Abstract: Use in the treatment of ceramic materials for obtaining an easy stain removal, of mono- and bifunctional (per)fluoropolyether derivatives having the following structures: [Rf—CFY-L-O]mP(O)(O?Z+)3-m??(A) (O?Z+)2P(O)[O-L-YFC—O—Rf—CFY-L-O—P(O)(O?Z+)]m?-[O-L-YFC—O—Rf—CFY-L-O]P(O)(O?Z+)2??(B) Rf—CFY-L-W??(C) W-L-YFC—O—Rf—CFY-L-W??(D) wherein m? is an integer from 0 to 20, preferably from 0 to 4; L is an organic group selected from —CH2-(OCH2CH2)n—, —CO—NR?—(CH2)q—, with R?=H or C1–C4 alkyl group; n=0–8, preferably 1–3, q=1–8, preferably 1–3; Z=H, alkaline metal or NR4 group with R=H or C1–C4 alkyl group; Y=F, CF3; m=1,2,3, preferably 1,2; W is a —Si(R1)?(OR2)3-? group with ?=0,1,2, R1 and R2 equal to or different from each other are C1–C6 alkyl groups, optionally containing one or more ether O, C6–C10 aryl groups, C7–C12 alkyl-aryl or aryl-alkyl groups.

Abstract: This invention relates to a method to facilitate the removal of adherent polymeric films from a hard surface occasioned by the evaporation of solvent from compositions containing an anionic amphiphilic polymer, the method comprising incorporating a phosphate ester surfactant into the compositions, and washing the film from the surface to which it adheres.

Abstract: A coherent body (B) of wet crushed ice is pumped along a pipe (5). The crushed ice body can be used as a means of cleaning the pipe wall, as a means of driving a product liquid out of the pipe for recovery, or as a barrier for preventing mixing of two different bodies of liquid (1,2) in the pipe to either side of it. Being coherent but flowable and non-tensile, the mass of crushed ice can negotiate internal constrictions, obstructions and junctions of the pipe readily, unlike conventional solid or gelled pigs.

Abstract: An improved method for removing contaminant particles from a surface of a semiconductor wafer includes forming a sacrificial film on the surface of the wafer and then removing the sacrificial film by supercritical fluid cleaning. The removal of the sacrificial film via the supercritical fluid cleaning process facilitates removing the contaminant particles. The method further includes identifying and characterizing the contaminant particles and creating a record of the contaminant particle data. The composition of the sacrificial film is selected based on the contaminant particles data and the supercritical cleaning recipe is selected based on the composition of the sacrificial film and the contaminant particles data.

Abstract: Powdered compositions comprising in admixture inorganic salts and silica gel, and optionally a fragrance additive, are disclosed. The novel compositions are useful in absorbing and deodorizing liquid waste and for removing such waste from irregular surfaces, such as textiles and carpeting, as well as from smooth hard surfaces. The compositions are effective in absorbing liquid biohazards, such as blood, vomit, urine, and other body fluids. For this application, a halogen-containing compound, such as sodium hypochlorite or calcium hypochlorite is preferably included in the composition. The mixtures can also be utilized for the absorption of oil-based spills and hydrocarbons and are also effective in removing moisture and malodors associated with pet urine and other moisture-related stains encountered in the home. When applied to liquid wastes, the absorbent properties of the compositions contain the spill, creating a solid cohesive matrix that allows for easy disposal.

Abstract: The foreign matter adhered to the data bearing surface of a master medium is removed by use of a dry, non-contact removal process, so as to facilitate the performance of a high transfer quality magnetic transfer. Before performing a magnetic transfer or forming an optical disk, a magnetic transfer master medium or an optical disk master medium is placed in a vacuum chamber. The vacuum chamber is evacuated by an evacuating means, and a reactive gas is introduced thereto by a gas introducing means. In the state in which the chamber has been evacuated and the reactive gas has been introduced thereto, a discharging means applies a discharge voltage in the chamber, causing a plasma discharge to be generated between the master medium and an electrode. The plasma etching action of the plasma discharge burns off the foreign matter adhered to the surface of the master medium.

Abstract: An apparatus and method is provided for processing an electronic device, particularly the molding and cleaning of the device. Molding means encapsulate the electronic device with a molding compound. Thereafter, stain from one or more surfaces of the electronic device is removed by a stain removal device adapted to impact the electronic device with a polishing agent. A residue removal system then removes residue from the one or more surfaces of the electronic device.

Abstract: There is provided a surface cleaning apparatus and method using plasma to remove a native oxide layer, a chemical oxide layer, and a damaged portion from a silicon substrate surface, and contaminants from a metal surface. By absorbing potential in a grounded grid or baffle between a plasma generator and a substrate, only radicals are passed to the substrate, and HF gas is used as a second processing gas. Thus a native oxide layer, a chemical oxide layer, or a damaged portion formed on the silicon substrate during etching a contact hole is removed and the environment of a chamber is maintained constant by introducing a conditioning gas after each wafer process. Therefore, process uniformity is improved.

Abstract: A method of cleaning a printhead in an inkjet printer by removing organic debris deposits from the printhead, uses anyone of the liquid mixes of NaOCl (sodium hypochlorite) and H2O (water), H2O2 (hydrogen peroxide) and H2O, Na2S2O4 (sodium hydrosulfite) and H2O, CaCl2O2 (calcium hypochlorite) and H2O, or KMnO4 (potassium permanganate) and H2O on the debris deposits, to serve as a cleaning agent.

Abstract: A method of cleaning a printhead in an inkjet printer by removing organic debris deposits from the printhead, uses anyone of the liquid mixes of NaOCl (sodium hypochlorite) and H2O (water), H2O2 (hydrogen peroxide) and H2O, Na2S2O4 (sodium hydrosulfite) and H2O, CaCl2O2 (calcium hypochlorite) and H2O, or KMnO4 (potassium pernanganate) and H2O on the debris deposits, to serve as a cleaning agent.

Abstract: This invention relates to a process for cleaning surfaces, notably metal surfaces.

Abstract: Contaminants are removed from a surface of a substrate by applying a fluid to the surface; lowering the temperature of the fluid to form a solid layer of the fluid and entrap contaminants therein; and applying energy to the layer and/or substrate to cause the layer containing the contaminants to separate from the surface.

Abstract: An apparatus and method are provided for removing contaminate particulate matter from substrate surfaces such as semiconductor wafers. The method and apparatus use a material, preferably a liquid curable polymer, which is applied as a sacrificial coating to the surface of a substrate containing contaminate particulate matter thereon. An energy source is used to dislodge the contaminate particulate matter from the surface of the wafer into the sacrificial coating so that the particles are partially or fully encapsulated and suspended in the sacrificial coating. The sacrificial coating is then removed. The coating is preferably formed into a film to facilitate removal of the coating by pulling (stripping) the film providing a cleaner substrate surface.

Abstract: A method for cleaning cookware and tableware with film-forming liquid dishwashing compositions is disclosed. The method includes the steps of applying the composition to soiled cookware/tableware, allowing the composition to form a film and act on the soil, and removing the film with the soil, leaving a clean surface. The compositions include a film-forming polymer, a plasticizer, a cleaning active and a carrier.

Abstract: A cleaning sheet with frame for cleaning a molding die comprising a cleaning heat main body that covers the entire mating surface of a molding die and a reinforcing frame which can be disposed along the peripheral edge to the outside of the plural cavities of the mating surface of the molding die, the cleaning sheet main body being formed with first through holes at positions corresponding to the cavities of the molding die, air vent slits and flow cavity recesses at positions corresponding to the air vents of the cavities, second through holes at positions corresponding to the pots of the molding die, and slits at positions corresponding to the runners of the molding die, thereby capable of improving the cleaning effect of the molding die and shortening the time for the cleaning operation to improve the productivity.

Abstract: An improved method for removing contaminant particles from a surface of a semiconductor wafer includes forming a sacrificial film on the surface of the wafer and then removing the sacrificial film by supercritical fluid cleaning. The removal of the sacrificial film via the supercritical fluid cleaning process facilitates removing the contaminant particles. The method further includes identifying and characterizing the contaminant particles and creating a record of the contaminant particle data. The composition of the sacrificial film is selected based on the contaminant particles data and the supercritical cleaning recipe is selected based on the composition of the sacrificial film and the contaminant particles data.

Abstract: The present invention relates to anaerobic curing impregnation sealant compositions which are readily separable from water upon mixing.

Abstract: A method and apparatus are provided for removing solid and/or liquid residues from electronic components such as semiconductor wafers utilizing liquid or supercritical carbon dioxide which is solidified on the surface of the wafer and then vaporized and removed from the system. In a preferred embodiment the solidification and vaporizing steps are repeated (cycled) before removal of the CO2 from the vessel. The residues are carried away with the vaporized carbon dioxide.

Abstract: At least one part of a road surface is covered by a photocatalyst layer containing a photocatalyst such as titanium dioxide, etc. to purify pollutants in exhaust gases emitted from vehicles by photocatalytic reaction of the photocatalyst. Pollutant-originating matters as retained on the photocatalyst layer are washed away by rain water or sprinkled water. In one embodiment of the invention, road 12 is a road provided with a dewaterable pavement and rain water passes through surface layer 18 during raining, flows over and along base layer 16 and is discharged. In surface layer 18, numerous aggregates of small particle sizes 1802 are projected from the entire surface of concrete layer 1804. Titanium dioxide layer 20 is formed by injecting or spraying a mixture comprising titanium dioxide, cement, a filler and water onto the entire surface of surface layer 18 thinly and is water-permeable.

Abstract: A glass article comprising a glass body having a surface and a water-soluble surface-protection film formed on the surface. The water-soluble surface-protection film is made of hydroxy acid or salt thereof. The hydroxy acid or the salt thereof is one or more kinds selected from the group consisting of citric acid, tartaric acid, malic acid, gluconic acid and salts thereof. An example of the glass body is a funnel part having an anode button for a CRT.

Abstract: A method for the production of a glass substrate for magnetic recording mediums is herein provided and this method is characterized in that the final cleaning step is performed in two stages, in which scrubbing and dip-cleaning steps are carried out after the completion of the first cleaning stage and after the growth of needle-like projections comprising an alkali metal carbonate on the surface of the glass substrate. The method for the production of a glass substrate for magnetic recording mediums does not require the use of an expensive device having high resistance to acids. Moreover, in the glass substrate for magnetic recording mediums produced by the foregoing method, any growth of needle-like projections containing an alkali metal carbonate on the surface of the glass substrate is inhibited even during temporal storage of the substrate.

Abstract: Many prior art processes for cleaning predominantly organic hard surfaces have been found to be considerably less effective in removing very fine particles on such surfaces than are the best cleaners for metallic surfaces. However, it has been found, and forms the basis of this invention, that fine particles can be removed effectively from organic surfaces by an indirect process of first forming a thin solid coating over the surface and then removing the solid coating, into which the fine particles that formerly contaminated the surface to be cleaned have presumably become incorporated. Substantially hydrolyzed poly(vinyl acetate) has been found particularly useful for forming the thin solid coating when this coating is to be removed by treatment with an acidic aqueous solution; acrylate polymers are preferred if the solid coating is to be removed by an alkaline aqueous solution.

Abstract: Cleaning compositions including a photocatalytic material and a sensitiser employ a photocatalytic material and a sensitiser at a locus, for example on a surface. The residue combats soils and/or undesired microorganisms at the locus.

Abstract: A method for using a monitor substrate to determine effectiveness of a cleaning operation is provided. The method includes selecting a substrate from a lot of substrates and inspecting a surface of the substrate to determine a roughness profile of the substrate. The monitor substrate is then processed through a cleaning operation, and the monitor substrate is patterned with die regions throughout. Each of the die regions has a plurality of areas defining distinct roughness simulations. The method the proceeds to inspecting the monitor substrate at one die region and at one of the plurality of areas in the one die region that most closely resembles the roughness profile of the substrate. The inspecting of the monitor substrate is configured to yield data regarding cleaning performance of the cleaning operation.

Abstract: A cured resin dissolving composition comprising an alkyl ammonium fluoride dissolved in a wide variety of solvents and co-solvents with a soluble amine and surfactant. The composition is ionized to release fluoride which penetrates and reacts with the cured resin causing bond cleavage, breakdown, and dissolution of polymeric structure. The solvent system may be composed of hydrophilic solvents such as amides, ketones, alcohols, esters, and ethers, as well as hydrophobic families such as alkanes, alkenes, halogenated hydrocarbons, and aromatic hydrocarbons of varying carbon chain length and molecular weight. The rate of reactivity of polymer breakdown is concentration dependent upon ionized fluoride, stimulated by solution polarity and upon the amine triggered release from the organo-fluoirde. This rate is determined to be optimum in hydrophilic solvent systems with an amine. The product may be used in manufacturing to remove unwanted cured resins and their residues.

Abstract: Embodiments of the present invention include a method of depositing an improved seasoning film. In one embodiment the method includes, prior to performing a substrate processing operation, forming a layer of silicon over an interior surface of the substrate processing chamber as opposed to a layer of silicon oxide. In certain embodiments, the layer of silicon comprises at least 70% atomic silicon, is deposited from a high density silane (SinH2n+2) process gas and/or is deposited from a plasma having a density of at least 1×1011 ions/cm3.

Abstract: Process for enhancing the cleaning properties of an aqueous cleaning composition comprising at least one surfactant, intended for cleaning a surface which has been soiled with soiling, by adding to said cleaning composition, at least one polymer (P) comprising:

Abstract: Process for pickling stainless steel carried out at a temperature of between 20° and 70° C., with the use of a pickling solution containing the following basic ingredients: H2SO4 (free acid): 50 to 200 g/l HF (free acid): 0 to 60 g/l F− anion (total): 5 to 150 g/l SO42− anion (total): 50 to 350 g/l Total free acidity (H2SO4+HF): between 1 and 7 g. equiv./l where by “free acid” is meant the acid that does not constitute the anion bound in the form of salts or complexes with the metal cations present in the solution; and, in addition: Fe3+ in a quantity of at least 15 g/l chloride anion in a quantity of between 0.1 and 10 g/l, into which solution is fed, during the pickling process, an oxidant that is able to oxidize Fe2+ to Fe3+ in order to maintain the redox potential of the solution at a value of between +230 and +800 mV.

Abstract: This method of prevention of particle pollution in a pre-clean chamber includes an oxygen gas supplying step for injecting oxygen gas into the pre-clean chamber; and a plasma generating step for ionizing the oxygen gas into plasma so as to interact with silicon-rich oxide to form a silicon oxide layer in the pre-clean chamber. The method according to the invention could prevent particle pollution due to peeling-off of silicon-rich oxide in a pre-clean chamber so as to prolong the life of a bell-jar therein.

Abstract: A cleaning substrate for cleaning and regenerating a mold is disclosed. The mold is contaminated after repeatedly packaging the semiconductor device by making use of thermosetting resin. At least a protrusion of the substrate can substantially match with and be contained within the edges of the mold cavity of the mold when the cleaning substrate is placed in the mold.

Abstract: A new method is provided to clean melamine deposits from tools and components that are used to form molds around and to therewith encapsulate BGA devices. The cleaning process applies a dummy BGA substrate as part of and during the cleaning procedure. This dummy BGA substrate replaces the conventionally used copper strips that shield areas of the molding tools during the cleaning cycle. The dummy copper strips require, during and as part of the melamine cleaning process, frequent cleaning, which adds considerable to the time and expense of the melamine cleaning process.

Abstract: Contaminants are removed from a surface of a substrate by applying a fluid to the surface; lowering the temperature of the fluid to form a solid layer of the fluid and entrap contaminants therein; and applying energy to the layer and/or substrate to cause the layer containing the contaminants to separate from the surface.

Abstract: An apparatus and method are provided for removing contaminate particulate matter from substrate surfaces such as semiconductor wafers. The method and apparatus use a material, preferably a liquid curable polymer, which is applied as a sacrificial coating to the surface of a substrate containing contaminate particulate matter thereon. An energy source is used to dislodge the contaminate particulate matter from the surface of the wafer into the sacrificial coating so that the particles are partially or fully encapsulated and suspended in the sacrificial coating. The sacrificial coating is then removed. The coating is preferably formed into a film to facilitate removal of the coating by pulling (stripping) the film providing a cleaner substrate surface.

Abstract: A new method is provided to clean melamine deposits from tools and components that are used to form molds around and to therewith encapsulate BGA devices. The cleaning process applies a dummy BGA substrate as part of and during the cleaning procedure. This dummy BGA substrate replaces the conventionally used copper strips that shield areas of the molding tools during the cleaning cycle. The dummy copper strips require, during and as part of the melamine cleaning process, frequent cleaning, which adds considerable to the time and expense of the melamine cleaning process.

Abstract: A portable, diver-operated cryogenic freezing unit cleans surfaces underwater. A housing has a first chamber that contains cryogenic liquid, such as liquid nitrogen, and a second chamber is disposed adjacent to an end portion that fits about contaminating matter on a surface underwater. A valve vents cryogenic liquid from the first chamber to expand as gas in the second chamber. The vented cryogenic liquid and gas freeze a slug of water and the contaminating matter on the surface within the end portion. The housing is bent, twisted or otherwise displaced to break or pry-away and remove the frozen slug of water and contaminating matter from the surface to thereby clean it. A method of cleaning a surface underwater using the cryogenic freezing unit is described.

Abstract: In the preparation of esters of acrylic or methacrylic acid by esterification with alcohols, the interfering deposits formed on the apparatus parts by relatively high molecular weight by-products can be avoided, removed or lessened by allowing a liquid partly or wholly consisting of the alcohol used for the esterification to act on the deposits, fouled apparatus parts or on the surfaces of the apparatus parts on which deposits are easily formed, with preference being given to wetting the deposits or surfaces using suitable nozzles or cleaning sprayers.

Abstract: A portable, diver-operated cryogenic freezing unit cleans surfaces underwater. A housing has a first chamber that contains cryogenic liquid, such as liquid nitrogen, and a second chamber is disposed adjacent to an end portion that fits about contaminating matter on a surface underwater. A valve vents cryogenic liquid from the first chamber to expand as gas in the second chamber. The vented cryogenic liquid and gas freeze a slug of water and the contaminating matter on the surface within the end portion. The housing is bent, twisted or otherwise displaced to break or pry-away and remove the frozen slug of water and contaminating matter from the surface to thereby clean it. A method of cleaning a surface underwater using the cryogenic freezing unit is described.

Abstract: An article having a metallic surface treated with polymeric complexing agent is described. Particularly suitable polymeric complexing agents are phosphonoalkylated polyethyleneimines and/or carboxyalkylated polyethyleneimines and/or vinylimidazole polymers. As a rule, the treated metallic surface forms the total inner surface or a part of the inner surface of a process apparatus or of a container. The surface is protected by the treatment, in particular from the adhesion of polymer.

Abstract: Powdered compositions comprising in admixture inorganic salts and silica gel, and optionally a fragrance additive, are disclosed. The novel compositions are useful in absorbing and deodorizing liquid waste and for removing such waste from irregular surfaces, such as textiles and carpeting, as well as from smooth hard surfaces. The compositions are effective in absorbing liquid biohazards, such as blood, vomit, urine, and other body fluids. For this application, a halogen-containing compound, such as sodium hypochlorite or calcium hypochlorite is preferably included in the composition. The mixtures can also be utilized for the absorption of oil-based spills and hydrocarbons and are also effective in removing moisture and malodors associated with pet urine and other moisture-related stains encountered in the home. When applied to liquid wastes, the absorbent properties of the compositions contain the spill, creating a solid cohesive matrix that allows for easy disposal.

Abstract: A method for cleaning phosphorus from a MBE vacuum chamber by freezing the panel (22) placed within the vacuum chamber (10) onto which excess phosphorus is deposited. The panel is connected to a source of cold nitrogen (24) which cools the panel. Water is introduced after the panels are cooled so as to form a layer of ice on top of the phosphorus. The panel may then be removed for cleaning with ice covering the phosphorus without danger of ignition of the phosphorus.

Abstract: A paint stripper for use by immersion of a painted substrate in a bath of the composition or application in place has two phases, one aqueous and the other of partially water soluble organic solvent. The aqueous phase is saturated with organic solvent. The organic solvent is preferably benzyl alcohol, dibasic ester or ethyl-e-ethoxypropionate, The total amount of organic solvent in the bath is suitably in the range 2 to 20%. The stripper may be acid or alkali activated. The application stripper is thickened to avoid separation during storage.

Abstract: A method for removing products of hot corrosion and oxidation from selective portions of surfaces of a gas turbine engine, such as coatings and substrates, following exposure of the surfaces to hot oxidative gases of the turbine exhaust. The method involves a high temperature chemical reaction and has no detrimental effect on adjacent coatings and substrates that have not been attacked by the hot exhaust gases.

Abstract: A self-cleaning automotive head lamp, wherein the inner surface of the lens has applied to it an amphiphilic coating containing a photocatalyst.

Abstract: An in-situ method for regenerating a chemical-mechanical polishing pad which includes the steps of: forming the polishing pad by dispensing liquid moldable material, such as wax, polymers or water, on a polishing surface and solidifying the liquid material by reducing the temperature, allowing the moldable material to harden; distributing slurry material on the polishing pad; polishing the surface of a semiconductor wafer with a combination of the slurry material and the polishing pad; and regenerating in-situ the polishing pad. This method quickly, easily and repeatably, resurfaces and refreshes the surface on which the a semiconductor wafer is polished. The polishing pad may also include abrasives embedded therein to enhance its polishing capabilities.

Abstract: A method is disclosed for removing impurities from an elastomer intended for medical or pharmaceutical use, which includes a step of performing a first solvent extraction process on the elastomer by contacting the elastomer with a first extracting solvent in a non-supercritical state to substantially remove impurities from the elastomer, thereby leaving a residue of said first extracting solvent in the elastomer. The elastomer is there after subjected to a second solvent extraction process, by contacting the elastomer with a second extracting solvent, which is a supercritical fluid or a mixture of super critical fluids, in order to remove substantially reduce the concentration of the residue of the first extracting solvent remaining in the elastomer after the first solvent extraction process.

Abstract: A graffiti removing method including the steps of: applying a solvent condensation type silicone resin coating composition having water repellency onto a surface of a base material of a structure through a primer layer to form an adhesion-resistant surface layer on the primer layer; applying a releasable coating composition onto the surface layer to form a releasable layer, after graffiti are written onto the surface layer; and releasing the releasable layer from the surface layer after the releasable layer is hardened to thereby remove the graffiti together with the releasable layer from a surface of the surface layer, whereby although graffiti remaining on a surface layer are generally removed by wiping, or the like, not only it is difficult to wipe off graffiti but also the surface layer may be injured.

Abstract: A method for cleaning structural surface 1 by forming a substratum membrane 17a thereon through application and drying of a thin layer 16 of aqueous solution 5 of membrane-forming polymer 2 on a structural surface, spreading a fibrous reinforcing member 15 on the thin layer 16 before drying or the substratum membrane 17a after dried, and applying the aqueous solution 5 on the outer surface of the reinforcing member 15 while wetting it in such a manner that, upon drying, an overlying membrane 17b integral with both the substratum membrane 17a and the reinforcing member 15 is formed so as to generate a multi-layer membrane 18 having the substratum and overlying membranes sandwiching the reinforcing member. After causing foreign matters on the structural surface 1 to adhere onto the substratum membrane 17a, the multi-layer membrane 18 is peeled off from the structural surface 1.

Abstract: Electrostatic discharges that occur during solid CO.sub.2 cleaning of a substrate (10) can be virtually eliminated by chilling the substrate so that moisture in the atmosphere, in the form of water droplets(30), condense on the substrate surface (14), thereby forming a continuous film of water (28). The water in the film (28) reacts with the solid CO.sub.2 (24) to form carbonic acid that dissociates into free ions that neutralize the charge on the solid CO.sub.2.

Abstract: Processes for immobilizing solid contaminated materials, such as radioactive species, hazardous species, or combinations of both radioactive and hazardous species, comprise mixing the contaminated materials with hydrated ferric oxides, and then pressing the mixture at a temperature of at least about 150.degree. C. and gradually removing a large part of the water while under pressure to produce a solid composition. The water content of the mixture is adjusted if necessary. Contaminated materials dissolved or suspended in an aqueous solution can be immobilized by precipitating hydrated ferric oxide in the solution, and adjusting the water content and pressing, as above. In another process in accordance with the present invention, hydrated ferric oxides are deposited on metal surfaces. The deposited ferric oxide is pressed to produce a solid coating adhered to the surface, to retard corrosion. A ceramic body of ferric oxide composition may also be made in accordance with the present invention.

Abstract: Process for stainless steel pickling consisting in placing the material to be treated in a bath kept at a temperature ranging from 30.degree. C. to 70.degree. C. and containing:a) HClb) Fe.sup.3+c) HFd) emulsifiers, wetting agents, polishing agents, acid attack inhibitors;the bath being fed continuously with:an air flow equal to at least 3 m.sup.3 /h per m.sup.3 bath min. and an oxidizer quantity adjusted to the bath redox potential to be kept at 250 mV min.