US2127944A - Process for reproducing images - Google Patents

Description

Patented Aug. 23, 1938 UNITED STATES PATENT OFFICE PROCESS FOR BEPBODUCING IMAGES No Drawing. Application June 13, 1936, Serial Pie. 85,053

3Claima.

This invention relates to a novel and improved method of faithfully reproducing images upon solid surfaces. More particularly, it relates to a process for reproducing a decorative finish upon a hard, plane surface, such, for example, as a sheet metal panel.

Heretofore, the process most satisfactory and most successful from a commercial standpoint for reproducing images upon plane surfaces has embodied substantially the features disclosed in U. 8. Patent No. 1,548,465 to Henry. In accordance with the teachings of this patent, which is primarily directed to the reproduction of wood grain on sheet metal panels, a suitable section of wood is photographed in the usual manner to produce a negative photographic plate. Subsequently, a photographic positive is produced from this plate and a printing plate or roll is reproduced from the positive in accordance with practice well known in the photcgravure art. Preferably, the printing plate thus reproduced is formed by means of the well known Rembrandt screen in order that the resultant product will have in its surface a plurality of recesses of varying magnitude. The plate is coated with a stain and a doctor blade or wiper is utilized for the purpose of removing surplus stain from the surface of the plate. When a soft roll is passed over the plate the masses of pigment or stain within the recesses will be picked up on the roll and will be transferred to the surface upon which it is desired to reproduce the image photographed. This process results in the small individual masses of pigment being merged and all lines of union between the masses obliterated in order that a more detailed reproduction and a more uniform and attractive finish will be obtained.

The present invention contemplates the provision of a process which obtains greatly improved results and which results in a reproduction more faithful in detail than any heretofore obtainable. Further, it will be appreciated that the process of the present invention is considerably simpler than the Henry process outlined above and that the unnecessary and undesirable steps forming an essential part of the Henry process have been eliminated.

While it will be appreciated from the following detailed description that the process forming the basis of the present invention is primarily directed to a method of reproducing a finish in imitation of natural wood greining upon a sheet metal panel, the generic inventive concept presented herein is of much broader scope. It will be readily apparent that certain features of the present invention and steps of the method outlined herein will iind great practical utility in any process wherein it is desired to reproduce upon a plane, hard or solid surface an image of anything capable of being photographed.

In order that a full and complete understanding of the present invention may be obtained, the specific process outlined below is directed to the reproduction of an imitation wood grain finish on a sheet metal panel. The process may successfully be practiced in the following manner.

A photographic plate is first exposed to white light of uniform intensity and ordinary charactor for a period of relatively short duration, the period, however, being sumciently long so that in the event the plate were developed, the resultant product would be relatively dark and of uniform density throughout its entire surface. The particular length of this initial exposure depends upon many variable factors, for example, the particular type of photographic emulsion used on the plate, the nature and intensity of the source of white light to which it is exposed, and the length of such exposure.

By way of illustration, the following initial exposure has been found particularly satisfactory and in the practice of the method of the present invention when conventional photographic plates now commercially obtainable are used. The plate is exposed for approximately two seconds to a 25-watt Opal tungsten lamp at a distance of eight feet. This plate is not developed after this initial exposure, but is subjected to a desensitizing process which materially reduces the speed or light SBHSIUVEHESLL of the emulsion which covers the plate. While many and various methods may be utilized to obtain the necessary densltization of the exposed plate, the following process has been ,found particularly satisfactory for accomplishing this purpose. The plate is preferably desensitized by bathing it for three minutes in a desensitizing solution which preferably is composed of:

The plate is preferably swabbed with cotton so that the wetting action of the solution will be uniformly distributed over the entire surface of the plate. and while wet the plate is placed in a plate holder of a camera.

A section of wood has the surface thereof finished and prepared in a manner to bring out not only the grain of the wood in detail, but the highlights and other ornamental effects thereof. A particuiariy satisfactory manner of accomplishing this is to utilize a filler of Chinese blue or Milori blue which may be worked into the surface of the wood in order to accentuate the ornamental appearance thereof.

While the particular manner in which the wood is photographed may be varied within relatively wide limits, depending upon the specific type of equipment used, it has been found particularly satisfactory to use a camera having a diaphragm opening of F22 and provided with a red color filter, preferably such as is known as a "Wrattan A 25 red" filter. The camera is focused on the sectin of wood which has been prepared as described above for a period of approximately forty minutes with strong illumination. Manifestly, the length of the exposure is directly dependent upon the illumination and consequently the length of this exposure may be varied within relatively wide limits. While various types of cameras may be satisfactorily used for the purpose, it has been found particularly satisfactory to use a camera provided with an eighteen inch process lens and dispose the slab of prepared wood about thirty-six inches away.

After exposure, the plate is developed in the usual manner, then fixed, washed and dried, and the resulting product provides a positive image of the section of wood photographed, and it has been found that the image upon the plate is particu larly clear, accurate and detailed. Further, it has been found that the minute features of the grain, the highlights and other factors which contribute to the ornamental appearance of finished wood, are faithfully reproduced in detail.

After completion of the preparation of the plate in accordance -with the method outlined above, any suitable process may be utilized for the purpose of providing a printing roll or plate to be utilized for transferring the image thus formed to solid surfaces. While any suitable process such as a half tone may be used for producing the printing plate or roll from the positive plate, it has been found preferable as will hereinafter be more clearly seen to utilize a photogravure process, such for example as .he following:

A print may be made from the plate on sensitized photo carbon tissue such as is ordinarily employed in the intaglio process of printing. After exposure in making the print on the carbon tissue, the latter is again exposed to light. through a screen of the Rembrandt type in order to break up the surface of the image into a plurality of individually isolated elements or bodies. This image is then etched upon a metallic plate in the conventional manner and the individual bodies making up the image will be reproduced as recesses of a magnitude varying in accordance with the darkness of the original plate for which the metallic reproduction plate was prepared.

' When paint, stain or pigment is applied to the metallic reproduction plate, the recesses will be filled and the surplus pigment may be wiped 0d. The pigment disposed in these recesses may be transferred to the surface upon which it is desired to reproduce the image by means of a soft resilient roll, which serves to merge the individual masses of pigment and consequently obliterate all lines of union therebetween. providing. a faithful reproduction of the image photographed.

While t has long been well recognized that exposure of a plate to light will give a negative with certain emulsions, it has been found that upon further exposure a positive will result. These regression phenomena are not fully understood. What is known as the Herschel effect is 'an even morepronounced regression phenomenon than the above, and it is this latter effect which contributes materially to the present invention.

It has been found that if a photographic plate is initially exposed to a source of light and subsequently exposed to light of predominantly longer wave length, this second exposure tends to act in a way which serves to restore the emulsion substantially to its original condition prior to initial exposure. As a result of experiments it has been pretty definitely ascertained that this bleaching eflect is considerably more pronounced if the diflerence in wave length between the two exposures is relatively great. Consequently, it may be appreciated that in the event that the wave length of the light used for the initial exposure is sufficiently short the subsequent exposure may be made with ordinary light, and the necessary regression phenomena will still be present.

It will be apparent from the foregoing that the plate, after its initial exposure. if developed in the conventional manner, would be uniformly dark throughout its entire surface. The process of photographing the desired image through a red filter serves to exercise a bleaching effect upon those particular portions of the plate upon which the most light is projected, consequently resulting in the direct production of agpositive Plate as a result of the photographing The particular dyes or pigmented materials utilized for accentuating the grain of the wood should be of such a color that they will not serve to reflect any appreciable amount of light upon the plate during the photographing process. The reason that Chinese or Milori blues are chosen for use in the foregoing specific illustration of the process is that these two have been found to be notably lacking in any red components and are hence extremely satisfactory when a red filter is used.

It has been found that the image reproduced by the above donned process is, as has been pointed out, particularly faithful in detail. When the specific process is utilized for the reproduction of wood graining on metallic surfaces,as has been described above, the process results in the clear and faithful reproduction of not only the grain structure but the high lights of the wood grain, which features greatly improve the appearance of the resultantproduct.

It will be appreciated that the process outlined above may be conveniently utilized for the pur-.

pose of photographically reproducing almost any type of image upon a plane, solid surface and that the inventive concept is not limited to the specific process of reproducing wood graining as outlined.

Many other and further modifications of the process outlined herein. falling within the scope of the invention as defined in the subjoined claims, will be clearly apparentto those skilled in the art.

I claim as my invention:

1. Themethod of reproducing wood graining upon a solid surface which comprises preparing a .wood panel to accentuate the grain thereof. initially exposing a photographic plate to a source of white light of uniform intensity, partially desensitizing said exposed plate, phoiographlni said prepared wood panel through a color filter on said plate to produce a positive reproduction oi the grain oi the wood thereon, said color filter serving to exclude light of short wave length and subsequently utilizing a photogravure process for reproducing the image from said plate upon a solid surface.

2. The process of reproducing wood graining upon a solid surface which comprises initially exposing a photographic plate to a source of white light, subsequently partially desensitizlng said exposed plate, preparing a wood panel with blue dye to accentuate the grain thereof, photographing said prepared wood panel on said exposed partially desensitized plate through a color filter to produce thereon a positive image of the food grainlng in said panel, said color filter being of the type which serves to excludes light of light, developing said plate, preparing a photogravure plate from said plate, and transferring the image from said photogravure plate to a solid surface by a photogravure process.

ROBERT R. TANNER.

CERTIFICATE OF CORRECTION.

Patent No. 2,l2"( ,9l. l

August 25, 1958.

ROBERT R TAN'NER it is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, first column, line 17, claim 2, for the word "food" read wood; and line 18, for "excludes" read exclude; and that the said Letters Patent shouldbe read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 11th day of October, A. D. 1958.

(Seal) Henry Van Aradale Acting comrhissioner of Patents.

said prepared wood panel through a color filter on said plate to produce a positive reproduction oi the grain oi the wood thereon, said color filter serving to exclude light of short wave length and subsequently utilizing a photogravure process for reproducing the image from said plate upon a solid surface.

2. The process of reproducing wood graining upon a solid surface which comprises initially exposing a photographic plate to a source of white light, subsequently partially desensitizlng said exposed plate, preparing a wood panel with blue dye to accentuate the grain thereof, photographing said prepared wood panel on said exposed partially desensitized plate through a color filter to produce thereon a positive image of the food grainlng in said panel, said color filter being of the type which serves to excludes light of light, developing said plate, preparing a photogravure plate from said plate, and transferring the image from said photogravure plate to a solid surface by a photogravure process.

ROBERT R. TANNER.

CERTIFICATE OF CORRECTION.

Patent No. 2,l2"( ,9l. l

August 25, 1958.

ROBERT R TAN'NER it is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, first column, line 17, claim 2, for the word "food" read wood; and line 18, for "excludes" read exclude; and that the said Letters Patent shouldbe read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 11th day of October, A. D. 1958.

(Seal) Henry Van Aradale Acting comrhissioner of Patents.