US2130735A - Method of producing a printing plate - Google Patents

Method of producing a printing plate Download PDF

Info

Publication number
US2130735A
US2130735A US126933A US12693337A US2130735A US 2130735 A US2130735 A US 2130735A US 126933 A US126933 A US 126933A US 12693337 A US12693337 A US 12693337A US 2130735 A US2130735 A US 2130735A
Authority
US
United States
Prior art keywords
layer
screen
printing
plate
silver
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US126933A
Other languages
English (en)
Inventor
Eckardt Emil Eduard
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to BE394468D priority Critical patent/BE394468A/xx
Priority to DEE43807D priority patent/DE665893C/de
Priority to FR751051D priority patent/FR751051A/fr
Priority to DK51780D priority patent/DK51780C/da
Priority to GB5072/33A priority patent/GB415399A/en
Priority claimed from US698671A external-priority patent/US2071821A/en
Application filed by Individual filed Critical Individual
Priority to US126933A priority patent/US2130735A/en
Application granted granted Critical
Publication of US2130735A publication Critical patent/US2130735A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F5/00—Screening processes; Screens therefor

Definitions

  • This invention relates to photographic image My invention permits making negative or posibearers, such as plates or films, and to a method tive photographic pictures of any desiredv subof making and reproducing same, such as dejects (persons, articles, scenery, etc.) embodying scribed in my application, Serial No. 698,671, filed the natural screen referred to. From the originals November 18, 1933, of which application this is a copies such as image reproductions, printed re- 5 division.- productions or the like can be produced by any It is an object of my invention to prepare a well known methods of reproduction and printphotographic image bearer so as to facilitate its ing. reproduction and reduce its cost.
  • the silver image (and the printing faces of the plates obtained
  • the darkerportions obviously contain more such particles than the lighter ones, and the lightest portions may even befree from all silver parti- I cles, that is to say, they may b pure white or fromthe image) is selectively influenced and absolutely transparent.
  • the screen may not F t g from the 3 of h silvershow in those portions of the image which are hahde layer n during the Individual stages of absolutely black or pure white, but only in the the method so a desired effect of the shadings or half tones which are intermediate productions is obtainedthese extremes; a 1
  • the exposure may be so regulated that the lat- The efie t of photographs and particularly ent image obtained is most favorable for the 50 portraits, becomes more artistic by the natural 91 in VleW,v
  • the p ent Of the latent screen so that reproductions from such photoimage must be pe n ed such a manner that graphs, plates orfilms are not only more conthe blackened silver particles which are avail.- trasted than those obtained by the bid method, ble after the xp u are P p ly produced but bear a great resemblanceto engraving s. j and distributed The same applies to the fixing,
  • the result is a dislocation and rearrangement of the blackened silver particles whereby the particles are crowded nearer together in certain places while being withdrawn from the regions in the vicinity of the points of local concentration. In this way the natural screen is formed.
  • the blackened silver particles combine into curved lines or individual spots of black, which are bordered or surrounded by curves or areas of white.v
  • Fig. 1 shows a screen with black curved lines
  • Fig. 2. shows a screen with black spots, both figures being magnified. 4
  • Fig. .3 is a magnified cross-section of an image bearer having two intermediate layers between the halide layer and the support of the layer, as will be described more in detail below.
  • I, I in Fig. 1 indicate the black curves or lines formed by the silver particles, with corresponding white liens or areas surrounding them, while 2, 2 in Fig. 2 indicate the black spots of silver particles described above.
  • the plates were uniformly exposed to light for a short time.
  • the dislocation and. re-arrangement of the silver particles and the variation or subdivision of the silver image produce a very plastic effect in negatives, positive copies, and lantern slides.
  • the irregularity of the lines or spots of dislocated sil- .ver particles, with their skeleton-like subdivision, produces an artistic effect resembling that of an engraving, without in any way interfering with the outlines and the effect of the. picture.
  • cording to this invention is equivalent to the effect of a high-class'screen.
  • screen as obviously eliminated.
  • the photographic shade is formed exclusively by a rearrangement of the silver particles present in the layer.
  • the formation of the natural screen in the silver-halide layer comprises two stages:' the developing of an exposed layer and the softening or soaking of the-layen-to impart to it a jellylike character which permits the blackened silver particles to move or "float in the layer.
  • the silver particles have a tendency to cluster as soon as they are free to move or fioat in the softened or soaked layer, and this tendency can be furthered by physical, thermal or chemical action mersed. The higher the temperature gradients,
  • Such alternating baths may be applied before the development, be-
  • the developer and the fixing bath themselves may form parts of an alternating bath, 1. e., the developer or the fixing bath may be hot or cold, and the preceding or succeeding bath may be cold .or hot. It has proved favorable in certain cases to first place the layer in water or oil of about 25 C. before developing the layer, or to first subject the layer to the action of water vapor (steam).
  • the finest screens are obtained by thermal action, the layer being heated in dry condition to about 50 (3., or more, before being developed, so that its water content is partly or completely expelled.
  • a layer which has been subjected to this preliminarydrying treatment will stand baths, and more particularly developers, of rather high temperature, up to 50 C. and even above this temperature.
  • Plates or films may be subjected to the preliminary drying treatment before being sold. Such plates or films, in addition to their other desirable properties, will stand tropical temperatures as they will hardly be exposed to temperatures of 50? C. and more even in the Tropics.
  • the layer is slightly contacted with the water in the bath repeatedly, say, six to ten times, until the layer has become mat like velvet.
  • a similar operation may be performed in the screenforming bath, but only before the screenhas' if a warm developer is followed by a cold bathof ammonia, ether, or a mixture of both. In a screen obtained by such chemical treatment, the
  • thefdensity and blackness of the curves i or spots 2 are uniform because the plates were exposed to light without a picture being projected thereon.
  • the formation of the screen was prematurely interrupted.
  • the curves or lines in Fig. 1 are all connected but subjected to .a continuous change of direction.
  • the simplest method of producing a natural screen is the following:
  • An exposed and developed layer is placed in a bath of water having a temperature of say to 36 C. and left therein for ashort time, say one or two minutes, until the silver particles have clustered.
  • a bath of oil such as olive oil, sun flower oil or the like may be used, or the layer may be subjected-to the action of water vapor.
  • a plate or film which has been treated according to this simple method may serve for use as a lantern slide, or for photo copies and prints on paper, but as a rule the screen is' not yet satisfactory. It is not sumciently contrasted because the silver particles have not yet all clustered in the dark portions, so that the dark portions are not altogether black and the white portions are not pure white,
  • the screen is coarse because, if proceeding as described, the clustering of the silver particles occurs very slowly so that the individual clusters are toolarge and not broken up as finely as rethe intermediate areas become more transparent and of reducing the width of the lines until the natural screen becomes as fine as the usual artificial screen.
  • the treatments'at the same time improve the clustering and reduce the width of the lines. It is important that the lines should be altogether black and the intermediate areas altogether transparent because, if this condition is fulfilled, the printing plates obtained.
  • the screen may be improved by single or alternating baths with or without chemicals, heating .of:-'the1ayer before.
  • the-"formation of the natural screen is favored by a previous ageing of the developer, i. e., allowing it to stand-for along time, or heating it to the boiling point, or mixing a developer which has been thus heated, with some unheated developer.
  • the devel-' oper is heated to the boiling point in a dish of enamelled steel which is held at'an angle above a spirit or gas flame, the residual developer adher ing to the raised portion of the dish being evaporated to dryness and the boiling developer washing over the dry portion and absorbing the dried developer.
  • the developer is now cooled and used at a temperatureof about22 to 26 C. This; treatment yields very clearly defined screens of" any desired fineness.
  • This invention further provides for the appli cation of salts and salt preparations to the fixing salt.
  • salts may be sodium chlorideor ammonium chloride.
  • ammonium chloride For instance, one part of ammonium. ehloridemay be mixed with four parts of sodium hyposulphite and twenty parts of water. Treatment with such salts favors and accelerates, the, subsequent formation of the screen, and prints taken from the plates or films thus treated are more harmonious and possess a more impressiveart-printing effect.
  • This subsequent treatment is not exactly the same as the usual intensification or reduction of a normal photographic image in which the silverparticles do not cluster to forms black and opaque lines or spots, with white and transparent areas surrounding them, as described, but are distributed more or less uniformly and are involved as uniformly in the intensification or reduction.
  • the subsequent treatment according to the invention renders the black portions more opaque, and the transparent ones more a transparent.
  • This treatment not only renders theintermediate areas more transparent but also hardens .the layer for the repeated application of screenforming baths for refining the screen.
  • the layer may also be treatedfor a short period with a mercury or other intensifier.
  • a mercury or other intensifier I prefer the treatment with the solution of potassium ferrocyanide above described, and with a mercury.
  • composition of-this bath may intensifier, it a solution of grams of r'nercuric. chloride in 100 grams of water.
  • a uranium intensifier may be preferable-to themercury intensifier.
  • a suitable uranium intensifier may be prepared as vfollows:
  • Solution Il 500 ccms. of water, 5 grams of potassium vferrlcyanide' and 25 ccms. of glacial acetic acid', v I ..-.-;-Equal volumes of. the two solutions are mixed. Becausaof the uniform distribution of the silvenparticles in the layer of the plate, the
  • i uranium intensifier as a rule 'reddens all parts of a normalplate, but in a plate having a natural screen it only reddens the dark portions where the silver particles. have clustered, because the whitev portions are almost free from. silver particles. all chromates are highly sensitive metal printing plates holds not only spots which are deep black but also spots which are only grey and otherwise could not be etched on account of insumcient blackening.
  • a plate is dried in hot air at a temperature which is as high as possible without damaging the layer, say 50 C. ormore.
  • the plate may be dried before or after the exposure.
  • the period of exposure is reduced to about one half of the normal period. If the operator knows what kind of reproduction is required, he will consider this in the exposure. Thus the exposure should be to red and yellow, the chromate layer on the' shorter for reproduction in the manner of line etching than for half-tone reproduction.
  • the plate is now developed with a rapid developer, such as those sold under the trade-names of Edinol, Metol, Rodinal or the like. 'If Rodinal is used, the solution should contain 5 to parts of Thiabath isstollowedby a coldswater bath having" a temperature of 8 to 10 C., the two baths bei applied alternately.
  • the plate may now be treated with a bath of 5 grams of potassium ferrocyanide in 100 ccms. of water, which is mixed with 10 parts of a'fixing bath containing 25 grams of sodium thiosulfate in 500 ccms. of water.
  • the plate may also be treated with a solution of 10 grams of mercury chloride in 500 ccms. of water and with a solution of 10 grams of potassium bromide in 500 ccms. of water.
  • the baths may also be applied in reversed sequence.
  • the plate is not dried but is developed at room temperature in a developer containing 7.5 to 30 parts of Rodinal developer in 100 parts of water. The developing period should be as short as possible, say one to three minutes.
  • the fixing bath contains 20 grams of sodium thiosulfate and 10 grams of ammonium chloride in 100 ccms. of water.
  • the screen-forming bath is now applied, being a'hot-water bath of 28 to 44 C., whereupon the plate is placed for a short time in a solution of 10 grams of mercury chloride and 5 grams of sodium thiosulfate in 100 ccms. of water. The plate is now washed in cold water and, if required,
  • the plate remains in the intensifier, which is agitated, for about three minutes and is then blackened by means of highly concentrated, say a ammonia solution at a temperature not exceeding 35 C., or by'means of a solution of 5 grams of sodium thiosuli'ate in 100 ccms. of water.
  • reproduction plates photomechanical or phototechnical plates which have a very thin layer and low light-sensitivity require special treatment.
  • the original negative or positive pictures are photographed on such plates.
  • the plate is apparently black throughout. Howfor instance at 22 C. After fixation, a hot-water is applied which is contacted with. the plate from six to ten times in the manner described above.
  • the fixing bath is preferably prepared with a rapid fixing solution containing for instance 20 to 40 grams of sodium thiosulfate and 5 grams of ammonium chloride in 100 grams of water, and the fixing bath is applied in warm condition has been found that the temperature of the bath should be between and 31 C. and on no account above 32 C.
  • the water in the hot bath is contacted with the plate two or three times as described, but only before the screen has formed and until the layer has become mat like velvet.
  • the duration of the application ofthe hot-water bath is 10 to 20 seconds and it is followed by a cold-water bath. which is applied until the layer has cooled down to the temperature. of the bath.
  • Its duration may for instance be five seconds.
  • the treatment with the alternating baths is continued until the screen is black throughout the intermediate areas being altogether transparent,
  • the plate for one or two seconds is placed in a strong solution of. potassium ferrocyanide, containing for instance 10 to 15 grams of ferro-cyanide and 4 grams of thiosulfate per 100 ccms. of water.
  • the reduced plate is placed in a cold-water bath, and this treatment is repated as often as required.
  • Old and dry plates may also be subjected to the treatment for forming a screen therein. If
  • this screen becomes finer by the repeated breaking-up of this structure.
  • Old plates, developed plates, fixed and dry plates are placed in water of about 25 C., preferably after having been previously heated to about C., as described.
  • the raised portions of the etched printing plates are protected fromthe attack of the etching liquid by a coating, in order to obtain more plastic reproductions.
  • the natural screening according to this invention permits a more simple and more efficient operation by applying to the screened layer itself black color with a colored pencil. In this manner the plate can be retouched by means of black lines and areas, while in the autotypes produced with separate screensv the covering could only be altered in spots.
  • etching may be extended much more-deeply than was heretofore possible even with repeated etching, for instance with strong acid such as is used for line etching.
  • a suitable acid may contain 15 ccms. of concentrated nitric acid in 100 ccms.'o f water.
  • the contrasts may be so strong that upon etching the highest lights or the lighter shades disappear altogether. The highest lights are the finest metal 'cones which remain behind. If they breakdown, this only increases the plastic effect of the reproduction, as it occurs only in the lightest portions of the picture. In this manner, the original is reproduced with all its shades, or the reproduction obtained is modified, until its effect is substantially equal to that of a line etching made by hand. This variety of reproductionsmay be made selectively from one original.
  • the exposure should be shorter than normal so that the latent silver image becomes rich in contrasts, with the half tones comparatively undeveloped and the contours of the image standing out distinctly. For the same reason the developing period should be shortened.
  • the screen in the negative must not show in these portions of the copy or print which are either absolutely black or pure white but only in the intermediate shadings or half tones. The lightest portions of the copy or print which correspond to the absolutely black portions of the negative,
  • contours of the image remain as the printing .surface. This may be effected, for instance, by-
  • the operator should perform the treatment so as to obtain a less strong contrast, 1. e., the sensitive layer should be overexposed and developed for a longer period, the formation of the screen should be more effective, and the etching less intense.
  • reproductions or prints from etched metal plates which have been obtained from an original with a natural screen can thus be made more artistic and more similar to engravings, but above all with more intense contrasts.
  • normal printing paper of various kinds can be printed with such plates, but also other materials.
  • a particular improvement achieved by this invention is the possibility of directly printing photographic layers. This has already been attempta hardener.
  • the new method which brings forth the natural screen is superior tothe old methods not only in the printing with electrotypes and in book printing, but also in plain, offset, copper-plate and phototype printing.
  • all that is required is to make a lantern-slide copy from a negative provided with the natural screen without the formation of the screen being repeated in the lantem'-slide copy.
  • the screened originals may be plates or films, and they may be photographed on plates or films, as desired.
  • the new method is also particularly important for the printing of bank notes and photostat copies of documents or the like.
  • the new method provides an infallible means for ascertaining whether a bank note is genuine, i. e., whether itwas made from the original and from the type of a given series. Not only the arrangement and clustering of the silver particles will never repeat itself, but it is also very difficult to exactly-imitate the etching as it is found in a given plate.
  • the new method may be applied to letter-press as well as to copper-plate printing.
  • letterpress printing more copies are obtained from a given type than in copper-plate printing which was heretofore exclusively applied to the printing of bank-notes, because letter-press. printing requires much higher pressure than copper-plate printing, so that the life of the type is shortened.
  • the formation of the screen and/or the etching may be so performed that the characteristic features of the screen are visible to the naked eye on the reproduction.
  • This invention further relates to the image.
  • bearer itself or to its silver-halide layer; the silver-halide layer must be selected in conformity with the desired character of the natural screen.
  • the layer should be harder for reproduction by printing, and softer for photographs. On the one hand, it must readily be transformed into the jelly-like condition required for facilitating the movement and the'clustering of the silver particles, while on the other hand it must'not meltcompletely. It has already been mentioned above that the silver particles should float in the layer.
  • the silver-halide layer is made of soft gelatine or mixed with a small percentage of Such hardeners are dispersed substances which solidify the gelatine, for instance starch, chalk and the like.
  • the hardener should be made of a material which is as transparent as possible, or, in the case of a material which is not light-permeable, such as chalk, it should be dispersed so finely as not to interfere with the transparency of the layer;
  • a suitable hardener may conteain equal parts of gelatine and starch, for instance rice starch.
  • the object of the hardener is to enable the layer to stand a hot-water bath of the temperatures indicated above without being dissolved, while on the other hand the layer must not be rendered so consistent by the action of the hardener that it interferes to any appreciable extent with the free movement of the particles.
  • Soft gelatine is preferable not only because it facilitates the free movement of the silver particles, as described, but also because-it will assume the jelly-like condition permitting the formation of the screen at low temperature. Therefore, with, a layer of soft gelatine, the screen-forming baths may be comparatively cool and the proper temperature of the bath is more easily ascertained.
  • the layer may be dried by being heated to about 50 C. before being developed, in order to partly or completely expel its water, and that plates may be marketed for the Tropicsin dried condition. This feature is of general importance.
  • Such strata or intermediate layers may also be inserted between the layer carrying the screen and its support, i. e., the glass backing of a plate, or the Celluloid backing of a film.
  • the plate or film shown in Fig. 3 has two intermediate layers, 3 being the glass or Celluloid backing, as the case may be, 4 being the layer in which the screen is formed, and 5 and 6 being two intermediate layers which are interposed between the screen layer and the backing 3.
  • intermediate layers or strata may obviously be provided.
  • the principal object of the intermediate layer or layers is to provide a resilient support for the developed silver-halide layer 4, since the intermediate layer remains resilient notwithstanding the exposure and development of the silver-halide layer.
  • the intermediate layer may howcver also be utilized for influencing the treatment of the silver-halide layer.
  • some developer or some fixing salt may be admixed to the intermediate layer, or, if more than one-intermediate layeris provided, one of the agents may be admixed to one, and the other agent to the other intermediate layer. In this manner the developing and/or fixing of the silverhalide layer is greatly accelerated.
  • Substances such as ammonia, ether or the like, or a m ixture thereof, as described above, may also be admixed to the intermediate layer or layers.
  • intermediate layer in which the gelatine is bound by a dispersed hardener, permits reducing the silver-halide layer to a. softer condition than would be practicable without the intermediate layer, because the silver-halide layer, if softened to a condition in which it would come off a glass or celluloidbacking, will still stick to the intermediate layer which, being hardened, retains the silver-halide layer.
  • the outer intermediate layer 5 may contain an admixture of a developer, while the inner intermediate layer 6 may contain an admixture of fixing salt.
  • the layers may be hardened to different degrees of hardness, the
  • the inner layer i is-softened in its turn and'libcrates the fixing salt.
  • the hardness of the intermediate layers should increase in the direction from the silver-halide layer -4- toward the support or'backing 3.
  • the method of producing a printing plate comprising exposing and developing a light-sensitiveizsilyer-hallde, layer, treating. said layer so as to cause the silver particles therein to become rearranged to form a screen, exposing a sensitized metal plate throughsaid layer, and etching said plate.
  • the method of producing a printing. plate comprising exposing and developing a light-sensitive silver-halide layer, treating said layer so as to cause the silver particles. therein to become rearranged to form a screen, exposing the lightsensitive chromate'layer of a metal plate through said silver-halide layer, treating said chromate layer so that certain portions thereof expose the metal of the plate. and etching said metal plate.
  • the method of producing a printing plate comprising treating a light-sensitive silver-halide layer so as to produce. therein a photographic image and cause the -silver particles in the layer to become rearranged, resulting in the formation of a screen in said layer, making a printing surface from said layer, and treating said surface for obtaining a. printed reproduction resembling a line etching.
  • the method of producing a printing plate comprising treating a light-sensitive silverhalide layer so as to produce therein a photographic image and cause the silver particles in the layer to become-rearranged, resulting in the formation of a screen in said layer, making a printing surface from said layer, and treating said surface for obtaining a printed reproduction resembling a half-tone engraving;

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photosensitive Polymer And Photoresist Processing (AREA)
  • Printing Methods (AREA)
US126933A 1933-01-16 1937-02-20 Method of producing a printing plate Expired - Lifetime US2130735A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
BE394468D BE394468A (fr) 1933-01-16
DEE43807D DE665893C (de) 1933-01-16 1933-01-17 Verfahren zur photomechanischen Herstellung von Druckformen nach in den Toenen zerlegten photographischen Silberbildern
FR751051D FR751051A (fr) 1933-01-16 1933-02-17 Couches <<tramées>> avec images à l'argent ou analogues
DK51780D DK51780C (da) 1933-01-16 1933-02-17 Hinder med Solvbilleder og lignende Billeder med Raster samt Fremgangsmaade til sammes Fremstilling.
GB5072/33A GB415399A (en) 1933-01-16 1933-02-18 Improvements relating to photo-mechanical printing processes
US126933A US2130735A (en) 1933-01-16 1937-02-20 Method of producing a printing plate

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE415399X 1933-01-16
US698671A US2071821A (en) 1931-04-18 1933-11-18 Photographic image bearer and method of making same
US126933A US2130735A (en) 1933-01-16 1937-02-20 Method of producing a printing plate

Publications (1)

Publication Number Publication Date
US2130735A true US2130735A (en) 1938-09-20

Family

ID=32045516

Family Applications (1)

Application Number Title Priority Date Filing Date
US126933A Expired - Lifetime US2130735A (en) 1933-01-16 1937-02-20 Method of producing a printing plate

Country Status (5)

Country Link
US (1) US2130735A (fr)
BE (1) BE394468A (fr)
DK (1) DK51780C (fr)
FR (1) FR751051A (fr)
GB (1) GB415399A (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2977228A (en) * 1957-12-20 1961-03-28 Sperry Rand Corp Method of making three dimensional models
US3655381A (en) * 1969-04-24 1972-04-11 Eastman Kodak Co Process for the production of integrally formed, random dot photographic images
FR2407500A1 (fr) * 1977-10-28 1979-05-25 Bates As Ab Procede de preparation de films negatifs ou positifs pour impression en polychromie
US5067271A (en) * 1988-03-01 1991-11-26 Joergensen Henning Imprisoning trap
US6406833B1 (en) * 1994-07-13 2002-06-18 Jean-Marie Nouel Use of frequency-modulated screening for lightening offset printing surfaces

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2977228A (en) * 1957-12-20 1961-03-28 Sperry Rand Corp Method of making three dimensional models
US3655381A (en) * 1969-04-24 1972-04-11 Eastman Kodak Co Process for the production of integrally formed, random dot photographic images
FR2407500A1 (fr) * 1977-10-28 1979-05-25 Bates As Ab Procede de preparation de films negatifs ou positifs pour impression en polychromie
US5067271A (en) * 1988-03-01 1991-11-26 Joergensen Henning Imprisoning trap
US6406833B1 (en) * 1994-07-13 2002-06-18 Jean-Marie Nouel Use of frequency-modulated screening for lightening offset printing surfaces

Also Published As

Publication number Publication date
GB415399A (en) 1934-08-20
DK51780C (da) 1936-06-22
FR751051A (fr) 1933-08-26
BE394468A (fr)

Similar Documents

Publication Publication Date Title
US2130735A (en) Method of producing a printing plate
US2500877A (en) Photographic stencil screen and method of making the same
US2071821A (en) Photographic image bearer and method of making same
US2947626A (en) Reproduction of photographs on ceramics
US2013116A (en) Photographic matrix
US1957433A (en) Method of making a photographic printing plate
US1482612A (en) Potassium-bichromate process of photographic reproduction
DE509762C (de) Verfahren zur Herstellung von Reflexkopien
US744223A (en) Photographic reproductive process.
US2046326A (en) Color reproduction process
US506109A (en) Half-tone negative for photo processes
US2668762A (en) Process of producing screens
US2692198A (en) Methods of producing half-tone printing plates
US3156562A (en) Reproduction of photographic images on ceramic surfaces
US1794693A (en) Screen employed in photo-engraving and method for making the same
US1695284A (en) Color photograph or film and method of producing same
US1645112A (en) Process of photographic copying by the reflection method
US2236417A (en) Process of producing colored prints
US153577A (en) Improvement in methods of retouching photographic negatives
US1477866A (en) Producing printing surfaces
Defibaugh The Collotype: History, process & photographic documentaion
US865276A (en) Art of etching.
US818574A (en) Half-tone photolithography and the like.
US1433806A (en) Preparation of plates for printing by greasy ink
US1889124A (en) Color photography