| 摘要 |
A hidden message device and a method by which a hidden message device is produced. A translucent sheet, of any desired color and of any desired material has a hidden message applied thereto by means of a coating material, such as ink, which has the same color as the sheet. Thus, the hidden message portion of the sheet is substantially opaque and/or presents a significant contrast in translucency. The hidden message is not observable until the sheet is positioned between the observer and a source of light. If desired the hidden message may be applied to the sheet in locations among printed material which is applied to the sheet in a conventional manner in a color or colors different from the color of the sheet. Thus, the conventional printed material is readily observable, but the hidden message is observable only when viewed in front of a source of light.
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