US2093397A - Process of producing invisible writing - Google Patents

Description

Patented Sept. 14, 1937 2,093,397

UNITED STATES PATENT OFFICE PROCESS OF PRODUCING INVISIBLE WRITING John Wesley MeCulloch and Chester H. Myers, Monroe, Oreg.

No Drawing. Application March 1, 1937, Serial No. 128,547

2 Claims. (Cl. 41-20) Our invention relates generally to means for writing indentations on the wet sheet entirely disproducing invisible writing on surfaces, and parappear. ticularly to a process of treating a sheet of paper The resultant wet sheet which is no longer or the like to produce invisible writing thereon, wet, can in this processed condition be either 5 which writing can be restored to visibility at will stored or mailed or otherwise handled.

and rendered again invisible, and an important When it is desired to cause the writing on the object of our invention is toprovide a process of Wet sheet to reappear, this wet sheet is placed this character which is simple, efiicient, and me in a basin or trough of water, whereupon, after expensive and wherein a permanent record is elapse of a short time, the original writing on the available. wet sheet will become visible. 10

Other important objects of our invention will After the writing has been caused to re-appear be apparent from a reading of the following deand he p rpo e f u h reapp r having scription taken in connection with the example been Served, the Sheet can then h P given for illustrative purposes, away to dry and the writing will disappear again.

The process of the present invention contem- Thereafter whenever it is desired to cause the 5 plates the production of invisible but restorable writing to become visible the wet sheet is placed Writing upon sheets of ordinary paper, so that the in water as described above. The production of sheets may be utilized as and stored as perthe ppe e a d the production of the pmanent records in which the invisible writing may pearance of the writing may be repeated an inbe restored at any desired future time and again definite number of times with the same wet 0 rendered invisible. sheet.

The embodiment of the present invention con- Although we have shown and described herein templates a process wherein an ordinary sheet of a p e ed embodiment of the Process of 0111 white typewriting or other writing paper is placed nve it iS to be definitely understood, that in a basin or trough containing water and per- We do not desire to limit the application of the 25 mitted to remain in the Water for about five mininvention thereto, and any Change a e utes or until the same becomes thoroughly soaked y he a in the Sequence and du a on o and wet through, so as to produce what is herein- S eps a pe at s, Wit in the Spirit Of the inafter referred to as wet sheet. vention and the scope of the subjoined claims.

This wet sheet is then placed on a glass or Having described the invention what is claimed 30 other suitable smooth and polished surface of as new is!- non-absorbent character, and on this wet sheet A pr of producing invisible Writing n so imposed on the supporting surface, is placed a sheet and restoring such writing to visibility, a dry sheet of paper similar in size and constitus d p oce s mp s ou y wettin id tion to the sheet from which the wet sheet is sheet, then pla the reS111tentWet Sheet on a 35 produced, and in substantial registry with the support g ur ace and on the wet sheet then wet sheet. imposing a dry sheet, then writing on said dry An ordinary lead pencil or other suitable writs eet in a manner to indent Said ing stylus is then taken and used to write in the t e dry g S d We Sheet so as to cause the 4 ordinary way on the dry sheet. When this writwriting to d app and then Wetting e dr d ing is completed, the dry sheet is removed and Wet sheet so as to cause the Writin to pp may be destroyed, since it is then of no further 2. A proce of producing invisible Writing o a use in the process. sheet and restoring such writing to visibility, said The wet sheet indented by the writing is then process comprising thoroughly wetting said 5 taken from the glass supporting surface and sheet, then placing the resultant wet sheet on 5 placed between two pieces of white absorbent a supporting surface and on the wet sheet then cloth, such as ordinary dish towels, so that a imposing a dry sheet, then writing on said dry goodly proportion of the superficial moisture in sheet in a manner to indent said wet sheet, then the wet sheet and on the surface thereof is abdrying said wet sheet so as to cause the writ- 5 sorbed by contact with the absorbent cloths. ing to disappear; and then wetting the dried wet 5 After the wet sheet has been placed as desheet so as to cause the writing to appear, said scribed between the two pieces of absorbent cloth, drying being accomplished by ironing the wet the assembly is placed on a suitable supporting wet sheet between absorbent sheets until said surface and a medium hot sadiron or other equivwet sheet is dry and the Writing thereon has alent ironing instrument is applied to the top disappeared. 55

cloth and the assembly ironed until the moisture JOHN WESLEY MCCULLOCH. in the wet sheet has been dissipated and the CHESTER I-I. MYERS.