Method (1) for metal-free tanning of a quantity of hide having initial weight (w), said quantity of hide being contained in a drum, wherein said method (1) comprises at least one tanning treatment (B) of said hide including at least the following operating steps: B.1 feeding aliphatic aldehyde into said drum, in a percentage ranging between about 1% and 3% by weight with respect to the initial weight (w) of said hide, optionally equal to about 2% by weight, and B.2 moving said drum for a time period of at least about 10 min, optionally approximately 20 min at an operating speed between 1 and 8 revolutions/minute, preferably comprised between 4 and 5 revolutions/minute; B.3 feeding citric acid into said drum, in a percentage ranging between about 0.1% and 0.3% by weight with respect to the initial weight (w) of said hide, optionally equal to about 0.2% by weight, and B.4 moving said drum for a time period of at least about other 10 min, optionally approximately 20 min at said operating speed; B.5 feeding aliphatic aldehyde into said drum, in a percentage ranging between about 1% and about 3% by weight with respect to the initial weight (w) of said hide, optionally equal to about 2% by weight, and B.6 moving said drum for a time period of at least about 150 min, optionally approximately 180 min at said operating speed; B.7 feeding sodium formate into said drum, in a percentage ranging between about 0.3% and about 0.7% by weight with respect to the initial weight (w) of said hide, optionally equal to about 0.5% by weight, and B.8 moving said drum for a time period of at least about 20 min, optionally approximately 30 min at said operating speed; B.9 feeding magnesium oxide into said drum, in a percentage ranging between about 0.3% and about 0.7% by weight with respect to the initial weight (w) of said hide, optionally equal to about 0.5% by weight, and B.10 moving said drum for a time period of at least about 60 min, optionally approximately 90 min at said operating speed; B.11 feeding water into said drum, at a temperature ranging between about 30 C. and about 60 C., optionally equal to about 50 C., in a percentage ranging between about 30% and 50% by weight with respect to the initial weight (w) of said hide, optionally equal to about 40% by weight, and B.12 moving said drum for a time period of at least about 100 min, optionally approximately 120 min at said operating speed; B.13 feeding aliphatic aldehyde into said drum, in a percentage ranging between about 1% and 5% by weight with respect to the initial weight (w) of said hide, optionally equal to about 3% by weight, and B.14 moving said drum for a time period of at least about 100 min, optionally appro

A method for preserving hides, skins and pelts prior to tanning, without salt-curing. The hides are fatliquored, pickled and dried, all prior to tanning. The method may include the preliminary steps of washing, fleshing, liming and unhairing followed by the steps of fatliquoring, deliming, bating, pickling and drying. The method avoids the environmental damage caused by salt-curing. The treated hides are dry, flexible and readily rehydrated for further processing.

A method for preserving hides, skins and pelts prior to tanning, without salt-curing. The hides are fatliquored, pickled and dried, all prior to tanning. The method may include the preliminary steps of washing, fleshing, liming and unhairing followed by the steps of fatliquoring, deliming, bating, pickling and drying. The method avoids the environmental damage caused by salt-curing. The treated hides are dry, flexible and readily rehydrated for further processing.

A method for preserving hides, skins and pelts prior to tanning, without salt-curing. The preliminary steps of washing, fleshing, liming, unhairing, deliming and bating the hides are followed by the steps of fatliquoring, pickling and drying. The method avoids the environmental damage caused by salt-curing. The treated hides are dry, flexible and readily rehydrated for further processing.

A method for preserving hides, skins and pelts prior to tanning, without salt-curing. The preliminary steps of washing, fleshing, liming, unhairing, deliming and bating the hides are followed by the steps of fatliquoring, pickling and drying. The method avoids the environmental damage caused by salt-curing. The treated hides are dry, flexible and readily rehydrated for further processing.

The invention concerns a process for tanning hide to obtain leather. The general process for obtaining the intermediary wet blue stage comprises the following steps: a) a picking step with acid and salt, followed by b) a tanning step with chromium salt, followed by c) a basification step. The invention is characterized in that between step b) and c), a re-acidification step with organic acids is added. In particular the organic acids are selected from glutaric acid (GA), 2-methyl glutaric acid (MGA), succinic acid, ethyl succinic acid (ESA), adipic acid (AA), maleic anhydride, fumaric anhydride, tricarboxylic acids, hydroxycarboxylic acids, and mixture thereof. This invention enables an increase of the up-taking of the re-tanning products and provides leather with improved mechanical properties.

The invention concerns a process for tanning hide to obtain leather. The general process for obtaining the intermediary wet blue stage comprises the following steps: a) a picking step with acid and salt, followed by b) a tanning step with chromium salt, followed by c) a basification step. The invention is characterized in that between step b) and c), a re-acidification step with organic acids is added. In particular the organic acids are selected from glutaric acid (GA), 2-methyl glutaric acid (MGA), succinic acid, ethyl succinic acid (ESA), adipic acid (AA), maleic anhydride, fumaric anhydride, tricarboxylic acids, hydroxycarboxylic acids, and mixture thereof. This invention enables an increase of the up-taking of the re-tanning products and provides leather with improved mechanical properties.

A deliming composition and a deliming method using graft polymers from polysaccharides and/or polypeptides or the corresponding derivatives, obtainable by radical polymerization of a monomer, selected at least from, or a monomer mixture of, acrylic acid or methacrylic acid or the mixtures thereof.

A deliming composition and a deliming method using graft polymers from polysaccharides and/or polypeptides or the corresponding derivatives, obtainable by radical polymerization of a monomer, selected at least from, or a monomer mixture of, acrylic acid or methacrylic acid or the mixtures thereof.

The invention discloses a method for treating an animal substrate comprising: agitating the moistened animal substrate with a treatment formulation and a solid particulate material in a sealed apparatus wherein the treatment formulation comprises a tanning agent or a tannery process agent. The method can comprise applying the tanning agent or tannery process agent to the animal substrate wherein at least some of the agent so applied originates from the treatment formulation. There is also disclosed an animal substrate obtained by the method. The treatment formulation can be aqueous.