ASTM D6409-99(R2020) pdf free download

ASTM D6409-99(R2020) pdf free download.Standard Practice for Color Tests with Sheepskin Skiver
1. Scope
1.1 This practice covers making color tests of all types of vegetable tanning extracts and of vegetable tanning materials to determine the color imparted to tanned skins. 1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.4 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
3. Terminology
3.1 Definitions: 3.1.1 For definitions of general leather and tanning terms used in this practice refer to Terminology D1517. 3.1.2 pickled skiver—a sheepskin skiver that has been pick- led in a solution of salt and sulfuric acid. 3.1.3 sheepskin skiver—the grain split of a de-wooled sheepskin. A pickled skiver is used for this test. 3.1.4 tannin—an astringent substance found in the various parts of plants such as bark, wood, leaves, nuts, fruits, roots, etc. 3.1.5 vegetable tannins—mixtures of substances (natural products) obtained from plant tissues by water extraction which have the chemical and physical properties necessary to convert animal hides and skins into leather.
4. Summary of Practice
4.1 A specimen of pickled skiver is tanned with a sample of vegetable tanning liquor in order to determine the color which will be imparted to a clear, clean hide or skin that is tanned with this tanning liquor.
5. Significance and Use
5.1 This practice provides a standard procedure for compar- ing the color ofleather tanned with different tanning extracts or mixtures of extracts or for monitoring the color consistency of tannery liquors.
6. Apparatus and Reagents
6.1 Pickled Sheepskin Skiver, specially and consistently selected for the color test. 6.2 Borax, commercial grade such as may be used in a tannery. 6.3 Containers, 10 and 3 L capacity and made of suitable material to be resistant to the chemicals and materials used in the tanning procedure employed by this practice. 6.4 Acetic Acid, glacial, commercial grade. 6.5 Sodium Acetate, crystal, commercial grade. 6.6 Sodium Chloride, crystal, commercial grade. 6.7 Shake Bottles, 0.95 L (32 oz), with rubber stoppers. The bottles shall be approximately 21.6 cm (8.5 in.) overall height and 8.9 cm (3.5 in.) diameter. One quart canning jars (Mason- type) with plastic screw-on lids work well. 6.8 Shaking Machine, rotating type, equipped to hold 0.95 L (32 oz) bottles for end-over-end agitation of hide powder and analytical solution. The speed of rotation shall be 606 2 rpm, and the machine shall be so constructed that the side of the shake bottle adjacent to the rotating shaft shall be not less than 5.1 cm (2 in.) nor more than 7.6 cm (3 in.) from the center of the shaft. 6.9 Flat Dish, 250 to 300 mL capacity; a photographic tray works well. 6.10 Rubber Roller, photographic print roller works well.
8. Preparation of Skiver
8.1 The neck and flank portions of the skiver shall be trimmed off, leaving a skin of uniform grain. The skiver may now be cut into pieces approximately 10 by 15 cm (4 by 6 in.) or may be left whole. The skiver shall be placed in a solution of 50 g of borax dissolved in 8 L of distilled water and at a temperature of 23 to 25 °C. It shall be stirred, or agitated, frequently and, at the end of4 h, be transferred to a fresh borax solution, made up as before, be stirred several times and then allowed to remain overnight therein at not less than 23 °C nor more than 28 °C. Next morning, the skiver shall be transferred to 8 L of a 0.1 % solution of acetic acid, at 23 to 25 °C, be stirred, or agitated, frequently and, at the end of 3 h, be placed in a fresh solution of acetic acid of the same volume, strength, and temperature, and be stirred, or agitated, frequently. At the end of 3 h, the skiver shall be placed in 2 L of an acetic acid/sodium acetate buffer solution, at 23 to 25 °C, containing 2.0 g glacial acetic acid and 10 g ofsodium acetate crystals per litre, and having a pH of 4.8 to 5.0. The skiver shall be stirred in this solution several times and then allowed to remain therein overnight. Next morning, the skiver shall be transferred to a saturated solution of sodium chloride containing a large excess of the salt.