Abstract: A method of forming an image is disclosed in which chemically active toner particles are used to trigger image amplification chemistry after their attraction to an electrostatic charge pattern.The method of forming an image comprises applying electrographic toner particles to a charge pattern on a support followed by a chemical amplification processing step comprising heating the toner image in the presence of an image-receiving element comprising:(a) a cobalt(III) complex capable of releasing an amine on processing, and(b) an amplifier which, on reaction with an amine:(i) forms a dye or dye precursor, or(ii) reduces the cobalt(III) complex, resulting in the release of additional amine,said toner comprising an activator which, under the conditions of processing releases an amine either directly or indirectly.

Abstract: Disclosed is a useful method of removing a charge from an electrophotographic photoreceptor provided with insulation layers on its surface by radiating light containing a minimum of 6,000 angstroms of peak wave length onto said photoreceptor simultaneously with a corona discharge. To realize this, a filter is applied so that light containing a minimum of 6,000 angstroms of peak wave length can be generated.

Abstract: The invention provides an electrophotographic method of forming a subsequent toner image overlapping one or more toner images previously formed on a surface of an electrophotographic element.The method comprises the steps of:(a) electrically charging the surface and the previously formed toner image or images,(b) forming an electrostatic latent image overlapping the previously formed toner image or images on the surface by imagewise exposing the element, through the previously formed toner image or images, to actinic radiation of a wavelength outside the range of 400 to 700 nanometers; the density of the previously formed toner image or images to the actinic radiation being less than about 0.2, and(c) electrographically developing the electrostatic latent image to thereby form the subsequent toner image.

Abstract: A photoreceptive sheet having a surface adapted to carry a reproductive image, the surface of the sheet bearing a photoreceptive layer including a microfoam of a plurality of voids in a mixture of a photoconductive substance and an insulating binder, the photoreceptive layer being capable of receiving an electric charge, responding photoelectrically to light, and discharging photoconductively to form the image.

Abstract: A cyan-free desensitizing solution for use in offset printing comprising as the effective ingredients:(a) at least one member selected from the group of an ammonium salt and amine salt of inositol hexaphosphate ester;(b) a water-soluble cationic polymer; and(c) a low molecular weight electrolyte.

Abstract: Raised Xerographic printing is produced by the use of thermally intumesced electroscopic powders for the development of electrophotographic images. Intumescent electroscopic powders are belended with the powdered pigmented "ink" or "Toner" in the ink reservoir of a Xerographic copying machine. The image is formed and transferred to a paper carrier in the well-known process of Carlson, U.S. Pat. No. 2,297,691. The heat used in thermoadhesively attaching the "Toner" to the paper carrier also causes great intumescence of the intumescent powder, resulting in a raised image. The image is similar in appearance and texture to "engraving" or raised thermographic printing. It can be read by the sightless by tactile recognition. The intumescent powder used is made of vinylidene-chloride-acrylonitrile-isobutane as described by the inventor in his Disclosure Document No. 001078 filed in the U.S. Patent Office on Dec. 22, 1969.

Abstract: An improved method of controlling toner concentration for electrophotographic copying apparatus employing a dual component developing material which is composed of toner particles and magnetic particles. The method is arranged to detect the amount of magnetic particles adhering onto a photosensitive member for controlling the toner replenishing amount according to the amount of the magnetic particles thus detected.

Abstract: Disclosed is a method for the xerographic, pattern-wise deposition of a dielectric powder that is sensitized with a metal compound to enable the electroless plating of a pattern formed by said powder.

Abstract: The present invention relates to a graphic arts film obtained by forming a toner image on a light-transmitting base sheet having a toner-adhesive and ink-repellent coating layer, then fixing the toner image and applying ink onto the surface of the base sheet to thereby selectively enhance the optical density of the toner image area on the coating layer, and a method of preparing the same.The present invention permits easy and inexpensive production of a graphic arts film having a sufficiently enhanced optical density, free from pin-holes and capable of being retouched with respect to the image formed thereon.

Abstract: A process for producing a printing plate and a printing plate making machine are disclosed. The process involves providing an electrophotographic plate making material which includes a base having a low conductive layer thereon. The material is electrically charged and imagewise exposed. The imagewise exposed material is subjected to liquid toner development with a toner containing a solvent. The solvent is then substantially removed by heating the material to a temperature sufficient to cause the evaporation of the solvent. The material is then moved to a substantially isolated fixing area and again heated in order to fix a toner image on the plate making material. The process can be quickly and easily carried out and eliminates the danger of the explosion of solvent vapors.

Abstract: An electrostatic image is developed by selectively extracting colored grains of one polarity from a mixture containing colored grains having opposite polarity to each other in the presence of an alternating field followed by development of the electrostatic image by the selectively extracted colored grains.

Abstract: An image formation method and apparatus utilizing the technique of removing a conductive one-component developer which adheres to the non-image bearing portion of an image bearing member such as a photosensitive member and provides the background fog of the image on the image bearing member. More particularly, it discloses an image formation method and apparatus in which one-component developer conductive particles are brought into contact with the developer forming the fog to thereby induce in said particles a charge of the opposite polarity to the polarity of the charge of the developer and the particles and the developer are attracted to each other by the coulomb force thereof, whereafter with the conveyance force of said particles, said developer is removed to thereby form a fogless image.

Abstract: The disclosure is directed to light-transmitting image forming particles each containing at least a colorless subliming dye which develops color through reaction with a color developing agent, and also a coloring agent, and moreover, having at least a pair of parallel faces. When applied to a particular image forming process as disclosed, the particles can provide color images with an expanded latitude and a superior color purity, while, by bevelling or planing-off the edges defining the parallel faces, exposure amount may be reduced as compared with particles without such bevelling.

Abstract: A water fixable toner powder is provided for making powder images that can be transferred and fixed with good image quality onto receiving material such as paper by being covered with water, squeegeed and subsequently pressed against the receiving material. The individual particles of the toner powder consist essentially of hydrolyzed polyvinyl ester that is swellable but insoluble in water at a temperature up to 30.degree. C., such preferably as polyvinyl alcohol having a degree of hydroylsis above 98% and an average molecular weight of at least 4,000, together with finely divided filler material that is insoluble and non-swellable in water and is present in an amount of between 10 and 60% by volume. Other additives such as coloring material and/or a polarity control agent may also be present in the binder of hydrolyzed polyvinyl ester. Preferred forms of the toner particles are porous and have a specific surface of between 0.6 and 2m.sup.2 /g.

Abstract: A method for amplifying an electrostatic, charge-differential pattern is disclosed. The method comprises (a) imagewise forming a first toner deposit by developing a first electrostatic pattern having a first charge differential per unit area whose maximum value is no greater than a preselected level, (b) in an image-amplification element comprising a charge-holding surface layer overlying a field-supporting electrode, forming a current-carrying path between the toner deposit and the field-supporting electrode, (c) under conditions in which nontoned regions are not photoexcited, overall charging the image-amplification element with sufficient charge to form an enhanced electrostatic charge pattern having a second charge differential per unit area whose maximum value is greater than the preselected value in step (a), and (d) developing the enhanced charge pattern into a second toner deposit.

Abstract: Polymeric photoconductors are disclosed comprising a condensation polymer backbone containing, as repeating units, the condensation residues of (1) a diacid, and (2) an organic difunctional compound capable of undergoing condensation polymerization with said diacid, and an arylamine photoconductor group appended to at least one of said diacid or said organic difunctional compound residues.A preferred polymeric photoconductor is ionic and comprises a condensation copolymer containing, in addition to the above described repeating units, the condensation residue of a second diacid containing an anionic iminodisulfonyl or sulfo group. In certain embodiments, the ionic arylamine-containing polymers are water-dispersible copolyesters.The polymeric photoconductors described are useful in photoconductive compositions and elements. Electrophotographic processes employing such elements are also disclosed.

Abstract: Process for toning imagewise tacky surfaces by multiple application of at least two toners containing different low melting compounds having a polar substituent and melting in the range of 25.degree. to 110.degree. C., which in contact with one another render the toners tacky at room temperature thus yielding higher color density or change of color tone.

Abstract: Raised Xerographic printing is produced by the use of thermally intumesced electroscopic powders for the development of electrophotographic images. Intumescent electroscopic powders are belended with the powdered pigmented "ink" or "Toner" in the ink reservoir of a Xerographic copying machine. The image is formed and transferred to a paper carrier in the well-known process of Carlson, U.S. Pat. No. 2,297,691. The heat used in thermoadhesively attaching the "Toner" to the paper carrier also causes great intumescence of the intumescent powder, resulting in a raised image. The image is similar in appearance and texture to "engraving" or raised thermographic printing. It can be read by the sightless by tactile recognition. The intumescent powder used is made of vinylidene-chloride-acrylonitrile-isobutane as described by the inventor in his Disclosure Document No. 001078 filed in the U.S. Patent Office on Dec. 22, 1969.

Abstract: In an electrophotographic process for producing a display screen on the window of a color display tube, a step is performed which increases the potential difference between areas of the screen which have been charged to attract charged particles of a screening material and areas of the screen not charged to attract such particles. This increased potential difference increases the attraction force, thereby improving particle retention until the screening material is permanently attached.

Abstract: In a method for electrophotography comprising an electrostatic transfer process, after an electrostatic latent image formed on a surface of a photoconductive and photosensitive member has been developed with toner, the surface of the photoconductive and photosensitive member and a toner image are charged at the same polarity as the electrostatic latent image and thereafter the toner image is electrostatically transferred onto a recording medium to obtain a record.

Abstract: Polymeric photoconductors are disclosed comprising a condensation polymer backbone containing, as repeating units, the condensation residues of (1) a diacid, and (2) an organic difunctional compound capable of undergoing condensation polymerization with said diacid, and an arylamine photoconductor group appended to at least one of said diacid or said organic difunctional compound residues.A preferred polymeric photoconductor is ionic and comprises a condensation copolymer containing, in addition to the above described repeating units, the condensation residue of a second diacid containing an anionic iminodisulfonyl or sulfo group. In certain embodiments, the ionic arylamine-containing polymers are water-dispersible copolyesters.The polymeric photoconductors described are useful in photoconductive compositions and elements. Electrophotographic processes employing such elements are also disclosed.

Abstract: A bimodal electrophotographic apparatus and process which incorporates capabilities for making both positive and reversal copies. One surface of a layer of a zinc oxide coated paper, or the like, is given an initial electrostatic charge. The charged surface is then exposed to an image having light and dark areas for causing surface charge to dissipate, in varying degree depending on the amount of light striking the charged paper, in the exposure areas. A charged toner is applied to the zinc-oxide-coated paper by a magnetic brush. In the reversal mode, the brush has a bias potential. The brush is formed by an aggregation of magnetic toner particles clinging to the outside of a cylindrical sleeve while magnets inside the sleeve rotate. The toner collects on the paper to form an image depending upon where the charge is dissipated.

Abstract: An electrophotographic method, in which a dielectric film is contacted with a surface of a charged and exposed electrophotographic layer and said film is acted on by positive and negative ions of the same concentration from a source of ions, which settle on the film and produce a latent image thereon. Then the electrophotographic layer is illuminated by an actinic light source to preserve the latent image on the film and the film is separated from the electrophotographic layer while being illuminated or after that. Thereafter the latent image obtained on the film is developed and fixed.

Abstract: Fusing both small and large image areas of dry resinous marking particles supported on the surface of a receiver member by irradiating the particles with energy to at least partially melt the particles at the interface between the particles and receiver member. Fusing is accomplished by directing the energy from an energy source toward the surface of the particle-supporting receiver member along a path having a major low-angle component relative to the receiver member. The particles are irradiated over a substantial portion of their surface area, with energy which is not reflected by the receiver member and with energy which has been reflected by the receiver member. A sufficient amount of energy is thus received to at least partially melt the particles at the interface between the particles and receiver member so that the particles adhere to the receiver member.

Abstract: The present invention provides a developing method for rendering a latent image supported on an image bearing member visible, and an apparatus therefor, in which a developer supporting member supporting thereon spherical granular developer prepared in substantially spherical form by a flow coater process or a spray drying process is maintained in opposed relation to an electrostatic image bearing member having a backing electrode so that the surface of the image bearing member and the developer on the developer supporting member are maintained in a mutually contact-free state, and an alternating voltage is applied to the developer supporting member to cause reciprocating motion of the developer in the developing area between the developer supporting member and the image bearing member.

Abstract: In the process of forming an electrostatic latent image on a photosensitive medium through at least two kinds of charging steps, the electrostatic latent image is stabilized by the steps of measuring the dark region potential V.sub.D and the light region potential V.sub.L on the photosensitive medium, comparing the measurement values with a predetermined referential dark region potential V.sub.DR and a predetermined referential light region potential V.sub.LR, and when the differences between the V.sub.D, V.sub.L and the V.sub.DR, V.sub.LR are not within predetermined ranges, setting the amount of control by control functions f(x,y) and g(x,y), in which the differences x=V.sub.DR -V.sub.D and y=V.sub.LR -V.sub.L are variables, and varying the potential of the latent image on the photosensitive medium in accordance with the set amount of control.

Abstract: A photoconductive plate for printing use having imaged and non-imaged portions. The plate comprises an electroconductive support and a photoconductive layer including a photoconductive material comprising an organic photoconductive pigment and a binder comprising an alkaline soluble phenol resin. The photoconductive plate is subjected to heat treatment at a sufficiently elevated temperature prior to removal of portions of the photoconductive layer so that at least 80% by volume of the non-imaged portion of the photoconductive layer is removed when the photoconductive plate is subjected to treatment with a removing solution. A method for preparing a printing plate. An image is formed on a photoconductive layer and the non-imaged portion of the photoconductive layer is removed by treating the layer with a removing solution.

Abstract: A copy paper separating method for use in an electrophotographic copying apparatus which forms a latent electrostatic image on a recording member is provided. The method includes the step of depositing fine particles having insulating properties and charged to a polarity opposite of that of the toner image on the surface of the recording member before the copy paper is placed over the recording member, to cause the particles to reduce the electrostatic attraction between the copy paper and the recording member, thereby facilitating separation of the copy paper from said recording member.

Abstract: An electrophotographic process is provided wherein an electrostatic latent image is developed with finely divided toner particles and then the developed image is fixed by irradiating it with high energy ultraviolet rays or visible light. The toner particles used consist essentially of, based on the weight of the toner particles, (a) 62-99.4 wt. % of a binder resin substantially consisting of a bisphenol A/eplchlorohydrin type epoxy resin having a melting point of 60.degree.-160.degree. C., an epoxy equivalent of about 450-5,500 and a Mw of about 900-8,250, (b) 0.6-8 wt. % of carbon, (c) 0-5 wt. % of a dye and, optionally, (d) 0-20 wt. % of a montanic acid ester wax.

Abstract: A developing apparatus as used in copying machine etc. having a rotary sleeve and a magnetic field generating means arranged in the inside thereof, forming toner gain layer on the surface of the rotary sleeve, and developing the electrostatic images on the electrostatic image holding body by bringing the sleeve surface near the electrostatic image holding body, in which the electrostatic image areas on said electrostatic image holding body and passed through the neighborhood of the magnetic poles of the generating means of magnetic fields different in polarity which and arranged, adjacent to each other, in said sleeve which faces said electrostatic image holding body to develop said electrostatic images and then to remove the fog by using the magnetic pole reverse in polarity to the developing magnetic pole.

Abstract: Improved electrographic development apparatus and procedure for use with partially-conductive developer employs transport of the developer through a first development zone in a direction generally countercurrent to a moving image member and through a second development zone in a direction generally co-current to the moving image member. The extent of image development within each such zone is controlled by the rate of developer transport and/or the magnitude of developer bias, so that overall development of the different portions of large solid image areas (particularly leading and trailing portions of such areas) is equalized.

Abstract: Method and apparatus for image development, wherein a space gap between a latent image holding member and a developer carrying member is made wider, at a developing section, than thickness of the developer layer on the surface of the developer carrying member, and both members are opposed each other for developing operation, and wherein the developer to be used is composed of electrically insulative toner particles having an average particle diameter of from 5.mu. to 30.mu. and very fine particles having a particle diameter smaller than that of the toner particles and capable of assisting electric charging of the toner particles in a polarity opposite to that of the latent image, the fine particles being added to the toner particles and mixed together.

Abstract: Fusing both small and large image areas of dry resinous marking particles supported on the surface of a receiver member by irradiating the particles with energy to at least partially melt the particles at the interface between the particle and receiver member. Fusing is accomplished by directing the energy from an energy source toward the surface of the particle-supporting receiver member along a path having a major low-angle component relative to the receiver member. The particles are irradiated over a substantial portion of their surface area, with energy which is not reflected by the receiver member and with energy which has been reflected by the receiver member. A sufficient amount of energy is thus received to at least partially melt the particles at the interface between the particle and receiver member so that the particles adhere to the receiver member.

Abstract: In an electrically activatable recording element, such as one comprising an electrically conductive support having thereon, in sequence: (a) a polymeric electrically active conductive (EAC) layer, (b) an electrically activatable recording layer comprising (A) a dye-forming coupler, and (B) an oxidation-reduction combination comprising (i) an organic silver salt oxidizing agent consisting essentially of a silver salt of a 1,2,4-mercaptotriazole derivative, with (ii) a reducing agent which, in its oxidized form, forms a dye with the dye-forming coupler, (c) a photoconductive layer separated from (b) by an air gap of up to 20 microns, and (d) an electrically conductive layer; improvements are provided by means of a polymeric EAC layer (a) consisting essentially of a vinyl addition polymer, such as poly(methyl acrylate-co-vinylidene chloride). The recording element is room light handleable and provides a dye image and silver image by dry development processing.

Abstract: In an electrically activatable recording element, such as one comprising an electrically conductive support having thereon, in sequence: (a) a polymeric electrically active conductive (EAC) layer, (b) an electrically activatable recording layer comprising (A) a dye-forming coupler, and (B) an oxidation-reduction combination comprising (i) an organic silver salt oxidizing agent, such as a silver salt of a 1,2,4-mercaptotriazole derivative, with (ii) a reducing agent which, in its oxidized form, forms a dye with the dye-forming coupler, (c) a photoconductive layer separated from (b) by an air gap of up to 20 microns, and (d) an electrically conductive layer; improvements are provided by means of a polymeric EAC layer (a) comprising a halogen containing polyester, such as poly(2,2'-oxydiethylene:2,2'-dimethyl 1,3-propylene 50:50-2,5-dibromoterephthalate) and poly(ethylene:2,2-dimethyl-1,3-propylene 50:50-2,5-dibromoterephthalate).

Abstract: Electrographic image patterns are developed using marking particles containing a catalyst or catalyst precursor. The developed image pattern is then amplified by contacting it with high gain chemical-redox amplification composition.

Abstract: An electrophotographic process for printing a number of copies from a single electrostatic charge latent image once formed on a photosensitive member by projecting an optical image of a document to be copied comprises the following successive steps;(a) a step for effecting a uniform primary electrification with one polarity for the photosensitive member;(b) a step for forming on the uniformly charged photosensitive member, a primary electrostatic latent image corresponding to the image of the document by projecting the document image to the photosensitive member;(c) a step for developing the primary latent image with opaque toner particles having charged in the other polarity to form on the photosensitive member a toned image;(d) a step for placing a transfer member over a surface of the photosensitive member on which surface the toned image has been formed;(e) a step for effecting a secondary electrification with the one polarity from a side of the transfer member and for effecting a secondary exposure also

Abstract: This invention is generally directed to toner compositions comprised of a magnetic material and a resin comprising a polymeric esterification product of 1,4-benzenedicarboxylic acid polymerized with 1,2,4-benzenetricarboxylic aicd-cyclic 1,2-anhydride and 2,2-dimethyl-1,3-propane diol. The magnetic material can act as both the colorant and magnetic substance, or an additional colorant such as carbon black can be utilized. The toners of the present invention in one preferred embodiment are useful for developing magnetic images.

Abstract: This invention generally is directed to methods for developing images, including latent magnetic and electrostatic images, which involves forming latent images on a suitable substrate and contacting the image with a toner comprising a polymeric esterification product of 1,4-benzene-dicarboxylic acid polymerized with 1,2,4-benzenetricarboxylic acid - cyclic 1,2-anhydride and 2,2-dimethyl-1,3-propane diol in a magnetic material. The toner composition described is particularly useful in a magnetic imaging system. The magnetic material can act as both the colorant and magnetic substance, or an additional colorant such as carbon black can be utilized.

Abstract: Disclosed is an adhesive generating layer for use in an overcoated photoreceptor system, this layer containing a generating pigment dispersed in a copolymer of a siloxane and a dihydroxy compound of the formula: ##STR1## wherein R and R' are independently selected from the group consisting of alkyl, substituted alkyl, alkenes, substituted alkenes, aryl and substituted aryl; Y is a dihydroxy radical; and n is a number of sufficient value that the average molecular weight of the resulting silicone copolymer is between about 2,000 and 250,000. Examples of copolymers include those wherein R and R' are alkyl groups such as methyl and Y is a biphenol such as 2,2-bis-(4-hydroxy phenyl)-propane, one preferred material being a methyl octyl siloxane 2,2-bis-(4-hydroxy phenyl)-propane copolymer.

Abstract: A method of removing foreign materials from developers characterized by intermittently supplying a magnetic developer to the peripheral surface of a nonmagnetic sleeve provided with a rotatable magnet roller in its interior, while recovering, at a position a specified distance away from the location of supply of the developer along the sleeve peripheral surface, the forward end portion of a layer of the developer moving along the sleeve peripheral surface in a direction opposite to the direction of rotation of the magnetic roller to thereby remove foreign materials from the magnetic developer.

Abstract: An electrographic recording material comprising a conductive sheet support coated with an electrically insulating layer comprising an intimate blend of a polymeric binder and up to 500 parts of an inert finely divided pigment per 100 parts by weight of polymeric binder. The binder comprises from about 40 to about 90 parts by weight of a poly(vinyl acetal) and from about 10 to about 60 parts by weight of a polystyrene or a poly(.alpha.-methylstyrene). The electrographic recording material exhibits improved toner adhesion.

Abstract: Carrier particles for use in an electrophotographic process are prepared by coating the surface of the carrier particles with a perfluoro carboxylic acid in a polymeric binder. The resulting carriers are long lived and capable of imparting a positive triboelectric charge to electroscopic powders mixed therewith.

Abstract: Apparatus for fusing a toner image carried by a support. The apparatus includes first and second members, at least one of which is heated, which are supported in variable pressure engagement to fuse a toner image carried by a support passed between the members. A sensor senses the temperature of the heated member(s) and the pressure of engagement force is varied as a function of the temperature in order to maintain consistent fused image quality.

Abstract: A photographic speed-increasing concentration of a certain organic photographic speed-increasing electron acceptor provides increased photographic speed in a charge-sensitive recording composite material having an ohmic resistivity of at least about 1.times.10.sup.10 ohm-cm. The charge-sensitive recording material can comprise (a) a first electrically conducting layer in association with (b) a photoconductor layer, (c) an electrically activated recording layer comprising an image-forming combination of (i) an organic, heavy metal salt oxidizing agent with (ii) a reducing agent and (iii) the described speed-increasing electron acceptor, and a binder, and (d) a second electrical conducting layer. This recording material can be room light handleable and can provide a developed image with increased speed by dry development subsequent to electrical exposure.

Abstract: Images of a microfilm on which images of the pages of a book are recorded are alternately and successively formed on an electrophotographic member for printing the obverse surface of a web and on another electrophotographic member for printing the reverse surface of the web. Then, these images formed are transferred and fixed onto the obverse and reverse surface of the web, thereby to complete printings of the respective pages of the book. Finally, the web with the printed images is folded at an interval of one page and the folded web is cut and bound. A consecutive copying and bookbinding apparatus comprises an electrophotocopying apparatus disposed on an image projection path of a microfilm projector provided with projection path changing mirror. Another electrophotocopying apparatus is disposed on a projection path normal to the aforesaid projection path. Rollers are provided to continuously feed the web past these electrophotocopying apparatuses.

Abstract: An electric current conductive composition comprising benzotriazole or a derivative thereof and a substantially electrically insulating binder, which is an essential component of an image recording element. The image recording element comprises a support having thereon a layer of the electric current conductive composition further containing a reducible metal compound, preferably an organic silver salt, a reducing agent, and having on different sides thereof an electrically conductive layer, with at least one of the electrically conductive layers being capable of transmitting actinic radiation. Image recording is accomplished by passing in the image recording element an image-wise pattern of an electric current sufficient to produce therein a storable latent image, followed by heating at least the electric current conductive composition layer to produce a visible image at the areas where the electric current passed through the electric current conductive composition.

Abstract: A novel toner system is provided employing a photodegradable toner. These toners are photodegradable during the fixing step in electrophotographic processes when they are exposed to light and then pressure or in the opposite sequences. This system provides excellent fixing of toner images at lower energy levels than is found in composition fixing systems.

Abstract: A method for developing electrostatic latent images comprises a first step of supplying uniformly a developer containing developing particles onto an electrostatic latent image carrying surface and a second step of supplying liquid onto the latent image carrying surface to remove any excess developer from the surface while leaving on the surface only such developing particles that are able to be retained as a result of the relative attraction between the developing particles and the electrostatic latent image so as to visualize the latent image. Apparatus for carrying out the method comprises a developing particle applying means and a liquid supplying means. The developing particle applying means is disposed to effect a uniform adhesion of developing particles onto an electrostatic latent image carrying surface.

Abstract: A conversion solution for zinc oxide coated electrophotographic master printing plates is provided containing triethylenetetramine or ethylenediamine which replaces the normally used ferrocyanide in conventional EP master conversions solutions.