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Significance and Use
This test method is used to determine the chemical properties of tannery liquors which are relevant for the vegetable tanning process and influence the astringency of vegetable tanning liquors. The astringency of liquors is dependent upon the solids and tannin content and the acidity. This method provides a standard procedure for determining these properties for any sample of vegetable tanning liquor.
The specimens are aliquots from the analytical solution prepared from the sample of tannery liquor collected for this purpose.
The total solids, soluble solids, and non-tannins content are determined and then the tannin content of the liquor sample is calculated. Because the amount of tannin per liter of analytical solution is less than that required for Test Method D 6401
The total acidity of the liquor sample is determined by one of two titrametric procedures described in Test Method D 6410
The results of this test method are dependent on a great many variables but particularly upon: the temperature conditions under which the solutions were prepared and stored and the temperature at which the current analysis is performed; the uniformity and consistency of the Kaolin paste layer deposited onto the filter paper; the rate of solution run-out from the pipette; conditions related to the properties of the hide powder used to react with the tannin content of the solution; etc. It is, therefore, essential that the method be followed exactly in order to obtain reproducible results both among specimens within a laboratory and for analyses between laboratories.
1.1 This test method covers the analysis of tannery liquors made up from vegetable tanning materials.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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 appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
D4903 Test Method for Total Solids and Water in Vegetable Tanning Material Extracts
D4904 Practice for Cooling of Analytical Solutions
D6401 Test Method for Determining Non-Tannins and Tannin in Extracts of Vegetable Tanning Materials
D6402 Test Method for Determining Soluble Solids and Insolubles in Extracts of Vegetable Tanning Materials
D6404 Practice for Sampling Vegetable Materials Containing Tannin
D6410 Test Method for Determining Acidity of Vegetable Tanning Liquors
ALCA MethodsA25 Analysis of Tannery Liquors Official Methods of the American Leather Chemists Association. Available from the American Leather Chemists Association, University of Cincinnati, P.O. Box 210014, Cincinnati, OH 45221-0014.
ICS Number Code 59.140.10 (Processes and auxiliary materials)
UNSPSC Code 31221603(Organic tanning extracts of vegetable origin)