US3404004A

US3404004A - Final soak bath for processed silver halide prints

Info

Publication number: US3404004A
Application number: US438050A
Authority: US
Inventors: Jean R Ake
Original assignee: Jean R. Ake
Current assignee: JEAN R AKE
Priority date: 1965-03-08
Filing date: 1965-03-08
Publication date: 1968-10-01
Anticipated expiration: 1985-10-01

Description

United States Patent No Drawing. Filed Mar. 8, 1965, Ser. No. 438,050

. 8 Claims. (CI. 9650) FINAL soAK This invention relates to photography, more particularly to a new rapid method of processing photographic materials, and solutions for use in the method. This invention relates to a new processing method, and final soak solutions, which greatly simplify conventional photographic processing methods by eliminating a plurality of tedious, time consuming, process steps, and the respective solutions used in each.

A conventional photographic plate consists of a large number of minute grains of crystalline silver halide suspended in a thin emulsion layer. When minute grains of a silver halide are affixed to a transparent support and exposed very briefly to light, no visible change is observed. However, the halide and support when immersed in a solution of a mild reducing agent, such as pyrogallic acid, the grains that have been exposed to light are developed that'is they are reduced to metallic silver much more rapidly than the unexposed grains. Apparently it is necessary for a quantum of energy to strike a sensitive spot in the crystal lattice of the grain in order that the silver halide may be reduced to give a nucleus of silver which then spreads, on further reduction, to include the full grain. When the photographic plate is developed, the grains of silver halide that are reduced by the developer appear as black metallic, silver, while the unreduced portion are unaffected. The unaffected grains are subsequently dissolved outwith sodium thiosulfate hypo, and the plate is washed'anddried. The bright parts of the image become the dark spotsonthe plate and the plate is thereafter called a negative. In printing, the plate is placed over a paper coated,with silver halide and exposed to lightf'The dark" spots on the negative absorb the light, whereas, the unaffected area permit light to pass through and acton the silver halide, producing a negative of the first negative. This double reversal produces a print in which the dark and light parts appear with the dark and light parts of the original object.

While the aforementioned photographic process is rela tively simple in principle, the actual processing operation of the plate and print is considerably more complex. It is old and standard in photographic processing to (1) place the exposed print or plate in the developer bath, whichis a solution of a mild reducing agent, (2) remove therefrom and stop development in normally an acetic acid bath, and (3) remove therefrom and place in a hypo'bath to fix the image. After this it is common and standard to go through an extensive and time consuming washing operation to remove all chemicals from the plate or print. 'This normally includes a hypo eliminator step, normally taking approximately three minutes, followed by immersion in a running water bath for twenty minutes to remove all chemicals used thus far in the processing. This is followed by another solution bath to provide for flattening the plate or print, followed by still another bath to provide for treatment prior to handling the plate orprint on an enlargingmachine generally, and in toning operations. The extensive and time consuming washing operations to remove chemicals from the plate or print following the immersing in the hypo bath normally takes approximately thirty minutes. The known processes require, after the hypo treatment, a minimum of four separate baths or solutions and the equipment to handle same. Very frequently, a small portion of the chemicals used to process the print or negative plate will remain on same and subsequently cause staining. This frequently occurs in spite of the tedious long washing and rinsing operations conventionally used in the art. Such chemical residue left on the plate is particularly objectionable when it is desired to further process a print by toning.

I have invented a new rapid process for producinga stable image in a photographic layer containing a latent image. The rapid process of my invention includes the steps of (1) developing the layer in the developing solution, (2) stopping the action of the developing solution, (3) fixing the resultant image in a stabilizing solution, and (4) treating the layer in a final soak bath to remove chemical residue. The final soak bath is an aqueous solution containing (1) a detergent agent, and (2) a water softening agent. A preferred specific embodiment of the final soak bath of my invention also includes a print flattening agent and a defoaming agent. Following the treating of the layer in the final soak bath the resultant image layer is rinsed in a bath.

The solution for rapid processing photographic layers of my invention is an aqueous solution containing a de tergent, and a Water softening agent. A preferred specific embodiment of my solution also includes a print flattening agent and a defoaming agent.

The new process of my invention for producing a stable visible image in a photographic layer containing a latent image solves many of the problems associated with developing processes known to the prior art. The new process of my invention eliminates the necessity for a large number of baths and solutions. This elimination reduces the washing time, and the effort necessary in developing and processing photographic layers. Further, the number of baths and solutions required to carry out the new process of my invention is decreased. This not only eliminates the necessity of a great deal of photographic processing equipment, but also materially decreases the amount of testing procedures to determine if the various solutions are usable. Another important advantage of the new process of my invention is that it very efiiciently and quickly removes all chemical residue from the prints and/ or plates. Consequently, the prints, negatives, etc. -developed by the new process of my invention will not develop stains and the like due to inefiicient removal of processing chemicals, and are therefore placed in perfect condition for further toning operationsand the like. Toning requires great purity in the condition of the prints to be toned.

An object of this invention is to provide a new rapid photographic processing method.

Another object of this invention is to provide a new photographic processing method wherein the photographic elements are completely cleared of chemical processing residue in a single soak solution.

Another object of this invention is to provide a new simplified photographic process that is simple to perform, and which requires a minimum of equipment.

Still another object of this invention is to provide a new final soak solution, particularly adapted for use in my process, which greatly simplifies photographic processing of prints, plates, X-rays, etc.

Yet another object of this invention is to provide a photographic processing method, and soak solution for use in the practice thereof wherein the photographic elements being processed are simultaneously thoroughly cleaned of chemical residue and are flattened in a single bath solution.

Other objects and advantages of the new processing method and final soak solutions of my invention will become apparent to those skilled in the art upon reading this disclosure.

The disclosure includes mention of specific components for use in the practice of my invention, and examples setting forth specific detailed illustrations of specific embodiments of my method and soak solutions. This disclosure should not be construed to unduly limit the scope of my invention.

In the new rapid process of my invention, the photographic print, X-ray, plates, negatives, or other photographic elements are placed in a developing solution. The photographic elements in general having a silver halide emulsion layer containing a latent image. The latent image is formed in the emulsion layer by exposure to light in a camera, enlarger, X-ray machine, or similar apparatus. The developer bath can be of any suitable type known to the prior, art, as for example a mild reducing agent such as pyrogallic acid. If the photographic elements are multilayer photographic film, paper, etc., used for color photography containing three or more selectively sensitive emulsion layers coated on a photographic support and possibly including color forming compounds or couplers, the developer bath or baths will be selected to develop the respective type of film or photographic element. After the photographic element has been removed from the developer bath, or baths, it is immersed in a solution for stopping the action of the developer solution. In process ing photographic elements having a silver halide emulsion layer the stop development solution can consist of an acetic acid bath. In developing color film, papers, and the like the proper solution for stopping the developing action can be selected by one skilled in the art. The photographic element is then placed in a stabilizing solution. This stabilizing solution can be of any suitable type, as for example sodium thiosulfate, in the processing of photographic elements having a silver halide emulsion layer. The aforedescribed processing steps are in general a portion of known developing processes and old in the art, but constitute a portion of the rapid process of my invention in combination with the following process steps.

The photographic element is subsequently immersed in a final soak bath to remove the chemical residue. The immersion in the final soak bath can be for any suitable period of time. However, I have found that a soaking time in the range of one second to four minutes, more preferably from one to three minutes, still more specifically approximately two minutes Works very well in the practice of my invention. The photographic elements are then washed in a moving rinsing water bath for a period in the range of two to eight minutes, preferably in the range of three to six minutes, still more preferably five minutes. The soaking time and the washing time will depend to a large extent on the Weight and thickness of the photographic element. The time in the final since bath will also depend to a certain extent on the number of elements in the bath, and on the efficiency of the washing apparatus used. The use of the final soak bath and the rinsing bath of my process very materially reduces the overall time of developing and processing photographic elements as compared to known developing processes. Further, the photographic elements are simultaneously cleaned and flattened by the use of the preferred specific embodiment of the final soak bath in my process. The process of my invention thoroughly cleans the photographic elements placing them in perfect condition for finishing operations such as toning and the like. The new process of my invention saves approximately ten to thirty minutes compared to conventional photographic processing known to the prior art, and does a more eflicient washing job with less expense and effort.

The final soak bath used in the process of my invention is an aqueous solution containing a detergent, a print flattening agent, a Water softening agent, and preferably a defoaming agent.

The detergent agent used in the final soak bath of my invention can be any suitable type of detergent. By a 4 detergent it is meant a compound having a molecule characterized as a relatively large hydro carbon molecule having from 7 to 18 carbon atoms, usually aliphatic or alkyl substituted aromatics in nature. One portion of the molecule is water soluble and possessed of relatively high polarity. This is the hydrophilic or solubilizing group. Typical solubilizing groups are -COOH, SO H, and SO NR Any suitable detergent can be used in the practice of my invention. Typical detergents are ammonium lauryl sulfate, sodium lauryl sulfate, potassium lauryl sulfate, alkylated aromatic sulfonic acids, alkyl sulfates, and the like. The most preferred detergent for use in the practice of my invention is ammonium lauryl sulfate sold under the trademark Sipon L22 by Alcolac Chemical Corporation. The detergent agent, preferably ammonium lauryl sulfate, can be used in any suitable concentration in the aqueous solution. However, I prefer to use the detergent in concentrations in the range of 0.002 to 0.02 gram per liter, more preferably 0.006 to 0.007 gram per liter.

Any suitable type of print flattening agent can be used in the final soak bath of my invention. Typical print flat tening agents are propylene glycol, hexylene glycol, ethylene glycol, glycerol and the like. I prefer the use of propylene glycol in the final soak bath of my invention. The print flattening agent, preferably propylene glycol, is used in the aqueous solution in any suitable concentration, preferably in the range of 2.6)(10- to 65 l0- gram moles per liter, more preferably 4.8 10 to 9.5 10 gram moles per liter.

Any suitable defoaming agent can be used in the final soak bath of my invention in any suitable concentration. Typical defoaming agents which can be used are 2- octanol, sulfonated oils, sulfonated silicones, mixtures thereof, and the like. The preferred defoaming agent for use in practice of my invention is 2-octanol. Another preferred defoaming agent is a sulfonated silicone mixture sold under the trademark Antifoam B by Dow Corning- Corporation. The defoaming agent, preferably 2-octanol, can be used in any suitable concentration, preferably in a concentration in the range of 0.7 l0 to 23x10- gram moles per liter, more preferably in the range of 2.7x 10- to 5.6 l0 gram moles per liter.

Any suitable water softening agent can be used in the practice of my invention in any suitable concentration. Typical examples of suitable water softening agents that can be used are sodium hexametaphosphate, sodium pyrophosphate, sodium tetraphosphate and the like and mixtures thereof. The preferred water softening agent for use in the water bath of my invention is hexametaphosphate, sold under the trademark Calgon by Calgon Corporation, and described in US. Patent No. 2,494,828. The water softening agent referably hexametaphosphate, can be used in any suitable concentration in the practice of my invention. Preferably the water softening agent is used in a concentration in the range of 0.01 to 0.15 gram per liter, more preferably in the range of 0.02 to 0.03 gram per liter, most preferably 0.022 gram per liter.

The following examples will serve to illustrate manner of practicing of my invention.

the

Example I TWo photographic plates, each having a single silver halide emulsion layer thereon, were exposed to produce a latent image thereon. The prints were then developed in a conventional silver halide developing solution. After the plates were removed from the developing solution, the developing action of the developing solution was stopped by immersing the plates in an acetic acid solution. The plates were then placed in a fixing solution consisting of a sodium thiosulfate hypo solution. Each of the prints was then Washed in a different Way, in the manner described in the following examples for purposes of comparison.

Example II The first print was then placed in a final soak bath for a period of two minutes. While in the bath the print was gently agitated. The bath was prepared by mixing the following ingredients to prepare a gallon of aqueous concentrate solution.

Sodium hexametaphosphate (Calgon-Calgon Corporation) 3.0

Four ounces of the concentrate solution was then combined with water to make a gallon of consumer concentrate. Four ounces of the consumer concentrate was then added to water to prepare a gallon of a final soak solution. The final soak solution was used to wash the prints. After the plate has been immersed in the final soak bath solution for a period of two minutes it was removed and rinsed in a moving water bath for a period of five minutes. Upon completion of the treatment the plate was found to be completely clear of processing chemicals, etc. and in perfect condition for further toning operation. Further the plate exhibited no apparent tendency to curl. The total elapsed time for performing the washing and rinsing operations described was seven minutes.

Example III For purposes of comparison the remaining plate prepared and developed in Example I was washed and rinsed in the conventional mtnner known to the prior art. The plate was first immersed in a conventional hypo or sodium thiosulfate eliminator solution for three minutes. Following this three minute immersion, the plate was placed in a wash bath for twenty minutes containing running water. The wash bath was intended to remove the hypo eliminator solution and the chemicals deposited on the plate in the operations performed in Example I. The plate was then placed in a conventional flattening solution bath for a period of three minutes. The plate was then removed from the flattening solution and placed in a bath to remove the flattening solution for a period of five minutes. The plate was then removed and compared with the plate processed in Example II. It was found that the plate processed in Example II in accordance with my invention was in better condition for toning operations due to the complete absence of chemicals, etc. and further showed less tendency to stain after drying. The total elapsed time for processing the plate in the conventional way was approximately thirty minutes.

The foregoing examples illustrate that the new rapid process of processing photographic prints of my invention takes considerably less time, and that very favorable results are obtained.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described herein and as defined in the appended claims.

I claim:

1. A rapid process for producing a stable visible image in a photographic silver halide emulsion layer containing a latent image comprising, developing said layer in a photographic silver halide developing solution, stopping the action of the developing solution by immersing the layer in an acetic acid solution, fixing the silver halide forming the resultant latent image by immersing the layer in a sodium thiosulfate solution, and subsequently treat ing the layer for a time interval in the range of one to three minutes in a final soak bath to remove the chemical residue, said final soak bath comprising, an aqueous solution containing ammonium lauryl sulfate in an amount in the range of 0.006 to 0.007 gram per liter, propylene glycol in an amount in the range of 4.8 X to 9.5 x l0 gram moles per liter, 2-octanol in an amount in the range of 2.7 10 to 5.6x 10- gram moles per liter, and sodium hexametaphosphate in an amount in the range of 0.02 to 0.03 gram per liter, and rinsing the resultant image layer in a moving water bath for a time interval in the range of four to seven minutes.

2. A rapid process for producing a stable visible image in a photographic silver halide emulsion layer containing a latent image comprising, developng said layer in a photographic developing solution, stopping the action of the developing solution by immersing the layer in a stop bath solution, fixing the layer forming the resultant latent image by immersing same in a stabilizng solution, and subsequently treating the layer for a time interval in the range of one-half to four minutes in a final soak bath to remove chemical residue, said final soak bath comprising, an aqueous solution containing ammonium lauryl sulfate in an amount in the range of 0.002 to 0.02 gram per liter, propylene glycol in the range of 2.6 10-' to 65 10 gram moles per liter, 2-octanol in an amount in the range of 0.7 10 to 23 l0- gram moles per liter, and sodium hexametaphosphate in an amount in the range of 0.01 to 0.15 gram per liter, and rinsing the resultant photographic image layer in a moving water bath for a time interval in the range of three to six minutes.

3. A rapid process for producing a stable visible image in a photographic silver halide emulsion layer containing a latent image comprising, developing said layer in a photographic developing solution, stopping the action of the developing solution by immersing the emulsion layer in a stop solution, fixing the resultant latent image by immersing the layer in a stabilizing solution, and subsequently treating the layer in a final soak bath to remove chemical residue for an interval in the range of one second to three minutes, said final soak bath comprising an aqueous solution containing an anionic synthetic detergent having a carbon chain length in the range of 7 to 18 carbon atoms per molecule and selected from the group consisting of ammonium lauryl sulfate, sodium lauryl sulfate, potassium lauryl sulfate, alkylated aromatic sulfonic acids, and mixtures thereof, in an amount in the range of 0.002 to 0.02 gram per liter, a print flattening agent selected from the group consisting of propylene glycol, hexylene glycol, ethylene glycol, glycerol and mixtures thereof in an amount in the range of 2.6 10* to 65 X10 gram moles per liter, a defoaming agent selected from the group consisting of methylhexacarbonyl, sulfonated oils, sulfonated silicones, and mixtures thereof, in an amount in the range of 0.7 10 to 23 10- gram moles per liter, and a water softening agent selected from the group consisting of sodium hexametaphosphate, sodium pyrophosphate, sodium tetraphosphate, and mixtures thereof, in an amount in the range of 0.01 to 0.15 gram per liter, and rinsing the resultant photographic image layer in a moving water bath for an interval in the range of one to ten minutes.

4. A rapid process for producing a stable visible image in a photographic silver halide emulsion layer containing a latent image comprising, developing said layer in a photographic developing solution, stopping the ac-' tion of the developing solution by immersing the emulsion layer in a stop solution, fixing the latent image by immersing the layer in a stabilizing solution, and subsequently treating the layer in a final soak bath to remove chemical residue, said final soak bath comprising, an aqueous solution containing an anionic synthetic detergent having a carbon link in the range of 7 to 18 carbon atoms per molecule ad selected from the group consisting of ammonium lauryl sulfate, sodium lauryl sulfate, potassium lauryl sulfate, alkylated aromatic sulfonic acids, and mixtures thereof in an amount in the range of 0.006 to 0.007 gram per liter, a print flattening compound selected from the group consisting of propylene glycol, ethylene glycol, hexylene glycol, glycerol and mixtures thereof in an amount in the range of 4.8 10 to 9.5 10- gram moles per liter, a defoaming agent selected from the group consisting of methylhexacarbonyl, sulfonated oils, sulfonated silicones, and mixtures thereof in an amount in the range of 2.7 to 5.6 10- gram moles per liter, and a water softening agent selected from the group consisting of sodium hexametaphosphate, sodium pyrophosphate, sodium tetraphosphate, and mixtures thereof 0.02 to 0.03 gram per liter, and rinsing the resultant photographic image layer in a Water bath.

5. A rapid process for producing a stable visible image in a photographic silver halide layer containing a latent image comprising, developing said layer in a photographic developing solution, stopping the action of the developing solution by immersing said layer in a stop solution, fixing the resultant latent image by immersing the layer in a stabilizing solution, and subsequently treating the layer in a final soak bath to remove chemical residue, said final soak bath comprising, a detergent compound selected from the group consisting of ammonium lauryl sulfate, sodium lauryl sulfate, potassium lauryl sulfate, alkylated aromatic sulfonic acids and mixtures thereof in an amount in the range of 0.002 to 0.02 gram per liter, a print fiattening agent selected from the group consisting of propylene glycol, hexylene glycol, glycerol and mixtures thereof in an amount in the range of 2.6 10- to 65x10- gram moles per liter, and a water softening agent selected from the group consisting of sodium hexametaphosphate, sodium tetraphosphate, sodium pyrophosphate, and mixtures thereof in an amount in the range of 0.01 to 0.15 gram per liter, and rinsing the resultant photographic image layer in a liquid bath.

6. A rapid process for producing a stable image in a photographic silver halide layer containing a latent image comprising, developing said layer in a developing solution, stopping the action of the developing solution, fixing the resultant latent image in a stabilizing solution, and subsequently treating the layer in a final soak bath to remove chemical residue, said final soak bath comprising, an aqueous solution containing (1) a detergent agent selected from the group consisting of ammonium lauryl sulfate, sodium lauryl sulfate, potassium lauryl sulfate, alkylated aromatic sulfonic acids, and mixtures thereof, in an amount in the range of 0.006 to 0.007 gram per liter, a print flattening agent selected from the group consisting of propylene glycol, hexylene glycol, ethylene glycol, glycerol, and mixtures thereof, in an amount in the range of 4.8 10- to 9.5 x 10- gram moles per liter, and a water softening agent selected from the group consisting of sodium hexametaphosphate, sodium tetraphosphate, sodium pryophosphate, and mixtures thereof, in an amount in the range of 0.02 to 0.03 gram per liter, and rinsing the resultant image layer in a water bath.

7. A final soak solution to remove chemical residue for use in photographic processes for developing a stable image in a photographic silver halide emulsion layer comprising, an aqueous solution containing ammonium lauryl sulfate in an amount in the range of 0.006 to 0.007 gram per liter, propylene glycol in an amount in the range of 4.8 10 to 9.5 x 10- gram moles per liter, 2-octanol in an amount in the range of 2.7 X l0 to 5.6 10 gram moles per liter, and sodium hexametaphosphate in an amount in the range of 0.02 to 0.03 gram per liter.

8. A final soak bath to remove chemical residue in photographic processes for producing a stable visible image on a photographic silver halide emulsion layer comprising, an aqueous solution containing a detergent selected from the group consisting of ammonium lauryl sulfate, sodium lauryl sulfate, and mixtures thereof, in an amount in the range of 0.002 to 0.02 gram per liter, a print flattening agent selected from the group consisting of propylene glycol, hexylene glycol, ethylene glycol, glycerol, and mixtures thereof in an amount in the range of 2.6)(10 to 10 gram moles per liter, a defoaming agent selected from the group consisting of methylhexacarbonyl, sulfonated oils, sulfonated silicones, and mixtures thereof in an amount in the range of 0.7)(10 to 23 10* gram moles per liter, and a water softening agent selected from the group consisting of sodium hexametaphosphate, sodium pyrophosphate, sodium tetraphosphate, and mixtures thereof, in an amount in the range of 0.01 to 0.15 gram per liter.

References Cited UNITED STATES PATENTS 2,367,516 1/1945 Muehler et a1. 9650 2,541,470 2/1951 Henn et a1. 9666 2,556,540 6/1951 Henn et al. 965O 2,943,058 6/ 1960 Cook.

OTHER REFERENCES Glafkides, P.: Photographic Chemistry, London, Fountain Press, 1958, vol. 1, p. 148. TR 210.65.

The Condensed Chemical Dictionary, New York, Reinhold Publishing Corporation, sixth edition, 1961, pp. 344, 823, 1090, 1224. QDS. C5.

NORMAN G. TORCHIN, Primary Examiner.

C. E. DAVIS, Assistant Examiner.

Claims

3. A RAPID PROCESS FOR PRODUCING A STABLE VISIBLE IMAGE IN A PHOTOGRAPHIC SILVER HALIDE EMULSION LAYER CONTAINING A LATENT IMAGE COMPRISING, DEVELOPING SAID LAYER IN A PHOTOGRAPHIC DEVELOPING SOLUTION, STOPPING THE ACTION OF THE DEVELOPING SOLUTION BY IMMERSING THE EMULSION LAYER IN A STOP SOLUTION, FIXING THE RESULTANT LATENT IMAGE BY IMMERSING THE LAYER IN A STABILIZING SOLUTION, AND SUBSEQUENTLY TREATING THE LAYER IN A FINAL SOAK BATH TO REMOVE CHEMICAL RESIDUE FOR AN INTERVAL IN THE RANGE OF ONE SECOND TO THREE MINUTES, SAID FINAL SOAK BATH COMPRISING AN AQUEOUS SOLUTION CONTAINING AN ANIONIC SYNTHETIC DETERGENT HAVING A CARBON CHAIN LENGTH IN THE RANGE OF 7 TO 18 CARBON ATOMS PER MOLECULE AND SELECTED FROM THE GROUP CONSISTING OF AMMONIUM LAURYL SULFATE, SODIUM LAURYL SULFATE, POTASSIUM LAURYL SULFATE, ALKYLATED AROMATIC SULFONIC ACIDS, AND MIXTURES THEREOF, IN AN AMOUNT IN THE RANGE OF 0.002 TO 0.02 GRAM PER LITER, A PRINT FLATTENING AGENT SELECTED FROM THE GROUP CONSISTING OF PROPYLENE GLYCOL, HEXYLENE GLYCOL, ETHYLENE GLYCOL, GLYCEROL AND MIXTURES THEREOF IN AN AMOUNT IN THE RANGE OF 2.6X10-6 TO 65X10-6 GRAM MOLES PER LITER, A DEFOAMING AGENT SELECTED FROM THE GROUP CONSISTING OF METHYLHEXACARBONYL, SULFONATED OILS, SULFONATED SILICONES, AND MIXTURES THEREOF, IN AN AMOUNT IN THE RANGE OF 0.7X10-6 TO 23X10-6 GRAM MOLES PER LITER, AND A WATER SOFTENING AGENT SELECTED FROM THE GROUP CONSISTING OF SODIUM HEXAMETAPHOSPHATE, SODIUM PYROPHOSPHATE, SODIUM TETRAPHOSPHATE, AND MIXTURES THEREOF, IN AN AMOUNT IN THE RANGE OF 0.01 TO 0.15 GRAM PER LITER, AND RINSING THE RESULTANT PHOTOGRAPHIC IMAGE LAYER IN A MOVING WATER BATH FOR AN INTERVAL IN THE RANGE OF ONE TO TEN MINUTES.