US2629661A - Antifading baths for photographic black and white materials - Google Patents
Antifading baths for photographic black and white materials Download PDFInfo
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- US2629661A US2629661A US252808A US25280851A US2629661A US 2629661 A US2629661 A US 2629661A US 252808 A US252808 A US 252808A US 25280851 A US25280851 A US 25280851A US 2629661 A US2629661 A US 2629661A
- Authority
- US
- United States
- Prior art keywords
- black
- baths
- antifading
- white
- silver
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000000463 material Substances 0.000 title description 8
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims description 21
- 229910052709 silver Inorganic materials 0.000 claims description 20
- 239000004332 silver Substances 0.000 claims description 20
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 15
- 239000000839 emulsion Substances 0.000 claims description 11
- -1 SILVER HALIDE Chemical class 0.000 claims description 9
- 238000005562 fading Methods 0.000 claims description 9
- 230000008859 change Effects 0.000 claims description 8
- 239000007864 aqueous solution Substances 0.000 claims description 5
- 239000004202 carbamide Substances 0.000 claims description 5
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 4
- 238000000034 method Methods 0.000 claims description 4
- 230000006872 improvement Effects 0.000 claims description 2
- 230000008569 process Effects 0.000 claims description 2
- 239000000047 product Substances 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- 235000013877 carbamide Nutrition 0.000 description 6
- 239000000243 solution Substances 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- QUBQYFYWUJJAAK-UHFFFAOYSA-N oxymethurea Chemical compound OCNC(=O)NCO QUBQYFYWUJJAAK-UHFFFAOYSA-N 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical class S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- QIGBRXMKCJKVMJ-UHFFFAOYSA-N Hydroquinone Chemical compound OC1=CC=C(O)C=C1 QIGBRXMKCJKVMJ-UHFFFAOYSA-N 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- 125000000217 alkyl group Chemical group 0.000 description 2
- CODNYICXDISAEA-UHFFFAOYSA-N bromine monochloride Chemical compound BrCl CODNYICXDISAEA-UHFFFAOYSA-N 0.000 description 2
- 239000007859 condensation product Substances 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- XMYQHJDBLRZMLW-UHFFFAOYSA-N methanolamine Chemical class NCO XMYQHJDBLRZMLW-UHFFFAOYSA-N 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- IOLCXVTUBQKXJR-UHFFFAOYSA-M potassium bromide Chemical compound [K+].[Br-] IOLCXVTUBQKXJR-UHFFFAOYSA-M 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 2
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 description 2
- 150000003672 ureas Chemical class 0.000 description 2
- QAGFPFWZCJWYRP-UHFFFAOYSA-N 1,1-bis(hydroxymethyl)urea Chemical compound NC(=O)N(CO)CO QAGFPFWZCJWYRP-UHFFFAOYSA-N 0.000 description 1
- TUMNHQRORINJKE-UHFFFAOYSA-N 1,1-diethylurea Chemical compound CCN(CC)C(N)=O TUMNHQRORINJKE-UHFFFAOYSA-N 0.000 description 1
- URGSMJLDEFDWNX-UHFFFAOYSA-N 1-butylnaphthalene Chemical compound C1=CC=C2C(CCCC)=CC=CC2=C1 URGSMJLDEFDWNX-UHFFFAOYSA-N 0.000 description 1
- ZJVMHPVIAUKERS-UHFFFAOYSA-N 2-hexylbutanedioic acid Chemical compound CCCCCCC(C(O)=O)CC(O)=O ZJVMHPVIAUKERS-UHFFFAOYSA-N 0.000 description 1
- CPELXLSAUQHCOX-UHFFFAOYSA-M Bromide Chemical compound [Br-] CPELXLSAUQHCOX-UHFFFAOYSA-M 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- MGJKQDOBUOMPEZ-UHFFFAOYSA-N N,N'-dimethylurea Chemical compound CNC(=O)NC MGJKQDOBUOMPEZ-UHFFFAOYSA-N 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- QMJDEXCUIQJLGO-UHFFFAOYSA-N [4-(methylamino)phenyl] hydrogen sulfate Chemical compound CNC1=CC=C(OS(O)(=O)=O)C=C1 QMJDEXCUIQJLGO-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 235000011126 aluminium potassium sulphate Nutrition 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000002508 contact lithography Methods 0.000 description 1
- 150000003950 cyclic amides Chemical class 0.000 description 1
- 238000002845 discoloration Methods 0.000 description 1
- MQRJBSHKWOFOGF-UHFFFAOYSA-L disodium;carbonate;hydrate Chemical compound O.[Na+].[Na+].[O-]C([O-])=O MQRJBSHKWOFOGF-UHFFFAOYSA-L 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- CBEQRNSPHCCXSH-UHFFFAOYSA-N iodine monobromide Chemical compound IBr CBEQRNSPHCCXSH-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- PSZYNBSKGUBXEH-UHFFFAOYSA-N naphthalene-1-sulfonic acid Chemical compound C1=CC=C2C(S(=O)(=O)O)=CC=CC2=C1 PSZYNBSKGUBXEH-UHFFFAOYSA-N 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- ODGAOXROABLFNM-UHFFFAOYSA-N polynoxylin Chemical compound O=C.NC(N)=O ODGAOXROABLFNM-UHFFFAOYSA-N 0.000 description 1
- 229940050271 potassium alum Drugs 0.000 description 1
- GRLPQNLYRHEGIJ-UHFFFAOYSA-J potassium aluminium sulfate Chemical compound [Al+3].[K+].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O GRLPQNLYRHEGIJ-UHFFFAOYSA-J 0.000 description 1
- 235000010265 sodium sulphite Nutrition 0.000 description 1
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 description 1
- 235000019345 sodium thiosulphate Nutrition 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
- G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
- G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
- G03C5/40—Chemically transforming developed images
Definitions
- This invention relates to photographic black and white negatives and prints, and particularly to antifading baths employed in the treatment of black and white photographic taking and printing materials.
- Photographic negative and positive prints having a metallic silver image particularly those negatives and prints which have a warm image tone and are characterized by a small particle size of metallic silver, show under certain conditions of storage, a propensity to fade, i. e., lose density and change the color of the silver image.
- This susceptibility is most marked when the negative or print is exposed to an atmosphere containing gaseous products of the oxides of nitrogen, oxides of sulfur, and reactive ,sulfiding compounds, such as hydrogen sulfides (H28) and the like, which are frequently encountered in ore smelting, soft coal burning and artificial gas burning areas.
- H28 hydrogen sulfides
- the addition product is simply dissolved in water and the resulting solution utilized in the treatment of the photographic material subsequent to exposure and development,
- concentration of the addition product is not critical and varies within a wide range.
- the actual concentration employed will depend upon the type of emulsion used in the photographic black and white material and varies between 0.5 and 20%. For practical purposes, concentrations ranging between 2 and are preferred.
- a surface active agent such as the formaldehyde condensation product of naphthalene sulfonic acid sold under the trade name of Tamol NNO, the sodium sulfonate of hexylsuccinate, the sodium sulfonate of butylnaphthalene and the like.
- the black and white photographic materials which may be treated subsequent to exposure and development are contact printing paper, projection printing paper, ordinary black and white film which may be a positive or negative and motion picture film.
- Example I A black and white negative was printed by projection on two 5 x '7 sheets of black and white chlorobromide projection paper. The exposed sheets were developed for 1 to 2 minutes at C. in a warm tone developer of the following composition.
- Acetic acid 45.0 cc. Water to make 1 liter. The prints were then washed for 2 minutes in running water and hardened for 5 minutes in an acid hardening fix of the following composition:
- the sodium thiosulfate is separately dissolved in a sufficient amount of water and then added to a solution of the remaining ingredients and brought up to volume. After fixing, the prints were washed for 10 minutes in running water at 20 C.
- Example II Example II was repeated with the exception that 4 grams of N,N'-dimethylolurea were replaced by 5 grams of N-methylolmethylenebismonoethylurea.
- the black and white print washed in plain water and exposed for several days to an atmosphere containing oxides of nitrogen showed considerable fading and change of color in the silver image, whereas the print washed with the aqueous solution containing the formaldehyde urea addition product showed no fading or change of color.
- Example III Example III was again repeated with the exception that 4 grams of N,N'-dimethylolurea were replaced by 10 grams of N,N'-dimethyloluron. The results obtained were identical with those of Example I.
- Example IV Example I was again repeated with the exception that 4 grams of N,N'-dimethylolurea were replaced by 5 grams of a water-soluble resinous condensation product of formaldehyde and urea, prepared in accordance with the procedure described on page 631 of Carleton Ellis book The Chemistry of Synthetic Resins, (Reinhold Publishing Corp., New York, N. Y., 1935). The results obtained were identical with those of Example I. r
- the treating baths which I have described and employed may be used in treating various kinds of silver halide emulsions, such as chloride, bromide, chlorobromide, bromoiodide, or chlorobromoiodide emulsions subsequent to exposure and development.
- silver halide emulsions such as chloride, bromide, chlorobromide, bromoiodide, or chlorobromoiodide emulsions subsequent to exposure and development.
- the improvement which comprises preventing the fading and change of color of the silver images upon exposure to the atmosphere by treating the emulsion layer subsequent to development with an aqueous solution containing a water-soluble addition product of formaldehyde and a urea selected from the class consisting of those having the following formula:
- R, R1 and R2 each represent a member selected from the class consisting of hydrogen and lower alkyl, and wherein R2 is always hydrogen when both R and R1 are lower alkyl.
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Silver Salt Photography Or Processing Solution Therefor (AREA)
Description
Patented Feb. 24, 1953 ANTIFADING BATHS FOR PHOTOGRAPHIC BLACK AND WHITE MATERIALS E. Scudder Mackey, Binghamton, N. Y.
No Drawing. Application October 23, 1951,
Serial No. 252,808
G'Claims. 1
This invention relates to photographic black and white negatives and prints, and particularly to antifading baths employed in the treatment of black and white photographic taking and printing materials.
It is known that open chain and cyclic amides containing at least onemethylol radical attached directly to the amide nitrogen atom have been suggested for the production of silver images having a blue-black image tone. These compounds may be added to silver halide emulsions, subbing layers or backing layers or may be used in the developer solution to achieve the desired blue-black toning effect.
Photographic negative and positive prints having a metallic silver image, particularly those negatives and prints which have a warm image tone and are characterized by a small particle size of metallic silver, show under certain conditions of storage, a propensity to fade, i. e., lose density and change the color of the silver image. This susceptibility is most marked when the negative or print is exposed to an atmosphere containing gaseous products of the oxides of nitrogen, oxides of sulfur, and reactive ,sulfiding compounds, such as hydrogen sulfides (H28) and the like, which are frequently encountered in ore smelting, soft coal burning and artificial gas burning areas. 7
The utilization of the open chain and cyclic methylol amides as suggested by the prior art is ineffective in alleviating the fading problem since the various processing steps to which the photo-v graphic material is subjected, wash out the methylol amides. As a consequence, there are none left after the final washing treatment. Moreover, the presence of the methylol amides during the development step favors the formation of blue-black tones and precludes the ob tainment of pictures having .a warm image tone.
It is an object of the present invention to eliminate the fading and change of the color of the silver image in blackand white negatives and prints upon exposure tor'the atmosphere.
Other objects and advantages will=appear hereinafter. l r
I have discovered that the above objects are accomplished by treating a photographic black and white material subsequent to exposure and development with a bath of an aqueous solution containing a. water-soluble addition product of formaldehyde and urea. The ureas which readily The following are examples of suitable ureas which may be reacted with formaldehyde:
Urea N,N-dimethylurea N-methylurea N,N-dimethylurea N -ethylurea N,N-,diethylurea N-propylurea N,N-diethylurea N-butylurea The following compounds are illustrative of the reaction products of formaldehyde and a urea compound which may be employed as fading inhibitors:
( Ber. 41, 26
NHomoH Ber. 41, 26
(3) Annalen 361, 134
NHC 2H N N-methylol nethylenebismonoethylurea Annelen 361, 135
N C Ha) a N H 1. 2 13 .NGmethylol-RN-fiimethylurea Annalen 361, 157
fi a 0310K nom 'N-methylol-'N,N'-dimethylurea CHr-N cHrNHzoH N,N-dimethyloluron By utilizing a bath containing the addition products, the tendency of the developed silver images in black and white negatives, positives and prints to fade and change intone or color upon storage or exposure to an atmosphere containing the aforementioned gases is completely eliminated for an indefinite period of time. The exact operation of the addition products upon the developed silver images is still unknown. It is believed for the sake of temporary explanation that the particles of the addition products protect the silver images from the attack of the aforementioned gases without adversely affecting the silver images.
In preparing the antifading baths of the present invention, the addition product is simply dissolved in water and the resulting solution utilized in the treatment of the photographic material subsequent to exposure and development, The concentration of the addition product is not critical and varies within a wide range. The actual concentration employed will depend upon the type of emulsion used in the photographic black and white material and varies between 0.5 and 20%. For practical purposes, concentrations ranging between 2 and are preferred.
To facilitate the penetration of the addition product into the silver halide emulsion layer subsequent to exposure and development, it may be desirable to incorporate a surface active agent. such as the formaldehyde condensation product of naphthalene sulfonic acid sold under the trade name of Tamol NNO, the sodium sulfonate of hexylsuccinate, the sodium sulfonate of butylnaphthalene and the like.
The black and white photographic materials which may be treated subsequent to exposure and development are contact printing paper, projection printing paper, ordinary black and white film which may be a positive or negative and motion picture film.
The following examples will serve to illustrate the methods for accomplishing the above objects but are not to be construed as limiting the invention.
Example I A black and white negative was printed by projection on two 5 x '7 sheets of black and white chlorobromide projection paper. The exposed sheets were developed for 1 to 2 minutes at C. in a warm tone developer of the following composition.
Gms. p-Monomethylaminophenol sulfate 0.8 Sodium sulfite 12.0
Hydroquinone 3.3 Sodium carbonate (monohydrate) 12.0 Potassium bromide 1.4
Water to make 1 liter.
The developed papers were shortstopped for 2 minutes in at shortstop bath of the following composition:
Acetic acid, 45.0 cc. Water to make 1 liter. The prints were then washed for 2 minutes in running water and hardened for 5 minutes in an acid hardening fix of the following composition:
Potassium alum gmq Water to make 1 liter.
In preparing the above fixing solution, the sodium thiosulfate is separately dissolved in a sufficient amount of water and then added to a solution of the remaining ingredients and brought up to volume. After fixing, the prints were washed for 10 minutes in running water at 20 C.
After the final washing, one print was set aside while the other was rinsed for 3 minutes in an aqueous solution containing 4.3% of N,N'-dimethylolurea and then dried. At this point, both prints appeared identical and were characterized by a warm image tone. The prints were then stored in an atmosphere containing the combustion product of an unvented burner utilizing natural gas. The print rinsed in the solution containing the N,N-dimethylolurea showed no fading or change of color in the silver image, whereas the untreated print showed considerable fading and discoloration.
Example II Example I was repeated with the exception that 4 grams of N,N'-dimethylolurea were replaced by 5 grams of N-methylolmethylenebismonoethylurea. The black and white print washed in plain water and exposed for several days to an atmosphere containing oxides of nitrogen showed considerable fading and change of color in the silver image, whereas the print washed with the aqueous solution containing the formaldehyde urea addition product showed no fading or change of color.
Example III Example I was again repeated with the exception that 4 grams of N,N'-dimethylolurea were replaced by 10 grams of N,N'-dimethyloluron. The results obtained were identical with those of Example I.
- Example IV Example I was again repeated with the exception that 4 grams of N,N'-dimethylolurea were replaced by 5 grams of a water-soluble resinous condensation product of formaldehyde and urea, prepared in accordance with the procedure described on page 631 of Carleton Ellis book The Chemistry of Synthetic Resins, (Reinhold Publishing Corp., New York, N. Y., 1935). The results obtained were identical with those of Example I. r
The treating baths which I have described and employed may be used in treating various kinds of silver halide emulsions, such as chloride, bromide, chlorobromide, bromoiodide, or chlorobromoiodide emulsions subsequent to exposure and development.
Various modifications of this invention will occur to persons skilled in the art and it is, therefore, understood that the patent granted shall only be limited by the appended claims.
I claim:
1. In the process of producing silver images in a silver halide emulsion layer by exposing the emulsion, developing, fixed and washing the same, the improvement which comprises preventing the fading and change of color of the silver images upon exposure to the atmosphere by treating the emulsion layer subsequent to development with an aqueous solution containing a water-soluble addition product of formaldehyde and a urea selected from the class consisting of those having the following formula:
wherein R, R1 and R2 each represent a member selected from the class consisting of hydrogen and lower alkyl, and wherein R2 is always hydrogen when both R and R1 are lower alkyl.
No references cited.
Claims (1)
1. IN THE PROCESS OF PRODUCING SILVER IMAGES IN A SILVER HALIDE EMULSION LAYER BY EXPOSING THE EMULSION, DEVELOPING, FIXED AND WASHING THE SAME, THE IMPROVEMENT WHICH COMPRISES PREVENTING THE FADING AND CHANGE OF COLOR OF THE SILVER IMAGES UPON EXPOSURE TO THE ATMOSPHERE BY TREATING THE EMULSION LAYER SUBSEQUENT TO DEVELOPMENT WITH AN AQUEOUS SOLUTION CONTAINING A WATER-SOLUBLE ADDITION PRODUCT OF FORMALDEHYDE AND A UREA SELECTED FROM THE CLASS CONSISTING OF THOSE HAVING THE FOLLOWING FORMULA:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US252808A US2629661A (en) | 1951-10-23 | 1951-10-23 | Antifading baths for photographic black and white materials |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US252808A US2629661A (en) | 1951-10-23 | 1951-10-23 | Antifading baths for photographic black and white materials |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2629661A true US2629661A (en) | 1953-02-24 |
Family
ID=22957639
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US252808A Expired - Lifetime US2629661A (en) | 1951-10-23 | 1951-10-23 | Antifading baths for photographic black and white materials |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US2629661A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1027984B (en) * | 1954-02-26 | 1958-04-10 | Polaroid Corp | Process for washing and protecting a silver photographic image |
-
1951
- 1951-10-23 US US252808A patent/US2629661A/en not_active Expired - Lifetime
Non-Patent Citations (1)
| Title |
|---|
| None * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1027984B (en) * | 1954-02-26 | 1958-04-10 | Polaroid Corp | Process for washing and protecting a silver photographic image |
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