US1502482A - Dull or roughened photographic film and process of making same - Google Patents

Description

Patented July 22, I924.

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RUDOLF OERTEL, OF LICHTERFELDE, NEAR BERLIN, AND FRIEDRICH DREYER, OF ZEHLENDORF, NEAR BERLIN, GERMANY, ASSIGNORS TO THE FIRM GOERZ PHOTOCHEMISCHE WERKE G. M. B. H., OF ZEHLENDORF, NEAR IBERIJ'N, GERMAKTY.

DULL 0R ROUGHENED PHOTOGRAPHIC FILM AND PROCESS OF MAKING- SAME.

No Drawing.

To all whom it may concern:

Be it known that we, Dr. RUDoLF OERTEL, chemist, a citizen of the German Republic, and resident of Lichterfelde, near Berlin, Germany, and FRIEDRICH DREYER, superintendent, a citizen of the German Republic, and resident of Zehlendorf, near Berlin, Germany, have invented certain new and useful Improvements in Dull or Roughened Photographic Films and Processes of Making Same (for which we have filed application in Germany March 3rd, 1923) of which the following is a specification. p

This invention broadly refers to the manufacture of dulled or roughened photographic films such as used for the production of moving pictures and for similar purposes, and it is intended to devise new and improved means for the production of such films and to generally improve and perfect the copying of films and of the pictures provided thereon.

In the procedure of copying photographic films for cinematographic purposes there is the drawback that after the taking of but a small number of copies very objectionable scratching of the negatives is produced which greatly interferes with the quality of the copies, and in consequencethereof the positive films, when projected, exhibit the inconvenience of cloudin or raining phenomena. The same draw ack occurs likewise with increasing scratching (f an originally unobjectionable positive Attempts have already been made towards avoiding these inconveniences by submitting the films, both positive as well as negative films, to a dulling or roughening process; however, the ordinary .methods of dulling or roughening by the employment .of a sand blast or by grinding fail to produce satisfactory results.

Now, in accordance with this invention the object of a dulling or roughening of the surface intended to dispense with the inconvenience of the clouding or raining of the projected picture is accomplished by submitting the surface to be treated to the application of a spray of a dusting of varnish, japan or the like. This procedure may be effected by spraying the surface with a suitable transparent varnish, lacquer, japan or the like by means of a varnish Application filed December 26, 1923. Serial No. 682,827. l

' sprayer or injector, provision being preferably madeby' a corresponding selection of the nozzle section and of the pressure of the atomizing stream of compressed air, as well as by adjustment of the concentration of the solution, to sov regulate the size of the particles of varnish and the like that the desired fineness of grain for the dulling or roughening effect is obtained. The dullmg or roughening produced in this mannor is of such a degree of fineness that it .even affords the possibility of covering up begins to appear upon the copies. In certain cases it may also be of advantage to dull the crude negative film or the sheet of foil intended for the manufacture thereof, and particularly, where the film is intended for the production of very delicate negatives. It is also advisable to dull films with delicate negatives before beginning to copy,

that is to say, before the occurrence of scratches, because the action of the light in the luminous portions of the negative is thereby decreased. 1

The dulling or roughening is also of advantage in the case of positive films in case they exhibit such a degree of scratching that the projected pictures show the well known phenomenon of clouding" or raining.

As a material for the lacquer or varnish to be sprayed a solution'of a cellulose compound may preferably be used, such as for instance a solution of about one per cent (1%) nitro-cell'ulose in ether-alcohol 1:1 which solution is sprayed by means of a varnish sprayer or injector the nozzle aperture of which is about a tenth millimeter,

coloring the film by adding a suitable pigment to the trans arent lacquer or the like. It is generally a visable to make an addition to the lacquer or varnish of a metal salt soluble therein, of calcium chloride for example, in an amount of about one per cent of the percentage of nitro-cellulose in the solution.

The invention has been described herein in its broad aspects, and it should be understood that it is not limited to the particular substances and means of procedure ashereinbefore stated merely for the purpose of explanation but it is susceptible of modifications and variations to suit existing conditions and the convenience of the operator and without deviating from the spirit of the invention as pointed out in the claims.

What we claim is 1. The process of dulling photographic sheets, which consists in treating the surface thereof with a spray of a varnishing composition..

2;The process of dulling photographic picture sheets, which consists in dusting the surface thereof with a solution of a cellulose derivative.

3. The process of dulling photographic picture sheets, which consists in spraying the surface thereof with a mixture of a var nishing composition with a metal salt soluble therein.

4. The process of dulling photographic picture sheets, which consists in spraying the surface thereof with a solution of nitrocellulose in ether alcohol averaging about one per cent of the substance.

5. The process of dulling photographic picture sheets, which consists in making a mixture of nitro-cellulose with a small amount of chloride of calcium, treating said mixture with ether alcohol and spraying said mixture upon the surface to be treated.

6. The process of dulling photographic picture sheets, which consists in mixing nitro-cellulose with about one per cent of chloride of calcium, mixing about one per cent of said mixture with equal quantities of ether and alcohol, and dusting said mixture upon the surface to be treated.

7. As a new article of manufacture a photographic picture sheet carrying a dull coating consisting of finely subdivided transparent varnishing composition.

8. As a new article of manufacture a photographic picture sheet, carrying a dull coating of most finely'divided grains of a cellulose compound.

9. As a new article of manufacture a photographic picture sheet, carrying a dull, most finely grained coating of a mixture of a cellulose compound with a metal salt soluble in such compound.

10. As a new article of manufacture a photographic picture sheet carrying a dull, most finely grained coating of a mixture of a cellulose compound with approximately about one per cent of chloride of calcium.

In testimony whereof we have signed this specification in the presence of a subscribe ing witness. v

DR. RUDOLF OERTEL. FRIEDRIOH DREYER. Witness:

E. HOLZERMAN.