US1907816A - Relief engraving - Google Patents

Description

Patented May 9, 1933 i UNITED STATES PATENT OFFICE WALTER HOWEY, 01 NEW YORK, N. Y.

BELIEF ENGRAVING N Drawing. Application filed October 20, 1980. Serial No. 490,105.

My invention relates to improvements in The unremoved portions of the coating are relief engraving, and more especially conthen burnt in by heating the plate, after sists of the features pointed out 1n the claims. vilhich 1t 1s placed in an etchmg bath. In

The purpose of my invention is to pro uce t is bath the uncovered metal is eaten away 5 printing plates of pictorial subjects; that producing hollows or depressions corre 55 ellminates the use of acids as commonly emspondlng to the unltary p1ct0r1al elements ployed in etching engraved plates; that proof the negative. From such an etched plate vides means for translating tone values of subsequent duplicates may be made by relief pictorial subjects into areas having unltary printing in the usual way.

characteristlcs whlch change in accordance 1th my slmplified process I may coat a C3 with the varying pictorial tonalities of the suitablesmooth surface with a layer or film siub]ect;f that mag utlllzetsi,1 directtcontpct In of tgelatiin, lslhegllac, syglthetlg rlesilrll or otther mm or pro ucing e pic or1a um s ma Ellfi w 1c may e ma e 1g sens1 ive without the cooperation of well known camin any desired manner. Upon this sensitized- M era expedients; that instead ofusmg an opsurface. directly in contact with it, place tlcal method 1n the camera which comprlses a so-called half tone negative of the 1ctor1al placing a ruled screen in front of the sensubject and expose it to light whic passes s1t1ve plate any desired form of screen dlthrough the negatlve. The portions acted rectly in contact with the sens1t1ve surface upon by the llght become hard and insoluble.

a may be used; that through the development The parts that have been shaded from the 70 of the exposed SQIISIt IVQ surface there 1s prollght remain soft. These are washed away duced a rellef cons stlng of unltary areas in any suitable solvent so as to leave the revarymg in accordance w1th the llghts and mammg portlons on acommon plane, which shades of the sub ect; and that from such 111 a later step becomes the prlnting surface.

relief surface a reverse 1mpress1on 1s made Wh n dry a paper mat may be impressed from whnah a repllca suitable for rellef pr1nt thereon and a cast made from the mat in the ing is ma e. usual manner ready for relief printing.

With these and ther ends in View, hel e- Or I may coat a transparent sheet of cel- 0 1n descrlbe such instances of adaptatwn 84S luloid, etc, with a similar coating and place w1ll disclose the broad underlylng Ieatllr s a half tone positive against the opposite surof the lnventlon wlthout llmitlng myself to face of the sheet and expose it to light. This the SPec1fic deta11s l'eferFed to will in a similar manner cause the coating to In carrylng y mventlfm I may,use become insoluble where it is acted upon by 3 Whatever alternatwes of m m or y the light. and leave it soluble where the light 85 tence of 1 that i fl varylpg has not penetrated. These soluble portions igi zfiz j z $2 ?tfig s g i fi ggpgfi: are then completely washed away. As soon ing from the broad spirit of the invention. as S 3 lmprisslon h 5. 3

In producing an engraving for relief printa or Sequen pun mt ma 8 m ing inthe ordinary manner a negative is first fi gf g g f material havh a mooth 90 made g a the iublect gj a urfaci i s co i e ed with any of light s en I gig: i g a ggfi g fi g fi Sens: sensitive coating, its surface represents the tivc material which is exposed under thp hallf ate p zil d v Whlch i lf be {i 95 tone De ative Wh th 1i ht ree smooin any eslre manner e ore 1 repasses th rough the'transparent iortions (3f ccives'the imprint of the half tone negative. i1 t -i the t? %1 t t? i ti ift: 32553 ts lifiiisiifi i ia fiffititfi an GIel-IS ro ce e 1c ure ement s of the negative it reriiains 20ft and is coating represents the ultimate printing face. easily removed by warm water or otherwise. Obviously the smoothness of th s face Wlll be retained in the mat and the cast made from it.

As an instance of adaptation, Imay cover any suitable smooth surface with a coating including the following materials \Vax free orange shellac, twenty-nine ounces; water, one gallon; aqua ammonia,

twenty-five ounces. These are broughtto the boiling point which is continued for about twenty minutes or until it reaches the desired consistency when it is allowed to cool before being sensitized. The sensitizer may be one ounce of bichromateof potash dissolved in'forty ounces of water added to the coating solution. It may. stand for an hour before it is used. The coated plate may be I whirled upside down'over moderate heat to hastenthe drying. It is exposed under the negative for about five minutes to the rays of an arc lamp, after which it maybe developed by any desired alcoholic solvent that may include an analine dye such as malachit green. The color brings out the image and. makes the development more certain."

The plate is immersed in the solvent for a minute or two, withdrawn for examination under an amber light. and if needed returned to the developing bath. As soon as the development is completed the plate is washed in cold water. A tuft of cotton maybe used to remove the scum after which the "plate is dried. The portions of the coating which were rendered insoluble now stand in relief.

' ultimate printing face.

an arclamp under a direct contact screen placed between the surface and a pictoral negative of the subject. The unacted areas are removed by means of hot water. An

. alum bath may be usedto harden the coating which remains. Thedepressed portions represent the hollows corresponding to the etched depressions of well known zinc etchings. A mat impression and a metal'cast from it-completes the production'of a relief printing plate. The sensitizer and time of printing may be about the same as in the .pre-

vious adaptation.

When a transparent sheet of celluloid polished on both sides is used instead of i an opaque support or base it is coated onone side with pigmented photographers' gelatin, sen-' sitized inbichromate of potash and exposed 1 through the negative .or positive which is in contact with the other side of the celluloid, similar to the other adaptations. The light,

. as stated, hardens the gelatin opposite the transparent portions of the negative or positive and leaves it soluble everywhere else- This soluble portion is washed away entirely. An alum bath may be used to further harden the remaining gelatin and areversed impression-made. From this a mat may be When a gelatin coating is used it may be sensitized in a 2 per cent solution of bichromate of potash or any cooperating variants of this and exposed to an arc lamp under the time control of an actinometer or otherwise.

' It will be seen that in the use of these expedients all of the many steps inevitably associated with the acid, etching of printing plates are eliminated, and when same'sized reproductions are required the usual camera and screen may be dispensed with by using a replica of any desired screenformation and a film of the subject for direct printing onto the sensitized surface, similar to metzograph screen technique or otherwise. As an alternative, a, transparent sheet. of the required thickness to secure a cooperative screen distance may be placed in contact with the sensitized coating between the film and the screen replica to translate the tones of a'subject into pictorial units which vary in accordance with the lights and shades of a sub- 'ect. J I may in addition to the expedients described use a light sensitive coating of rubber which changes its solubility when-ex; posed to the rays of ultraviolet light pro jected thereon. By using this expedient instead of bichromated gelatine or sensitized shellac I am also able to produce insoluble pictures which comprise fixture elements formed in geometric dots, or lines or irregulargrains by means of half-tone screens of the type described herein, or otherwise. The portions of the coating not acted on by the light are removed by benzene, the same solvent used-in the preparation of the coating.

Such a coating of rubber is vulcanized under the action of ultraviolet light rays. After vulcanization it remains insoluble in its original solvent, but any unvulcanized areas will, however, be removed by the same solvent.

In addition my invention is operable with a new and unique method of makin dot separation screens for use in making direct contact exposures without a camera or the well known four step and flash exposures, common in photoengraving. Such a screen comprises pattern of constant density and variable area, constituting middletone values of variable outline or variable proximity secured by-photoengraving processes, so as to constitute a faithful rendition by photography of the screen pattern that may be imparted in the customary process.

Various types of crosslined screens in use today include the diagonal cross line screen, the sixty degree angle cross line screen, the

. diamond screen. Others include the grain screen and the metzograph screen.

In my use of contact screens which work, without change of stops for highlight, middle tone, and shadow, there is imparted, with contact printing at a single exposure with negative film or positive paper and a suitable positive or negative subject, a constant density dot formation of variable area, shape land separation to conform to that of any of form to the screen dot formation cast y the particular t pe of the above type screens when used in the usual method of process photography, and it consists in using a screen pattern that will conattern of the middletone screen desired when made with the esired type of stop.

For instance the dot formation of a right angled diagonal cross lined screen used with a standard shape half tone stop consists when viewed in a positive print of small, widely separated white round dots in the deep shadows, the dots growing larger and approaching each other in the lighter shadows to the middle tone. point as'alternating square dots touching at the corners at an angle to correspond with the angle of the cross lined screen, and again appearing in the highlights as round black dots decreasing in size and separation toward high light infinity. The use of camera stops of square, round, star pointed or other shapes will impart a distinct character to the dot shape of high light, middle tone and shadow with any screen and these patterns may be multiplied by various combinations of stops and screens. In the use of a screen with a 'pattern to conform to the middletone dot formation cast by light transmitted through any type of screen with any shape of stop desired, I am enabled with contact printing or approximate contact printing to set up a photographic pattern to conform to the dot pattern gamut of the original screen and stop of the process camera from shadow through middle tone to highlight.

This may be done without a camera by "placing a screen of my middletone type in contact or approximate contact with photosensitized paper, film, or plate, 01' sensitized metal orsubstance for engraving, and plaeing a continuous tone negative of a suitable sub'ect in contact or approximate contact wit the screen and simply exposing the three to light so that the light willpass through the negative, the screen and on to the sensitive surface. The order of negative and screen may be reversed without department from the spirit of the invention.

Another manner in. which I use this middletone type of screen, for positive copy, is

There are seen at this place the screen between the copy and a negative film or plate in a proximate contact with the same. This, pre erably is done in a process or copying camera, and is particu arly adapted to the strip film camera, which, when used with an approximate contact cross line diagonal screen, does not give the wide pattern gradation of the wet plate process camera. Another manner in which I use this middletone type of screen is to supplant the retouchingsystem commonly known as veloxing, in the operation of whichit has been the custom to make a positive print from a Wet or dry plate screen negative, sometimes with enlargement, or to make'a proof from an engraved cut, retouching the same in any manner desired by the artist, and then to make a line cut negative fromthe retouched copy and erlggrave the'cut from this line out negative. y my process a positive print may be made with or without camera by ex posing a negative of the subject in approximate contact with m middletone type of screen, and positive printing paper, ready for the retoucher and a line out negative may be made from it after retouching.

A great advantage of the middletone type screen is in connection with the process herein described of using a continuous tone camera negative, the screen, and a plate of any desirable soluble substance or composition. sufiiciently thick to permit of proofing, printing or dry matrix pressing, with which is incorporated a bichromate of ammonium, potassium, sodium, or other light sensitive media having the property' of making a be formed without recourse to process photography, variably timed stops and flashing, burning in, rolling up, powdering, or stage etching with acids and built up resists-11 multiplicity of more than one hundred manual operations which at their highest efiiciency take forty minutes time for four men, photographers, strippers, engravers and routers to accomplish and which, at the high cost, has limited the number of photoengraving plants to less than three hundred newspapers in the United States.

In the carrying out of this process by contact or approximate contact, is meant a screen distance from screen to sensitized plate or film or paper that is less than the screen distance customarily 'used in process camera photography with wet negatives and which is suflicient to rovide-for the rapid formation of correct ighlight, middletone 5 and shadow dots in rapid order with one or 'more exposures through the wide angled pin hole lens openings of extremely short focus that are formed by my middletone process type of screen patterns herein de-' scribed. I am aware that metzograph conthat films of a composition and nature such as bichromated glue and gelatinhave been used in collotype and offset.

Such processes are n no way akin to my invention which provides for a light sensitized surface for relief halftone dot impressions of sufiicientthickness to permit of dry matrix pressing with all the characteristics of a half tone engraving of copper or zinc, except that the engraving is doneby a solvent instead of an acid, and which is printing.

of sufficient stren th and toughness to withstand the require pressure customary in dry matrix pressing and to withstand the friction and pressure of direct high speed press" WhatI claim is: v 1. The process of producing a replica of a screen interpreted pictorial sub ect for relief the screen, in 7 close I pr y to each printing, which consists in coating atraiis parent support with a sensitive material capable of being insolubilized under the action of light, in subjecting the coating to a source of light-through a-transparency havingvariable sized opaque and inverse transparent areas whose characteristics vary in accordance with the hghtsfand shades of J Contact with Such Surface in p g a p a pictorial subject" said transparency being in .contact with the, transparent support whereby the areas of the coating oppositethe' transparent areasbecoine hardened, and the soluble, in removing the unhardened portions by means of a suitable'solvent applied to the face of the coating, in'drying the remaining portions, in taking an' impression therefrom, and in subsequently translating the impression into a printing plate.

2. A direct engraving process which eliminates the well known acid etchin of metallic plates, consisting in coating a ase with the subject onto the light sensitive material sult, in taking animpression from it, and in subsequently translating it into a printing plate.

3. The process of producing a replica of a pictorial subject for relief printing, which consists in making a composition plate consisting of a soluble coating and a light sensi tive agent, in exposing the saineto a source of light through a transpare ghaving variable sized opaque 'area" "characteristics vary in accordance with the lights and shades of a pictorial subject to selectively harden portions of the plate, in removing the unhardened portions by meansof a suitable solvent to a depth sufficient to permit of relief half tone printing or dry matrix pressin ing a pictorial subject between the light and the sensitized plate injclose relation to both, and in developing the image.

5. A direct-engravingprocess, which con-,

4. A direct relief engraving process w ich sists in utilizing a screen having isolated areas of middle tone characteristics secured by ordinary screen. separation, in coating a suitable surface with asensitive material capable of being insolubilized under the action of light, in subjecting the surface to a source of light projected through a pictorial subject other and in developing the exposed surface.

6. A direct engraving process which consists in forming a middle tone screen by ,ordinary screen separation ina camera, in

coating a suitable surface with a sensitive material-insolubilized under the action of light, in placing the screen in approximate and the screen onto the sensitive surface, and

areas opposite the "opaque area's remain; In developing the image's) m d- '7. An engraving process which consists, in pro ectlng a pictorial subject through a screen having isolated middle tone character istics, in placing a sensitive surface capable light in close contact with the screen adapted to receive the projected image, and in subse-' quently developing'the image.

In testimony whereof I aflix my signature.

WALTER HQWEY.

to form raised and depressed portions by development in a solvent, in drying the re- 1 of being insolubilized under the action of