing one or more metallic slats, such as ferric chloride, in the format of the desired object or symbol, is applied to the recording where the reagent reacts with the developer and/or dye in the thermosensitive color-developing layer to form a permanent two-dimensional image of the object or symbol such as the ridge pattern of the person's finger. |