IULTCS - International Union of Leather Technologists and Chemists Societies

This document specifies a method for determining the dry or wet flex resistance of leather and finishes applied to leather. It is applicable to all types of flexible leather below 3,0 mm in thickness.

This document specifies a chromatographic method to determine the amount of middle-chain chlorinated paraffins (MCCPs) C14 to C17 in processed and unprocessed leathers.

This document specifies a chromatographic method to determine the amount of short-chain chlorinated paraffins (SCCPs) C10 to C13 in processed and unprocessed leathers.

This document specifies a method of determining the dimensional change (shrinkage) of leathers caused by ageing. It is applicable to all leathers.

This document specifies a method for the determination of free formaldehyde, which is released under dynamic conditions when the sample is heated in an inert dry atmosphere, in process auxiliaries for leather. The analytical result obtained according to this procedure is expressed in milligrams per kilogram (mg/kg) sample.

This document specifies a method for the determination of free and released formaldehyde in leathers. This method, based on high-performance liquid chromatography (HPLC), is selective and not sensitive to coloured extracts and is intended to be used for precise quantification of formaldehyde. The formaldehyde content is taken to be the quantity of free formaldehyde and formaldehyde extracted through hydrolysis contained in a water extract from the leather under standard conditions of use.

This document specifies a method for determining the use of certain azo colourants which can release certain aromatic amines.

This document specifies a test method by artificial perspiration solution aqueous extraction for the determination of the aqueous extractable content of the following preservative agents in leather by liquid chromatography: — 2-(thiocyanomethylthio)-benzothiazole (TCMTB); — 4-chloro-3-methylphenol (PCMC); — 2-phenylphenol (OPP); — 2-octylisothiazol-3(2H)-one (OIT); This method can also be used to determine breakdown products of these preservative agents, which protect leather from microbiological attack.

This document specifies a test method by acetonitrile solvent extraction for the determination of the total content (solvent extractible) of the following preservative agents in leather by liquid chromatography: — 2-(thiocyanomethylthio)-benzothiazole (TCMTB); — 4-chloro-3-methylphenol (PCMC); — 2-phenylphenol (OPP); — 2-octylisothiazol-3(2H)-one (OIT); This method can also be used to determine breakdown products of these preservative agents, which protect leather from microbiological attack.

This document specifies a test method to determine the degree and rate of aerobic biodegradation of hides and skins of different animal origin, whether they are tanned or not, through the indirect determination of CO2 produced by the degradation of collagen. The test material is exposed to an inoculum (activated sludge from tannery wastewater) in an aqueous medium. If there is not a tannery nearby then urban wastewater can be used as the inoculum. The conditions established in this document correspond to optimum laboratory conditions to achieve the maximum level of biodegradation. However, they might not necessarily correspond to the optimum conditions or maximum level of biodegradation in the natural medium. In general, the experimental procedure covers the determination of the degradation degree and rate of the material under controlled conditions, which allows the analysis of the evolved carbon dioxide produced throughout the test. For this purpose, the testing equipment complies with strict requirements with regard to flow, temperature and agitation control. This method applies to the following materials: — natural polymers of animal stroma (animal tissue/skins); — animal hides and skins tanned (leather) using organic or inorganic tanning agents; — leathers that, under testing conditions, do not inhibit the activity of microorganisms present in the inoculum.

This document specifies a method for determining the tensile strength, elongation at a specified load and elongation at maximum force of leather. It is applicable to all types of leather.

This document specifies a method using microscopy to identify leather and distinguish it from other materials. The method is not applicable for identifying specific leathers (e.g. sheep leather).

This document specifies a test method for the determination of tanning agents through filtration of all vegetable and synthetic tanning products.

This document specifies a method of determining the abrasion resistance of leather using a Taber® apparatus.

This document specifies a method for determining alkylphenols (nonylphenol and octylphenol) and alkylphenol ethoxylates (nonylphenol ethoxylate and octylphenol ethoxylate) in leather and process auxiliaries. The analysis is based on high-performance liquid chromatography (HPLC) or gas chromatography-mass spectrometry (GC-MS). The analysis of the alkylphenol ethoxylate is made by cleaving the alkylphenol ethoxylate and measuring the released alkylphenol. NOTE ISO 18218-1 and this document use different solvents for the extraction of the ethoxylated alkylphenols from leather. Consequently, the two analytical methods are expected to give similar trends but not necessarily the same absolute result for the ethoxylated alkylphenol content in leather.

This document specifies a method for determining the stitch tear resistance of leather. It can be used on all leathers but is particularly suitable for leathers over 1,2 mm in thickness.

This document specifies a quantitative test method to determine 24 kinds of pesticide residues in leather by gas chromatography-mass spectrometry (GC-MS). This document is applicable to all types of leather that could release pesticides.

This document specifies a method for determining the resistance of all forms of leather to visible soiling through repeated contact with soiled objects. It provides a physical pretreatment routine for leathers that may be vulnerable to loss of soiling resistance while in service, prior to conducting further tests such as cleaning.

This document specifies a method for the correct measurement of the colour of finished leather by instrumental means. The document describes general concepts of colour measurement adapted to leather and the calculation of differences in colour. This document defines the following: a) the use of D65 as the standard light source for the leather industry; b) the use of D65 light source 10° as standard conditions for colour matching, for the definition of daylight simulators and as the reference light source for metamerism analysis; c) the use of CIEDE2000 as the colour difference formula.

This document specifies a method for the determination of extractable metals in leather using extraction with an acid artificial-perspiration solution and subsequent determination with inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), atomic absorption spectrometry (AAS) or spectrometry of atomic fluorescence (SFA). This method determines extractable metals in leather; it is not compound-specific or specific to the oxidation state of the metals. This method is especially suitable for determining the extractable chromium in chromium-tanned leathers.

This document specifies a method for the determination of the total metal content in leather using digestion of the leather and subsequent determination with inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), atomic absorption spectrometry (AAS) or spectrometry of atomic fluorescence (SFA). This method determines the total metal content in leather; it is not compound-specific or specific to the oxidation state of the metals.

This document specifies a method for the determination of free and released formaldehyde in leathers. This method, based on colorimetric analysis, is not intended to be used for a precise quantification of formaldehyde. The formaldehyde content is taken to be the quantity of free-formaldehyde and formaldehyde extracted through hydrolysis contained in a water extract from the leather under standard conditions. This process is not absolutely selective for formaldehyde. Other compounds such as extracted dyes could interfere at 412 nm.

This document describes a method for the determination of chromium in aqueous solution obtained from leather. This is an analysis for total chromium in leather; it is not compound specific or specific to its oxidation state. This method describes the determination of chromium by inductively coupled plasma (ICP) and is applicable to leathers which are expected to have chromic oxide contents in excess of 1 mg/kg. Two techniques for the preparation of the solution to be analysed are included. In the event of dispute, the wet oxidation technique is intended to be used.

This document specifies a test method for detection and quantification of extractable neutral, ionic, long, medium and short chain perfluorinated and poly-fluorinated substances in leather and coated leather. This document, taking into account the three-dimensional distribution of the fibres within leather, makes the evaluation of the perfluorinated and poly-fluorinated substances with respect to the mass. Classes of regulated compounds listed in Annex A, Table A.1, include acids, telomers, sulfonates and sulphonamide alcohols. Classes of other non-regulated compounds that can be determined by this document are defined in Annex B, Table B.1.

This document specifies a method for determining the behaviour of the surface of a leather on rubbing with a wool felt. It is applicable to leathers of all kinds.

This document specifies a method for the determination of the substances in leather which are soluble in dichloromethane. This method is applicable to all types of leather. Not all fatty and similar substances can be extracted from leather with organic solvents; they may be in part soluble and partly bound to the leather. On the other hand, the solvent can dissolve non-fatty substances, for example sulfur and impregnants, both of which cause difficulty in the determination of the acid value and saponification value of the fat. This document includes two techniques for extraction of the fatty substances: 1) extraction using the Soxhlet apparatus; and 2) extraction using a pressurized extraction system. As the extraction is frequently done in conjunction with determination of the free fatty acid content of the leather, a suitable procedure for determination of the free fatty acids extracted by this method is included. The apparatus and technique described in this method are also suitable for the extraction by solvents other than dichloromethane (although the temperature conditions may need to be varied for high pressure extraction).

This document describes a method for the determination of chromium in aqueous solution obtained from leather. This is an analysis for total chromium in leather; it is not compound specific or specific to its oxidation state. This method describes the determination of chromium by atomic absorption spectrometry and is applicable to leathers which are expected to have chromic oxide contents in excess of 5 mg/kg. Two techniques for the preparation of the solution to be analysed are included. In the case of disputes, the wet oxidation technique is to be used.

This document describes a method for the determination of chromium in aqueous solution obtained from leather. This is an analysis for total chromium in leather; it is not compound specific or specific to its oxidation state. This method describes the determination of chrome by iodometric titration and is to be applicable to chromium-tanned leathers which are expected to have chromic oxide contents in excess of 0,3 %. Two different methods are described as alternatives for obtaining chromium in a suitable solution. It is appropriate to use either method.

This document specifies a thermal pre-ageing procedure for leather to obtain indications about the tendency to the formation of hexavalent chromium under specified conditions and the determination of hexavalent chromium according to ISO 17075‑1 or ISO 17075‑2. This thermal pre-ageing procedure does not simulate any real condition in leather production or use. It is applicable to all types of chromium tanned leather.

This document specifies a method for determining the pH value and the difference figure of an aqueous leather extract. It is applicable to all types of leather.

ISO 4098 | IULTCS/IUC 6:2018 specifies a method of determination of water-soluble matter, water-soluble inorganic matter and water-soluble organic matter. ISO 4098 | IULTCS/IUC 6:2018 is applicable to all leather types. The result obtained by this analysis depends on factors such as: - the degree to which the leather is ground; - the extraction temperature; - the extraction period; - the ratio of leather to water. To obtain comparable results, it is consequently imperative that test conditions be accurately reproduced. In all cases, any ammonium salts in the filtrate are included as part of the water-soluble matter and are then decomposed on ignition. Thus they contribute towards the result for water-soluble organic substances. The concentration of the ammonium salts can be determined in the filtrate separately if required.

ISO 20701 | IUF 427:2017 specifies a method for determining the colour fastness to saliva of all kinds of leathers, independent of the colouring procedure applied. The method uses an artificial saliva solution to simulate whether colouring materials can migrate from leather to the mouth or to the mucous membranes.

ISO 17231 | IULTCS/IUP 37:2017 specifies a method for determining the repellency of leather to surface wetting. It is applicable to all leathers intended for use in clothing. The method does not determine the resistance of leather to water penetration.

ISO 20137:2017 gives guidelines to apply the available chemical test methods for leather. This information can be used by those involved in setting specifications for leather, especially for those parameters relating to restricted chemical substances. Lists of restricted chemicals contain many substances that are not relevant to the leather industry. Those chemical substances that are not mentioned in this document do not need to be determined, thus avoiding unnecessary analytical costs.

ISO 17075-2:2017 specifies a method for determining chromium(VI) in solutions leached from leather under defined conditions. The method described is suitable to quantify the chromium(VI) content in leathers down to 3 mg/kg. ISO 17075-2:2017 is applicable to all leather types. The results obtained from this method are strictly dependent on the extraction conditions. Results obtained by using other extraction procedures (extraction solution, pH, extraction time, etc.) are not comparable with the results produced by the procedure described in this document. If a leather sample is tested with both ISO 17075-1 and this document, the results obtained with this document are considered as the reference. The advantage of the method described in this document is that there are no interferences from the colour of the extract. Nevertheless, interlaboratory trials do not show significant differences (see Annex D) and the results are comparable between both methods.

ISO 17075-1:2017 specifies a method for determining chromium(VI) in solutions leached from leather under defined conditions. The method described is suitable to quantify the chromium(VI) content in leathers down to 3 mg/kg. ISO 17075-1:2017 is applicable to all leather types. The results obtained from this method are strictly dependent on the extraction conditions. Results obtained by using other extraction procedures (extraction solution, pH, extraction time, etc.) are not comparable with the results produced by the procedure described in this document. If a leather sample is tested with both this document and ISO 17075-2, the results obtained with ISO 17075-2 are considered as the reference. The advantage of the method described in ISO 17075-2 is that there are no interferences from the colour of the extract. Nevertheless, interlaboratory trials do not show significant differences (see Annex C) and the results are comparable between both methods.

ISO 2418:2017 specifies the location of a laboratory sample within a piece of leather and the method of labelling and marking the laboratory samples for future identification. It is applicable to all types of leather derived from mammals irrespective of the tanning used. It is not applicable to leathers derived from birds, fish, reptiles or furs.

ISO 2420:2017 specifies a method for determining the apparent density and the mass per unit area of leather. It is applicable to all leathers.

ISO 17232:2017 specifies two methods for determining the heat resistance of patent leather. Method A makes use of a modified lastometer, while Method B uses the "Zwik" apparatus. Both methods are applicable to patent leathers for all end uses.

ISO 17233:2017 specifies a method for determining the cold crack temperature of surface coatings applied to leather. It is applicable to all leathers which have a surface coating and which can be easily flexed.

ISO 4044:2017 specifies how to prepare a test sample of leather for chemical analysis. The test sample can be either ground or cut into small pieces. Unless specified in this document, the method to be used depends on the size of leather sample available for testing.

ISO 19076:2016 provides a method for the measurement of the surface of leather or leather parts by the use of electronic measuring machines. It applies to the measurement of leather (or leather parts) fulfilling the following requirements: - flexible leather, finished or unfinished, dry or wet leather; - flexibility: such to allow full distension on the measuring line/surface.

ISO 19071:2016 specifies a test method for the determination of chromium (VI) content in chromium tanning agents. The results give information about the reductive potential of the chromium tanning agent.

ISO 19070:2016 specifies a method to determine the amount of N-methyl-2-pyrrolidone (NMP) in leather and leather components. This method may also be used for the determination of N-ethyl-2-pyrrolidone (NEP) in leather.

ISO 3377-2:2016 specifies a method for determining the tear strength of leather using a double edged tear. The method is sometimes described as the Baumann tear. It is applicable to all types of leather.

ISO 2417:2016 specifies a method for determining the water absorption of leather under static conditions. The method is applicable to all leather, particularly heavy leather.

ISO 2589:2016 specifies a method for determining the thickness of leather. The method is applicable to all types of leather of any tannage. The measurement is valid for both the whole leather and a test sample.

ISO 17236:2016 specifies a method for determining the extension set of leather. It is intended for use on upholstery leather but is applicable to all flexible leathers.

ISO 17229:2016 specifies a method for determining the water vapour absorption of leather. The method is applicable for all leathers but is particularly relevant for leathers intended for footwear uppers and linings.

ISO 5402-2:2015 specifies a method for determining the wet or dry flex resistance of leather and finishes applied to leather. It is applicable to all types of leather below 3,0 mm in thickness.