Leather test methods

American Leather Chemists Association c/o University of Cincinnati Cincinnati, Ohio 45221 Chemical and physical test methods for leather... 

Test Methods. Tests for measuting the water and oU repeUency of leather iaclude ASTM and AATCC tests, as weU as tests developed by suppUers. 

In OU RepeUency (AATCC Test Method 118), drops of oUs of various surface tensions are placed on the leather and monitored to absorption (14). 

Tests Simulating Use Conditions. Several simulation tests involving wear and use testing have been developed. The first and only one to be adopted as a standard in the United States is AATCC Test Method 134-1975 for measuring the electrostatic propensity of carpets (60). In this test a person wearing standard neoprene and leather sole shoes and carrying a probe connected to an electrometer walks on a carpet for 30 to 60 s until the measured body voltage builds up to a maximum. 

D 1611 1981 (1986) Test method for corrosion produced by leather in contact with metal... 

ASTM D2214, 2002. Standard test method for estimating the thermal conductivity of leather with the Cenco-Fitch apparatus. 

The complete and systematic examination of leather, including physical and mechanical tests 1 and chemical analysis, is carried out principally for tannin- or chrome-tanned leathers. The methods to be used in this examination arc given below and are preceded by the procedure to be followed in sampling. 

More and more products made from synthetic materials substituting for leather have been introduced into the market. S ynthetic leather substitutes are usually nonwoven fabrics coated or laminated with some kind of polymer. It is very often desired to identify if a product is a genuine leather or a synthetic substitute. The following four test methods can be used to identify the samples. 

Leather is a natural product and is subject to extensive variability. The physical and chemical properties vary considerably depending on the location from which the leather test sample is taken. The standard test method from the American Society for Testing and Materials (ASTM D2813, 1997) ensures random sampling of finished leather and fabricated leather items for physical and chemical tests. Test specimens should be cut from only one side of the backbone with their long dimension perpendicular to the backbone line. Test specimens should be taken from different parts of the shoulder, belly and tail of the leather. The number of specimens taken depends on the reliability of the test results, the deviation and the error of the testing procedures and should be recorded on the test report. Physical tests of leather and leather products, unless otherwise specified, should be performed under the standard atmospheric conditions of 50 4% relative humidity at 23 1 °C. 

Total ash content in leather can be measured by the standard test methods ASTM D2617-96 or by thermogravimetric analysis (TGA). 

Cut-resistance is an important property of leather against mechanical forces, especially for products that are more at risk of cutting such as gloves, shoes or sport goods. The test method is to measure the force needed to cut through the sample at a distance of 20 mm (International Organization for Standardization, ISO, 1999). 

American Leather Chemists Association (ALCA) (1954a), ALCA Test Method A22, Nontannins and Tannins in Vegetable-Tannins Extracts, Lubbock, Texas, ALCA. 

American Society for Testing and Materials (ASTM) (1998), ASTM D28O7 Standard Test Method for Chromic Oxide in Leather (Perchloric Acid Oxidation). West Conshohocken, PA (reapproved 1998), ASTM. 

Standard Test Method for Corrosion Produced by Leather in Contact with Metal Standard Test Method for Evaluation of Painted or Coated Specimens Subjected to Corrosive Environments... 

Crocking This is a jargon term for tendency for color to mb off onto other objects. The testing procedures used are based on those specified for textiles by the American Association of Textile Colorists and Chemists (AATCC, www.aatcc.org) Test Methods 8 and 116. A piece of white, unsized fabric is mbbed across the plastic surface under constant pressure. After the specified number of mbs, the fabric is examined visually or colorimetrically for color pickup. The equipment is referred to as a Crockmeter. With flexible PVC articles, it is also possible to adapt the procedure of ASTM D5053, originally designed for use with leather. 

The primary purpose of the test methods is to ensure that the finished leathers are as a whole suitable for the stated purpose. Accordingly, many test methods simulate the stresses to which the finished leathers are exposed in use. It must always be noted in this context that the leather itself has a substantial influence on the tests as well as the finish coat on the leather. The different leather types vary greatly in thickness, softness, surface stracture, hydrophilicity, etc. Even a single hide is not homogeneous in itself For example, fiber density, leather thickness, pore structure and absorbency are different in the beUy than in the butt. For this reason, the corresponding test descriptions (e.g., DIN or ISO standards) provide precise definitions of the areas of the leather from which the test specimens are to be taken. The test results... 

Since finished leathers are predominantly used in the shoe industry, test methods are largely adapted to these requirements. From experience, these test methods are also suitable for evaluating other leather articles such as upholstery leather, apparel leather and leather for bags and suitcases. The fastness level to be achieved varies from article to article. 

The International Union of Leather Technologists and Chemists Societies has developed, mostly binding, Methods of chemical leather analysis (I.U.C. methods) and Methods of physical leather testing (I.U.P. methods). The German DIN sheets for testing leather have in most cases been conformed to the above methods. I.U.F. (International Union Fastness) describes guidelines and test methods drawn up by the International Fastness Commission for leather dyes and dyed leathers. 

The following methods are only the most important tests in common use. In addition, there are a multiplicity of specific test methods, either designed for certain leather articles or required by certain customers. 

Seed germination. Tests for allelochemical Inhibition of wild mustard [Brasslca kaber (DC.) L.C. Wheeler var. plnnatlflda (Stokes) L.C. Wheeler] seed germination were made according to the methods of Leather (3). Germination of white clover (Trlfollum... 

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