US2857317A - Treatment of skins and hides - Google Patents
Treatment of skins and hides Download PDFInfo
- Publication number
- US2857317A US2857317A US617216A US61721656A US2857317A US 2857317 A US2857317 A US 2857317A US 617216 A US617216 A US 617216A US 61721656 A US61721656 A US 61721656A US 2857317 A US2857317 A US 2857317A
- Authority
- US
- United States
- Prior art keywords
- skins
- hide
- acid
- water
- hides
- 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
- 239000002253 acid Substances 0.000 claims description 17
- 102000035195 Peptidases Human genes 0.000 claims description 15
- 108091005804 Peptidases Proteins 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 9
- 230000002255 enzymatic effect Effects 0.000 claims description 6
- 238000007654 immersion Methods 0.000 claims description 4
- 239000000843 powder Substances 0.000 claims description 4
- XLYOFNOQVPJJNP-PWCQTSIFSA-N Tritiated water Chemical compound [3H]O[3H] XLYOFNOQVPJJNP-PWCQTSIFSA-N 0.000 claims 1
- 210000003491 skin Anatomy 0.000 description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 12
- 229940024999 proteolytic enzymes for treatment of wounds and ulcers Drugs 0.000 description 9
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 7
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 7
- 235000011130 ammonium sulphate Nutrition 0.000 description 7
- 235000002639 sodium chloride Nutrition 0.000 description 7
- 230000009471 action Effects 0.000 description 6
- 102000004190 Enzymes Human genes 0.000 description 5
- 108090000790 Enzymes Proteins 0.000 description 5
- 102000001400 Tryptase Human genes 0.000 description 5
- 108060005989 Tryptase Proteins 0.000 description 5
- 229940088598 enzyme Drugs 0.000 description 5
- 150000003839 salts Chemical class 0.000 description 5
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 4
- 230000008961 swelling Effects 0.000 description 4
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 3
- 102000008186 Collagen Human genes 0.000 description 3
- 108010035532 Collagen Proteins 0.000 description 3
- 235000011941 Tilia x europaea Nutrition 0.000 description 3
- 108010089934 carbohydrase Proteins 0.000 description 3
- 229920001436 collagen Polymers 0.000 description 3
- 239000010985 leather Substances 0.000 description 3
- 239000004571 lime Substances 0.000 description 3
- 230000007935 neutral effect Effects 0.000 description 3
- 102000004882 Lipase Human genes 0.000 description 2
- 108090001060 Lipase Proteins 0.000 description 2
- 239000004367 Lipase Substances 0.000 description 2
- 239000004365 Protease Substances 0.000 description 2
- DWAQJAXMDSEUJJ-UHFFFAOYSA-M Sodium bisulfite Chemical compound [Na+].OS([O-])=O DWAQJAXMDSEUJJ-UHFFFAOYSA-M 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 235000019270 ammonium chloride Nutrition 0.000 description 2
- 230000001580 bacterial effect Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 210000002615 epidermis Anatomy 0.000 description 2
- 235000019421 lipase Nutrition 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 244000005700 microbiome Species 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000011780 sodium chloride Substances 0.000 description 2
- 235000010267 sodium hydrogen sulphite Nutrition 0.000 description 2
- 229910052979 sodium sulfide Inorganic materials 0.000 description 2
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 description 2
- 241000228197 Aspergillus flavus Species 0.000 description 1
- 244000063299 Bacillus subtilis Species 0.000 description 1
- 235000014469 Bacillus subtilis Nutrition 0.000 description 1
- 241000894006 Bacteria Species 0.000 description 1
- 101000795074 Homo sapiens Tryptase alpha/beta-1 Proteins 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 102100029639 Tryptase alpha/beta-1 Human genes 0.000 description 1
- 150000001844 chromium Chemical class 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000035617 depilation Effects 0.000 description 1
- 230000002951 depilatory effect Effects 0.000 description 1
- 238000010410 dusting Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 235000021317 phosphate Nutrition 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 235000021110 pickles Nutrition 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 102000004169 proteins and genes Human genes 0.000 description 1
- 108090000623 proteins and genes Proteins 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C14—SKINS; HIDES; PELTS; LEATHER
- C14C—CHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
- C14C1/00—Chemical treatment prior to tanning
Definitions
- This invention relates to tin-improvement in depilating skins and hides and in preparing them for tanning.
- the acid bating follows treatment of the enzymatically depilated skins and hides in swelling lime and, of course, precedes the tanning operation.
- the combination of depilating by applying enzyme products in powdered form to green or soaked skins followed by acid bating results, after tanning, in leathers having a most desirable firm grain.
- the proteolytic enzymes that are preferred in the acid hating step are those formed from microorganisms, namely, the proteolytic enzymes from molds and bacteria.
- carbohydrases formed from microorganisms and water-soluble mold lipases may also advantageously be employed.
- the addition of anhydrous phosphates has also proven favorable.
- a skin from the soaking pit i. e., one that has not been subjected to any alkaline treatment or swelling, is extremely resistant to depilatory enzymes. Consequently, such a skin is not in danger of forming leather having an undesirable grain.
- the unhaired skin is introduced in very clean form into the swelling lime and is thereupon fleshed, scudded and delimed.
- the enzymatic hating which then is effected in an acid bath in accordance with the invention acts very gently on the completely fallen and unhaired skin.
- the production of a loose grain caused by the action of proteolytic enzymes on an unhaired hide under alkaline conditions is, therefore, avoided and instead, a highly desirable, firm grain is produced.
- the necessary additional quantity of acid and neutral salt can be added to the hating liquor after the action of the enzymes has been completed. Tanning can then follow.
- Example 1 Dried goatskins were enzymatically softened, then washed and fulled for one-half hour with 3% mold tryptase from Aspergillus flavus without addition of water.
- the treated skins were unhaired after six hours, smoothed, washed and after-limed for two days with 400% of a sodium sulfide solution of 1 B. After this time, the treated skins were rinsed, de-swollen with ammonium chloride solution and then bated for twentyfour hours with 300% water at 20-24 C. 8% common salt 1.5% mold tryptase 1% ammonium sulfate
- the pH of the bating liquor was maintained between 4 and 5.
- Example 2 After rinsing, the treated skins were de-swollen with ammonium sulfate and finally bated for eight hours with 300% water at 2022 C., pH 4 to 5 8% salt 1% mold tryptase 0.25% carbohydrase derived from mold 0.5% ammonium sulfate When the bating was ended, the skins were pickled in the liquor after 8% common salt and acid were added to reduce the pH to 2.5, whereupon tanning was accomplished with chromium salts.
- Example 3 Salted calfskins were soaked in water, then after-treated for twelve hours with 500% water 0.2% bacterial protease 0.4% sodium bisulfite calc. 0.5% ammonium sulfate 3) The treated skins were then tumbled in the drum without addition of water for thirty minutes with 3 mold tryptase 0.5% sodium bisulfite calc. 0.5% ammonium sulfate After eight hours, the treated skins were covered with Example 4 Dried goatskins Wei-e enzymatically soaked, then tumbled without addition of water for one hour with 3% bacterial protease from Bacillus subtilis.
- the treated skins were unhaired, then after-timed for twenty-four hours with 400% sodium sulfide solution of 1.5 B., then rinsed, de-swollen with ammonium chloride and bated for one hour ata pH' of 8 to 8.5 with 300% water at 32 C. 0.2% pancreatic tryptase 0.8% ammonium sulfate
- the skins were then bated for twenty-four hours in'an acid medium having a pH of 3 to with 300% water at 1820 C. 8% salt 0.6% mold tryptase 0.6% ammonium sulfate.
- a method for preparing a hide for tanning which comprises applying proteolytic enzyme, in powder form, to a hide, permitting enzymatic action to take place at ambient temperature without immersion in water, unhairing the treated hide, and hating the unhaired hide enzymatically in an acid bating liquor having a pH of from 3 to 5.
- a method for preparing-abide for tanning which comprises depilating the hide by applying to it a proteolytic enzyme in powder form and permitting enzymaticfaction to take place at ambient temperature without immersion in water, hating the depilated hide enzymatically in an acid bating liquor having a pH of from 3 to 5 and, after completion of the enzymatic action, pickling the hide by addition of acid and neutral salt to the bating liquor.
- a method for preparing a hide for tanning which includes depilating the hide by applying thereto a proteolytic enzyme in powder form and permitting en'- zymatic action to take place at ambient temperature without immersion in water, the improvement which comprises hating the depilated hide enzymatically in an acid bath having a pH of from 3 to 5.
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Treatment And Processing Of Natural Fur Or Leather (AREA)
Description
United States Patent TREATMENT OF SKINS AND HIDES Otto Grimm, Darmstadt, Germany, assignor to Rohm & Haas G. m. b. H., Darmstadt, Germany No Drawing. Application October 22, 1956 Serial No. 617,216
This invention relates to tin-improvement in depilating skins and hides and in preparing them for tanning.
It is customary, in the production of leather, to treat skins and hides in an alkaline swelling lime after they have been soaked. In this way the hair and epidermis located above the derma are solubilized while hair roots and traces of epidermis remain in the follicles. This send is removed in the alkaline hating following the alkaline liming. At the same time the collagen is loosened so that the tans can enter fully into action in the subsequent tanning process.
In order to obtain a complete removal of the scud by the action of proteolytic enzymes, the bating must be effected in an alkaline medium. Unfortunately, however, this frequently results in damage to the collagen by the proteolytic enzymes, and ultimately in an insufficiently firm grain forthe leather.
I have already disclosed, in my earlier application Serial No. 533,227, filed September 8, 1955, of which this application is a continuation-in-part, that the enzymatic unhairing and dewooling of skins and hides can be carried out with the aid of proteolytic enzymes by applying the enzyme products in powdered form to green or soaked skins, preferably by sprinkling or dusting on the flesh side, and further that this mode of action has the advantage, over depilation in an aqueous bath, of resulting in a practically complete removal of the scud.
I have now found that the advantageous results obtained by reason of the treatment described in my earlier application can be further enhanced by hating the skins and hides, thus depilated, in an acid bath having a pH of 3 to 5, preferably in the presence of neutral salt. The attack of the bating proteolytic enzymes on the collagen is sufiicient when operating in an acid bath to eifect the necessary loosening thereof, without however bringing about too strong a decomposition of the protein substance.
Most advantageously, the acid bating follows treatment of the enzymatically depilated skins and hides in swelling lime and, of course, precedes the tanning operation. The combination of depilating by applying enzyme products in powdered form to green or soaked skins followed by acid bating results, after tanning, in leathers having a most desirable firm grain.
The proteolytic enzymes that are preferred in the acid hating step are those formed from microorganisms, namely, the proteolytic enzymes from molds and bacteria. In addition to the proteolytic enzymes, carbohydrases formed from microorganisms and water-soluble mold lipases may also advantageously be employed. The addition of anhydrous phosphates has also proven favorable.
A skin from the soaking pit, i. e., one that has not been subjected to any alkaline treatment or swelling, is extremely resistant to depilatory enzymes. Consequently, such a skin is not in danger of forming leather having an undesirable grain. The unhaired skin is introduced in very clean form into the swelling lime and is thereupon fleshed, scudded and delimed. The enzymatic hating which then is effected in an acid bath in accordance with the invention acts very gently on the completely fallen and unhaired skin. The production of a loose grain caused by the action of proteolytic enzymes on an unhaired hide under alkaline conditions is, therefore, avoided and instead, a highly desirable, firm grain is produced.
In some instances it may be advisable to combine a weak enzymatic hating in alkaline medium with the deliming. Such a treatment, however, is not suflicient for obtaining the hating effect so that the subsequent bating in an acid medium is in any event necessary.
If it is desired to pickle the unhaired hides at high acidity following treatment in the acid bating liquor and prior to the tanning operation, the necessary additional quantity of acid and neutral salt can be added to the hating liquor after the action of the enzymes has been completed. Tanning can then follow.
The advantages and utility of the invention will become further apparent from the following examples included to illustrate the best modes now contemplated for carrying out the invention. The percentages are based on the dry weight of the skins or hides treated.
Example 1 Dried goatskins were enzymatically softened, then washed and fulled for one-half hour with 3% mold tryptase from Aspergillus flavus without addition of water. The treated skins were unhaired after six hours, smoothed, washed and after-limed for two days with 400% of a sodium sulfide solution of 1 B. After this time, the treated skins were rinsed, de-swollen with ammonium chloride solution and then bated for twentyfour hours with 300% water at 20-24 C. 8% common salt 1.5% mold tryptase 1% ammonium sulfate The pH of the bating liquor was maintained between 4 and 5.
Example 2 After rinsing, the treated skins were de-swollen with ammonium sulfate and finally bated for eight hours with 300% water at 2022 C., pH 4 to 5 8% salt 1% mold tryptase 0.25% carbohydrase derived from mold 0.5% ammonium sulfate When the bating was ended, the skins were pickled in the liquor after 8% common salt and acid were added to reduce the pH to 2.5, whereupon tanning was accomplished with chromium salts.
Example 3 Salted calfskins were soaked in water, then after-treated for twelve hours with 500% water 0.2% bacterial protease 0.4% sodium bisulfite calc. 0.5% ammonium sulfate 3) The treated skins were then tumbled in the drum without addition of water for thirty minutes with 3 mold tryptase 0.5% sodium bisulfite calc. 0.5% ammonium sulfate After eight hours, the treated skins were covered with Example 4 Dried goatskins Wei-e enzymatically soaked, then tumbled without addition of water for one hour with 3% bacterial protease from Bacillus subtilis. After eighteen hours, the treated skins were unhaired, then after-timed for twenty-four hours with 400% sodium sulfide solution of 1.5 B., then rinsed, de-swollen with ammonium chloride and bated for one hour ata pH' of 8 to 8.5 with 300% water at 32 C. 0.2% pancreatic tryptase 0.8% ammonium sulfate The skins were then bated for twenty-four hours in'an acid medium having a pH of 3 to with 300% water at 1820 C. 8% salt 0.6% mold tryptase 0.6% ammonium sulfate.
It is to be understood that various modifications will readily become apparent to those skilled in the art upon reading this description. All such modifications are in- '4 tended to be included within the scope of the invention as defined in the appended claims.
I claim:
1. A method for preparing a hide for tanning which comprises applying proteolytic enzyme, in powder form, to a hide, permitting enzymatic action to take place at ambient temperature without immersion in water, unhairing the treated hide, and hating the unhaired hide enzymatically in an acid bating liquor having a pH of from 3 to 5. v
2. The method defined in claim 1 wherein the enzymes in the hating liquor are proteolytic enzymes.
3. The method defined in claim 2 wherein the hating liquor additionally contains carbohydrases. I
4. The method defined in claim 2 wherein the hating liquor additionally contains water-soluble mold lipases.
5. The method defined in claim 2 wherein the depilated hide is bated in a weakly alkaline hating liquor before the acid b ating.
6. A method for preparing-abide for tanning which comprises depilating the hide by applying to it a proteolytic enzyme in powder form and permitting enzymaticfaction to take place at ambient temperature without immersion in water, hating the depilated hide enzymatically in an acid bating liquor having a pH of from 3 to 5 and, after completion of the enzymatic action, pickling the hide by addition of acid and neutral salt to the bating liquor.
7. In a method for preparing a hide for tanning which includes depilating the hide by applying thereto a proteolytic enzyme in powder form and permitting en'- zymatic action to take place at ambient temperature without immersion in water, the improvement which comprises hating the depilated hide enzymatically in an acid bath having a pH of from 3 to 5.
References Cited in the file" of this'pat'ent UNITED STATES PATENTS
Claims (1)
1. A METHOD FOR PREPARING A HIDE FOR TANNING WHICH COMPRISES APPLYING PROTEOLYTIC ENZYME, IN POWDER FORM, TO A HIDE, PERMITTING ENZYMATIC ACTION TO TAKE PLACE AT AMBIENT TEMPERATURE WITHOUT IMMERSION IN WATER, UNHAIRING THE TREATED HIDE, AND BATING THE UNHAIRED HIDE ENZYMATICALLY IN AN ACID BATING LIQUOR HAVING A PH OF FROM 3 TO 5.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2857317X | 1955-03-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2857317A true US2857317A (en) | 1958-10-21 |
Family
ID=7999813
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US617216A Expired - Lifetime US2857317A (en) | 1955-03-30 | 1956-10-22 | Treatment of skins and hides |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US2857317A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2988488A (en) * | 1958-04-11 | 1961-06-13 | Mearl Corp | Enzymatic dehairing of hides and skins |
| US3173847A (en) * | 1962-12-26 | 1965-03-16 | Pfizer & Co C | Process of producing keratinase |
| US3203868A (en) * | 1962-04-06 | 1965-08-31 | Roehm & Haas Gmbh | Method for preparing tannable depilated hides |
| US3256157A (en) * | 1959-02-20 | 1966-06-14 | Astra Pharma Prod | Agents having a fibrinolytic activity and being derived from molds and a process of making and using same |
| FR2019799A1 (en) * | 1968-10-03 | 1970-07-10 | Roehm & Haas Gmbh | |
| US3898129A (en) * | 1971-10-28 | 1975-08-05 | Kyowa Hakko Kogyo Kk | Enzymatically hydrolyzed composition of skin rag and derivatives thereof |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1936074A (en) * | 1930-07-30 | 1933-11-21 | Frosted Foods Co Inc | Preparation of food products |
| US2157969A (en) * | 1936-02-08 | 1939-05-09 | Rohm Otto | Method for producing hides with the aid of mold tryptases |
| US2169148A (en) * | 1938-06-01 | 1939-08-08 | American Cyanamid & Chem Corp | Unhairing of hides and skins |
| US2215055A (en) * | 1938-10-08 | 1940-09-17 | Rohm Otto | Method for preparing hides using mold tryptases, and a neutral to weakly acid reaction |
-
1956
- 1956-10-22 US US617216A patent/US2857317A/en not_active Expired - Lifetime
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1936074A (en) * | 1930-07-30 | 1933-11-21 | Frosted Foods Co Inc | Preparation of food products |
| US2157969A (en) * | 1936-02-08 | 1939-05-09 | Rohm Otto | Method for producing hides with the aid of mold tryptases |
| US2169148A (en) * | 1938-06-01 | 1939-08-08 | American Cyanamid & Chem Corp | Unhairing of hides and skins |
| US2215055A (en) * | 1938-10-08 | 1940-09-17 | Rohm Otto | Method for preparing hides using mold tryptases, and a neutral to weakly acid reaction |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2988488A (en) * | 1958-04-11 | 1961-06-13 | Mearl Corp | Enzymatic dehairing of hides and skins |
| US3256157A (en) * | 1959-02-20 | 1966-06-14 | Astra Pharma Prod | Agents having a fibrinolytic activity and being derived from molds and a process of making and using same |
| US3203868A (en) * | 1962-04-06 | 1965-08-31 | Roehm & Haas Gmbh | Method for preparing tannable depilated hides |
| DE1230169B (en) * | 1962-04-06 | 1966-12-08 | Roehm & Haas Gmbh | Process for the production of tanned bare |
| US3173847A (en) * | 1962-12-26 | 1965-03-16 | Pfizer & Co C | Process of producing keratinase |
| FR2019799A1 (en) * | 1968-10-03 | 1970-07-10 | Roehm & Haas Gmbh | |
| US3898129A (en) * | 1971-10-28 | 1975-08-05 | Kyowa Hakko Kogyo Kk | Enzymatically hydrolyzed composition of skin rag and derivatives thereof |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3986926A (en) | Method for preparing tannable pelts from animal skins and hides | |
| US3966551A (en) | Method for preparing tannable pelts from animal skins and hides | |
| US4636222A (en) | Enzymatic unhairing method | |
| ATE112322T1 (en) | HAIR PRESERVING LIMINATION PROCESS. | |
| US2857317A (en) | Treatment of skins and hides | |
| ES8403512A1 (en) | Process for producing unhaired, storable hides and skins | |
| US3203868A (en) | Method for preparing tannable depilated hides | |
| US2988488A (en) | Enzymatic dehairing of hides and skins | |
| US2857316A (en) | Enzymatic unhairing and dewooling process | |
| US3623950A (en) | Enzymatic dehairing process | |
| US2157969A (en) | Method for producing hides with the aid of mold tryptases | |
| US3558430A (en) | Process for the loosening of dead hairs in fur pelts | |
| US2033163A (en) | Process of depilating and rating hides and a bate for these purposes | |
| US2225601A (en) | Dehairing of skins and hides | |
| US2212750A (en) | Method of treating hides, skins, and pelts | |
| CH350067A (en) | Process for the production of ready-to-tan pelts | |
| US3133002A (en) | Treatment of hides | |
| US2871162A (en) | Process for the treatment of hides and skins with mucolytic enzymes | |
| US2132579A (en) | Method for producing unhaired hides with the aid of mold tryptases | |
| US2215055A (en) | Method for preparing hides using mold tryptases, and a neutral to weakly acid reaction | |
| US3549495A (en) | Process for loosening the fiber structure of tanned furs | |
| US2016260A (en) | Process of unhairing hides and skins | |
| US2150961A (en) | Tanning | |
| US3493318A (en) | Tanning composition made from a basic chrome sulfate and a tris(hydroxyacetato)chromiate | |
| SU1306481A3 (en) | Method for producing leather and wool |