Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
  • B41N3/00—Preparing for use and conserving printing surfaces
  • B41N3/003—Preparing for use and conserving printing surfaces of intaglio formes, e.g. application of a wear-resistant coating, such as chrome, on the already-engraved plate or cylinder; Preparing for reuse, e.g. removing of the Ballard shell; Correction of the engraving
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F1/00—Etching metallic material by chemical means
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
  • C25F3/00—Electrolytic etching or polishing
  • C25F3/02—Etching
  • C25F3/14—Etching locally

Definitions

• an area in which the etching cavities are too shallow may be subjected to a second etching process by applying a stiff paint to the lands (i.e. the portions of the cylinder surface that have not been affected by the etching treatment) in the area to be retouched and subsequently etching said area with a solution of iron chloride so as to make the etching cavities deeper. It is not easy to correctly perform this method because the second etching process is liable to deepen the etching cavities too much and to damage the lands. Such a retouching cannot be undone any longer.
• a Wrong etching or a damaged area may be made plain again by filling the etching cavities or the damaged area with solder or a thick liquid paste which will harden after being dried.
• solder or a thick liquid paste which will harden after being dried.
• This invention relates to a method of retouching etchings in intaglio printing cylinders by changing the depth of the etching cavities in the area to be retouched, which method is characterized in that this is effected either by applying an insulating layer to the lands and changing the depth of the etching cavities by galvanic etching or by precipitating metal therein, or in the alternative by applying an insulating layer to the etching cavities and changing the height of the lands by precipitating metal thereon or by etching the lands galvanically or chemically, whereupon the insulating layer is removed again.
• auxiliary metal layers Patented Aug. 23, 1960 ice may have a different function. They may serve as an intermediate layer promoting the adherence of the metal to be precipitated on the lands or in the etching cavities or of a second layer of metal, which is to cover the entire area to be retouched, to the base metal. It is also possible to apply a layer of metal which will dissolve in an etching agent which will not attack the base metal. Furthermore it is possible to apply two layers of metal of which the upper layer will dissolve in the etching agent to be used, whereas the lower will not be attacked. In this case an etching agent may be used in which the base metal will dissolve, because said base metal will be protected by the lower layer, the so called etching retarding layer, from the action of the etching agent.
• the etching may be deepened by galvanically etching the etching cavities in the area to be retouched to a greater depth after insulating the lands.
• This method for example, very well lends itself to be applied to copper intaglio printing cylinders.
• the metal of the intaglio printing cylinder is the metal of which the surface of said cylinder consists, also if said metal only constitutes the coating of a cylinder consisting of another metal, because the latter metal does not play a part in the printing operation.
• the etching may be made less deep by insulating the etching cavities and by removing the upper portion of the lands by a galvanic or chemical etching treatment.
• Another simple correction method consists in that after insulating the etching cavities metal is precipitated on the lands or after insulating the lands metal is precipitated in the etching cavities. In the first instance the etching is deepened, in the second case it is rendered shallower.
• This method for example, is suitable for brass cylinders on which copper may be galvanically precipitated without any difliculty.
• an acid resistant paste may be successfully used, which paste may consist for example of a mixture of a wax and an asphalt lacquer.
• the etching cavities in the area to be retouched are filled with this paste, the lands remaining free.
• a metal for example nickel, which is applied to the entire area to be retouched and which is subsequently removed from the lands by polishing, so that on said lands the original metal surface is laid bare again.
• the metal introduced into the etching cavities should then be such that it will not dissolve in the etching agent of the base metal.
• the lands may be insulated by applying a stifi, acid resistant paint, for example book-printing or offset ink, to the lands in the area to be retouched by means of rollers, the etching cavities remaining unfilled.
• a stifi, acid resistant paint for example book-printing or offset ink
• the remainder of the cylinder should be protected during the treatment of said part.
• this may be effected by using a stencil which leaves the area to be retouched uncovered or by glueing a stencil on the area to be retouched, covering the surrounding part with an insulating lacquer, for example a mixture of an asphalt lacquer and a plasticizer, and subsequently removing the stencil again.
• an insulating lacquer for example a mixture of an asphalt lacquer and a plasticizer
• the entire area to be retouched may be treated with the etching acid, so that the remaining zinc will be dissolved and the plate is again restored to its original condition.
• chromium-plated cylinder which is not attacked by the majority of etching agents.
• many metals do not adhere to chromium it is mostly desirable first to provide an intermediate coating over the entire area to be retouched and to precipitate thereon the metal proper to be etched.
• This last layer of metal may be for example a layer of nickel or a layer of another hard metal. After this treatment, therefore, the entire area to be retouched has been heightened by two layers of metal without the difference in height between the lands and the etching cavities being changed.
• the etching cavities or the lands in the area to be corrected are insulated. If now the etching is carried out with a suitable etching agent in which both metals will dissolve, the two layers will be removed by the etching down to the chromium in the uncovered places, so that a corresponding lowering or heightening of the lands relative to the etching cavities will be obtained.
• the correction may be entirely undone by removing the insulating substance and by etching the entire area to be retouched. The portions of the two layer of metal left behind on the insulated places will then be dissolved, so that the plate is restored to its original condition.
• the chromium may also be coated with an intermediate layer and layer of copper and after insulating the lands or the eching cavities the copper and the intermediate layer may be removed by etching with an iron chloride solution.
• Another method consists in the application of a socalled etching retarding layer which will not dissolve in the etching agent.
• the etching agent will then only act on the metal provided on top of said layer, but will not attack the metal of the cylinder. 7
• a copper cylinder provides the entire area to be retouched with a layer of nickel and deposit a layer of copper on said. layer of nickel. After insulating the lands or the etching cavities the cylinder is etched with an etching agent for copper which does not attack nickel e.g., a mixtureofchromic acid and sulfuric acid. In the uncovered places only the 4 upper layer of copper will be attacked, but the nickel and the metal of the cylinder.
• an etching agent for copper which does not attack nickel e.g., a mixtureofchromic acid and sulfuric acid.
• a retouch thus obtained also oifers the advantage that the correction may be undone by treating the entire retouched area with the etching agent.
• the remainder of the upper layer of copper will dissolve then, so that only the layer of nickel is left, which, however, uniformly covers the original surface and which, therefore, has no influence on the difference in height between the lands and the etching cavities.
• the depth of the etching cavities in chromium plate copper cylinders may be modified by a double etching treatment while using etching retarding layers.
• the chromium on the lands or in the etching cavities is removed and subsequently the bared copper is removed.
• an insulating mass in the etching cavities galvanically apply a nickel-cobalt layer and subsequently a copper layer to the lands.
• the nickel-cobalt'layer then serves as an intermediate layer to improve the adherence of the copper to the chromium.
• the chromiurn' is removed from said etching cavities by etching with hydrochloric acid, the copper on the lands acting as an etching retarding layer.
• the plate is then etched with an etching agent for copper, for example an iron chloride solution.
• a similar result may be obtained by applying to the entire area to be retouched of the chromium plated copper intaglio printing cylinder an intermediate layer consisting of nickel cobalt and subsequently a copper layer.
• the plate is first etched with process an etching agent for copper, whereby the nickel-cobalt layer is also dissolved and subsequently with an etching agent for chromium.
• the insulating mass is removed and the relative area is etched again with the etching agent for copper.
• the bared copper in the etch ing cavities will thereby be further etched,.while the copper layer and the nickel-cobalt layer on the lands will also dissolve.
• the layer of chromium laid bare by this second etching treatment will, however, act as an etching retarding layer, so that the height of the lands remains unchanged, whereas the etching cavities become deeper.
• the insulating mass may again be provided in the etching cavities instead of on the lands. The ultimate result then will be that the height of the lands is reduced relative to the bottom of the etching cavities.
• auxiliary metal layers When making corrections While using auxiliary metal layers it often occurs that owing to the difference in height in the corrected and the non-corrected area of the cylinder a difference in tone will be obtained, so that a separating line between the corrected and the non-corrected area of the cylinder will be visible. This difliculty may be met by providing the auxiliary layer or layers over an area larger than the area to be corrected.
• the method according to the invention may also be employed for entirely filling up etchings and for making scratches and other defects invisible. If an etching or such a defect has been filled up a new etching may be provided on the area this treated.
• the corrections obtained according to the invention may be intensified or weakened without the provision of an insulating layer, by subjecting the corrected area to such a treatment that only on one of the two metals a layer of metal is deposited or that only one of the two metals is removed by etching.
• the first method is of special importance for chromium-plated cylinders, because most metals will be e.g. copper, will not properly adhere to chromium, so that it is easy to carry out the method so as to deposit the metal only on the auxiliary metal.
• the second method may be used both for copper cylinders and to chromium-plated cylinders.
• Example I The pre-treatment of the cylinder is the same as in Example I, but instead of precipitating copper onto the lands, said lands are etched galvanically or chemically. In this manner a cylinder is obtained in which the etching has become less deep in the area retouched.
• Example 111 On a copper intaglio printing cylinder the lands both in the area to be corrected and in the surrounding area are covered with an oflFset ink by means of a roller. A stencil is glued on the area to be corrected whereupon the surrounding area is covered with an acid resistant lacquer. The stencil is subsequently removed and the etching cavities in the area to be corrected are filled either galvanically or chemically with copper to such an extent that the depth of the etching is reduced to the desired extent. The insulating lacquer and paste are then removed.
• Example IV The cylinder is treated in the same manner as in example III, but instead of filling the etching cavities with copper they are etched galvanically. In this way the etching is deepened.
• Example V Both on the area to be corrected and on the surrounding part of a copper intaglio printing cylinder a layer of nickel is deposited galvanically. Copper is then deposited galvanically on an area larger than the area to be corrected, but smaller than the area covered by the layer or" nickel. The area to be corrected, therefore, is covered with two uniform layers of metal, but the depth of the etching is unchanged.
• a stencil surrounding the area to be corrected is now glued onto the cylinder and in said area the lands are insulated by means of an acid resistant paint. Said area is then etched with a chromic acid-sulphuric acid solution effected, which dissolves the copper, but not the nickel. It is possible to continue the etching down to the layer of nickel or to a lesser extent. Thereafter the mea to be corrected is entirely covered with an acid resistant lacquer, the stencil is removed and in the area surrounding the area to be corrected the copper is removed down to the etching retarding layer by means of a chromic acid-sulphuric acid solution
• Example VI The procedure is the same as in the preceding example, the difference being however, that in the area surrounded by the stencil not the lands, but the etching cavities are insulated. In this case the etching is made less deep by etching the copper on the lands away down to the etching retarding layer.
• Example VII On a copper cylinder a layer of zinc is provided galvanically, said layer covering both the area to be corrected and the surrounding area.
• a stencil enclosing said area is glued onto the cylinder and said area is insulated by means of an acid resistant lacquer.
• the cylinder is etched with a zinc etching acid, so that all of the zinc surrounding the area to be corrected is removed.
• the acid resistant lacquer is then removed from the area to be corrected and the etching cavities are filled with an insulating paste, whereupon the zinc on the lands is removed by etching. By this treatment the etching has become less deep.
• Example Vlll On a chromium-plated intaglio printing cylinder the etching cavities both in the area to be corrected and in the surrounding part are filled with an insulating paste, whereupon a stencil is glued onto the area to be corrected. The surrounding part is subsequently insulated with lacquer whereupon the stencil is removed. A nickelcobalt layer is galvanically applied to the lands as an intermediate layer and a layer of nickel is galvanically deposited on the intermediate layer. Thereafter the insulating lacquer and the insulating paste are removed again.
• Example IX A chromium-plated cylinder is provided galvanically both on the area to be corrected and on the surrounding part, with a nickel-cobalt layer as an intermediate layer and thereafter with a layer of nickel.
• the lands are covered with an insulating paint by means of a roller and the etching cavities are etched down to the chromium with a solution of iron chloride in water.
• a stencil surrounding the area to be corrected is then glued on the cylinder and said area is entirely covered with an in sulating lacquer. After the removal of the stencil the underlying part is etched down to the chromium, whereupon the insulating lacquer is removed.
• Example X The area to be retouched of a chromium-plated cylinder is covered with a stencil and the surrounding area is coated with an insulating lacquer. After removal of the stencil the non-coated area is galvanically provided with an intermediate layer consisting of nickel-cobalt and a copper-layer, whereupon the etching cavities in Example X1
• a similar result may be obtained by galvanically depositing the intermediate layer and the copper layer both on the area to be retouched and on the surrounding part of the'cylinder referred to in the preceding example, insulating the etching cavities with a paste and etching the copper and the intermediate layer on the lands away by means of an iron chloride solution.
• Example XII The methods described above for deepening the etching in chromium-plated cylinders only give good results if the correction to be made is slight. If the lands are heightened to a great extent, the'difiiculty is encountered thatafter printing a line ofcontrast between the corrected and the non-corrected area will be clearly visible. In this case the method may better be carried out as follows:
• Both the area to be corrected and the surrounding area are galvanically heightened with an intermediate layer of nickel-cobalt and a superposed layer of nickel.
• the lands are then covered with an insulating paint by means of a roller and a stencil is glued onto the area to be corrected.
• the stencil is removed and in the area to be corrected the nickel and the intermediate layer are removed from the etching cavities by an etching treatment with an iron chloride solution.
• an insulating paste is provided in the etching cavities of the area to be retouched.
• an intermediate layer consisting of nickel-cobalt and subsequently a layer of copper is galvanically deposited.
• the chromium in the etching cavities is removed by etching down to the copper with hydrochloric acid.
• the area is then etched with a solution of iro n chloride in water, whereby the etching cavities are etched deeper, while at the same time the copper layer and V the nickel-cobalt layeron the lands will dissolve.
• the insulating lacquer is removed. As a result of the above treatment the etching has become deeper.
• Example XIV cally coated with an intermediate layer consisting of nickel-cobalt and subsequently with a layer of copper.
• the lands are then insulated by means of an insulating taglio printing form which .of the printing form is copper,
• the etching with an iron chloride solution is repeated so that the etching cavities are etched further, whereas on the lands only the layerof copper and the layer of nickel-cobalt will be removed. Finally the in sulating paint is removed.
• a method of retouching an etching in a metal inhas a screen bridge portion and an etching cell portion, comprising the steps of coating one of said portions in the area to be retouched with a non-metallic etching agent resisting'material, depositing at least one auxiliary metal layer on the other of said portions, removing said etching agent resisting material and etching said area. with an etching agent capable of dissolving the metal of the printing form and incapable of dissolving the auxiliary metal.
• a method of retouching an etching in a metal intaglio printing form which has a screen bridge portion and. an etching cell portion comprising the steps of coating one of said portions in the area to be retouched with a non-metallic etching agent resisting material, depositing at least one auxiliary metal layer on the other of said portions, removing said etching agent resisting material, etchcapable of dissolving form and incapable of dissolving the auxiliary metal, and subsequently etching said area with an etching agent capable of dissolving the auxiliary metal and incapable of dissolving the metal of said printing form.
• a method according to claim 3 in which the metal of the printing form is chromium and copper, the chromium being in the form of a thin coating on copper, two auxiliary metal layers are provided, the first of which consists of an alloy of nickel and cobalt and the second of copper, the first etching agent is a solution of hydrochloric acid and the second etching agent is a solution of ferric chloride, the treatment with the hydrochloric acid solution being continued until the chromium coating on the areas exposed to said hydrochloric solution is completely dissolved so that by the subsequent treatment with the solution of ferric chloride both the copper of the second auxiliary layer and the copper of the printing form in the surface portion where the chromium has been dissolved are attacked.
• a method of retouching an etching in a metal base intaglio printing form which has a screen bridge portion and an etching cell portion comprising the steps of de positing at least one auxiliary metal layer over the whole area to be retouched, coating one of said portions with a non-metallic etching agent resisting material, changing the height of the other of said portions by etching said area with an etching agent capable of dissolving the auxiliary metal, but incapable of dissolving the base metal, and removing said etching agent resisting material.
• a method of retouching an etching in a metal base intaglio printing form which has a screen bridge portion and an etching cell portion comprising the steps of depositing two auxiliary metal layers over the whole area to be retouched, coating one of said portions with a nonmetallic etching agent resisting material, changing the height of the other of said portions by etching said area with an etching agent capable of dissolving the upper auxiliary metal but incapable of dissolving the lower auxiliary metal, and removing said etching agent resisting material.
• a method of retouching an etching in a metal base intaglio printing form which has a screen bridge portion and an etching cell portion comprising the steps of depositing two auxiliary metal layers over the whole area to be retouched, coating one of said portions with a nonmetallic etching agent resisting material, changing the height of the other of said portions by etching said area with an etching agent capable of dissolving both auxiliary metal layers, but incapable of dissolving the base metal and removing said etching agent resisting material.
• a method of retouching an etching in a metal base intaglio printing form which has a screen bridge portion and an etching cell portion comprising the steps of de positing at least one auxiliary metal layer over the Whole area to be retouched, coating one of said portions with a non-metallic etching agent resisting material, changing the height of the other of said portions by etching said area with an etching agent capable of dissolving the auxiliary metal and subsequently with an etching agent capable of dissolving the base metal but incapable of dissolving the auxiliary metal, and removing said etching agent resisting material.
• a method of retouching an etching in a metal base intaglio printing form which has a screen bridge portion and an etching cell portion comprising the steps of depositing at least one auxiliary metal layer over the whole area to be retouched, coating one of said portions with a non-metallic etching agent resisting material, changing the height of the other of said portions by etching said area with a first etching agent capable of dissolving the auxiliary metal but incapable of dissolving the base metal, and subsequently with a second etching agent capable of dissolving the base metal but incapable of dissolving the auxiliary metal, removing said etching resisting material and etching said area with a third etching agent capable of dissolving the auxiliary metal so as to remove the same from the first mentioned portion.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Printing Plates And Materials Therefor (AREA)
• ing And Chemical Polishing (AREA)
• Manufacture Or Reproduction Of Printing Formes (AREA)

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Citations (14)

• 0
  • BE BE544257D patent/BE544257A/xx unknown
  • NL NL194000D patent/NL194000A/xx unknown
  • NL NL88707D patent/NL88707C/xx active
  • DE DENDAT1071099D patent/DE1071099B/de active Pending
• 1955
  • 1955-12-02 CH CH355465D patent/CH355465A/de unknown
• 1956
  • 1956-01-09 US US557841A patent/US2950181A/en not_active Expired - Lifetime
  • 1956-01-11 GB GB1014/56A patent/GB823854A/en not_active Expired
  • 1956-01-13 FR FR1150664D patent/FR1150664A/fr not_active Expired

Patent Citations (14)

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