Significance and Use
The concentration of tannins in solid, pasty, and powdered extracts needs to be reduced to analytical strength for tannin analyses.
4.2 Vegetable tannin extracts are heterogeneous mixtures of components with varying solubility.
4.3 The solubility of such extracts is influenced by temperature and concentration, which affect the degree of dispersion and size of the component particles.
4.4 Since extracts have greater solubility in hot water than cold, it is desirable to dissolve and disperse an extract in hot water and then let the solution cool slowly to standard room temperature.
It is often difficult to reduce samples of solid and particularly pasty extracts to specimen size and at the same time ensure representative sampling. Therefore, caution is advised in drawing conclusions on the precision and bias of the results obtained on such extracts; where difficulties in sample preparation are experienced, little confidence can be placed in the results.
1. Scope
1.1 This practice covers a standard procedure for use in preparing the analytical solution required for the analysis of solid, pasty, or powdered vegetable tannin extracts.
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.
ASTM Standards
D4903 Test Method for Total Solids and Water in Vegetable Tanning Material Extracts
D4904 Practice for Cooling of Analytical Solutions
D6403 Test Method for Determining Moisture in Raw and Spent Materials
D6404 Practice for Sampling Vegetable Materials Containing Tannin
ALCA Method
A11 Preparation of Solution of Solid, Pasty, and Powdered Extracts 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.
Keywords
analytical solution; tannin analysis; vegetable tannin analysis; Liquids--leather applications; Pasty tanning extracts; Powdered vegetable-tannin extracts; Preparation; Solid phase materials--leather; Specimen preparation (for testing)--leather; Tanning analysis/materials; Vegetable-tanned leather
ICS Code
DOI: 10.1520/D4905-99R09
ASTM International is a member of CrossRef.
Citing ASTM Standards
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