Abstract: What is disclosed is a process for the unhairing and subsequent curing of hides and skins, which comprises washing flayed skins and hides to remove adhering dirt, then soaking said skins and hides and freeing them of hair and scud with a short term unhairing, reversing the swelling of said skins and hides and neutralizing them, and curing said skins and hides with salt, said skins and hides being mechanically fleshed either after washing or at some later time in the process as recited.

Abstract: What are disclosed are improved methods for the preparation of leather wherein, in one or more steps for preparing leather from limed animal skins or hides, including beamhouse operations such as deliming, bating, pickling, and degreasing to prepare unhaired tannable hides from animal skins or hides, and including subsequent tanning, retanning, and dyeing steps performed on said unhaired tannable hides, small amounts of a high polymeric water soluble cellulose ether or of an acrylic polymer are added to at least one of the treating baths involved in such method steps as a lubricant for said skins or hides.

Abstract: A method and a device for converting and separating substances dissolved in a carrier fluid, more particularly proteides or proteins, by adding and mixing with an agent, e.g. enzymes, which brings about the chemical reaction or the build-up or breakdown of the molecules of the substances and causes them to precipitate. In addition these substances are mixed and come to an accelerated reaction with the agent in at least one circuit flow through a jet immersion reactor while a gas is supplied intensively thereto before froth flotation of the precipitated substances is carried out after adding means assisting flotation.

Abstract: What is disclosed are improved methods for the preparation of leather wherein, in one or more steps for preparing leather from animal skins or hides, including beamhouse operations such as soaking, dehairing, opening of the hide structure, deliming, bating, pickling, and degreasing to prepare dehaired tannable hides from animal skins or hides, and including subsequent tanning, retanning, and dying steps performed on said tannable hides, a thickening agent is added to at least one of the treating baths involved in such method steps.

Abstract: What is disclosed is a method for liming animal skins and hides which comprises treating said skins and hides with an aqueous alkaline liming liquor comprising a protective colloid, for example a protein such as gelatin, glue, or casein, or a water-soluble alkali-stable polymethacrylate.

Abstract: What is disclosed is a method for soaking preserved skins or hides adaptable to the preparation of leather which comprises soaking said skins or hides in an aqueous bath containing a compound selected from the group of compounds of the formula ##STR1## and acid addition salts thereof, wherein R taken alone is --H, --NH.sub.2, --CH.sub.3, or --NHCN, X taken alone is .dbd.O, .dbd.S, or .dbd.NH, and R and X taken together form a five- or six-membered heterocyclic ring having conjugated double bonds and containing only nitrogen as a hetero atom.

Abstract: What is disclosed are a method for treating pelts or leather in the beamhouse, for tanning, or as an aftertreatment, which method comprises contacting said pelts or leather with an aqueous solution or dispersion of a copolymer comprising monomers of a nitrogenous ester of acrylic acid or of methacrylic acid, a further different ester of acrylic acid or of methacrylic acid, and acrylic acid or methacrylic acid, whereby portions of said copolymer are deposited in the grain layer without formation of a superficial film, and pelts and leather treated by this method.

Abstract: What is disclosed is a method for soaking dried or salted fur pelts which comprises soaking said pelts in an aqueous bath containing at least one compound selected from the group consisting of compounds of the formula ##STR1## and acid addition salts of such compounds, wherein R taken alone is --H, --NH.sub.2, --CH.sub.3, or --NHCN, X taken alone is .dbd.O, .dbd.S, or .dbd.NH, and R and X taken together form a five- or six-membered heterocyclic ring having conjugated double bonds therein and containing only nitrogen as a hetero atom.

Abstract: What is disclosed is a method for liming animal skins and hides which comprises treating said skins and hides with an aqueous alkaline liming liquor comprising a protective colloid, for example a protein such as gelatin, glue, or casein, or a water-soluble alkali-stable polymethacrylate.

Abstract: What is disclosed is a method for the recovery of hair from an animal hide and for a concurrent opening of the hide structure using a proteolytic enzyme, which method comprises first pre-treating the hide, free of preservative salt, in the acid pH region with a material cleaving disulfide bridges and then, without a previous softening, concurrently loosening hair and opening the hide structure by treating said hide with a protease, effective in the alkaline region, at a pH value of about 11 to about 13.

Abstract: What is disclosed is a method for dissolving collagen-containing tissues, such as the wastes arising in leather processing, which comprises enzymatically hydrolyzing said tissues with at least one acid protease at a pH within the acid region.

Abstract: What is disclosed is a method for soaking skins or hides which comprises soaking said skins or hides in an acid bath containing at least one compound selected from the group of compounds having one of the formulasR--SH and ##STR1## wherein R is alkyl having 2 to 3 carbon atoms, alkyl having 2 or 3 carbon atoms mono-substituted with a thiol or OH group, or R is --(CH.sub.2).sub.n --(CHR.sub.1)--COOH wherein R.sub.1 is hydrogen or alkyl having 1 to 6 carbon atoms or is an amino group and n is an integer from 0 to 6, or R is R.sub.2 CO wherein R.sub.2 is alkyl having 1 to 6 carbon atoms or phenyl, and wherein R' is hydrogen, alkyl having 1 to 6 carbon atoms, or amino.

Abstract: What is disclosed is a method for the enzymatic bating of pelts with simultaneous removal of scud, which method comprises bating said pelts in the acid pH range in the presence of an amylase and a protease.

Abstract: A method is disclosed for making a water-soluble hydrolyzate of a keratinaceous starting material which comprises first subjecting said starting material to acid treatment at a pH of 2 or below and at an elevated temperature above 80.degree. C. to effect mild hydrolysis thereof and then enzymatically degrading said acid-treated material in an aqueous bath in the presence of urea with an alkaline proteinase having an activity optimum in a range between pH 9 and pH 13, the initial pH of the enzymatic treatment being within the pH range optimum for the enzyme employed.

Abstract: A method for converting blood, animal parts, bone waste, or meat scraps into useful products, which method comprises hydrolyzing such a substrate with a proteinase, preferably in the presence of urea, in an aqueous hydrolysis medium at a pH in a region in which the proteinase displays sufficient activity, subsequently inactivating the enzyme, and working up the hydrolyzate.

Abstract: A method for conditioning a collagen-containing raw material to render it adaptable to hot-water extraction of collagen and collagen degradation products therefrom, which comprises incubating said raw material in an aqueous bath containing a neutral or alkaline protease at a pH between 6.5 and 13 in the presence of a member selected from the group consisting of urea, guanidine, or an acid addition salt of quanidine.

Abstract: A method for dissolving collagen-containing skin tissue by hydrolyzing said tissue in a first stage in the presence of urea with an alkaline proteinase having an activity optimum between pH 9 and 13, said hydrolysis proceeding in a hydrolysis medium which is initially in the pH region optimum for the enzyme employed, and optionally further hydrolyzing said tissue in at least one further stage by adding a weakly alkaline, neutral, or acid proteinase to said hydrolysis medium.

Abstract: A water-soluble hydrolyzate of elastin, suitable for cosmetological use, is disclosed as is a method for making a water-soluble elastin hydrolyzate from starting materials containing elastin which comprises first subjecting said starting material to acid treatment at a pH below about 4 and at an elevated temperature and then enzymatically degrading the acid-treated material, while in comminuted form, in an aqueous bath in the presence of urea, with an alkaline proteinase having an activity optimum in a range between pH 9 and pH 13, the initial pH of the enzymatic treatment being within the pH range optimum for the enzyme employed.

Abstract: A method of treating sulfide-limed pelts in improved acid treating baths for purposes of de-liming, bating, pickling, or pre-tanning is disclosed. The improved baths contain water-soluble salts of manganese, cobalt, nickel, titanium, or zirconium, which salts discourage hydrogen sulfide formation during the acid treatment.

Abstract: A method for preparing tannable pelts from animal skins or hides, said method effecting concurrent softening, dehairing, opening of the hide structure, and bating in a single procedural step, which method comprises treating said skins or hides, free of preserving salt, with an aqueous bath having a pH between about 9 and about 12 and having dissolved therein:A. an effective amount of at least one member selected from the group consisting of a fungus protease whose optimum efficacy towards casein is at a pH above 7.0, and which protease may be replaced in whole or in part by trypsin and/or papain and/or by a bacterial protease whose maximum efficacy lies at a pH from 6 to 9;B. an effective amount of a bacterial protease having an optimum efficacy against hemoglobin at a pH above 9; andC. an effective amount of a short-chained, primary or secondary aliphatic amine.