1、Designation: D 6716 08Standard Test Method forTotal Ash in Wet Blue or Wet White1This standard is issued under the fixed designation D 6716; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in par
2、entheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of total ash inwet blue and wet white.1.2 For total ash in wet white, the procedure is identical;substitut
3、e wet white for wet blue in the standard.1.3 Total ash in wet blue may be reported upon a number ofdifferent bases (for example, fat-free, moisture-free, as re-ceived, excluding chromium, and so forth). Before proceedingwith any tests, it is very important to determine upon whichbasis that the total
4、 ash is to be reported and to identify all othertest methods that will be required to be executed in order toachieve the determined reporting method.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This standard does not
5、purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:
6、2D 3495 Test Method for Hexane Extraction of LeatherD 6658 Test Method for Volatile Matter (Moisture) of WetBlue by Oven DryingD 6659 Practice for Sampling and Preparation of Wet Bluefor Physical and Chemical TestsD 6714 Test Method for Chromic Oxide in Ashed Wet Blue(Perchloric Acid Oxidation)3. Te
7、rminology3.1 Definitions:3.1.1 The terms and definitions employed within this testmethod are commonly used in normal laboratory practice andrequire no special comment.4. Summary of Test Method4.1 The weighed sample is ignited in air at 600 6 25C untilconstant mass is attained. The weighed residual m
8、atter istermed “ash” and is calculated as a percentage of the originalsample.5. Significance and Use5.1 This test method is useful in determining the approxi-mate amount of nonvolatile inorganic material in wet blue.This may be in the form of salts or oxides of the elements. Ina mixed-chrome tannage
9、, the approximate percentage of otherelements in the wet blue may be determined by subtracting thechromic oxide that may be conveniently determined on the ash.(See Test Method D 6714.)5.2 The specified temperature of 600C is high enough toproduce a reproducible result but it does not completelydehyd
10、rate such oxides as aluminum oxide (Al2O3) and chromicoxide (Cr2O3). Likewise, such salts as sulfates and phosphatesmay be incompletely dehydrated, and if alkalis and chromiumare present simultaneously, oxidation to chromate may occur.Therefore, caution is advised in drawing conclusions based onquan
11、titative relations of the elements.6. Apparatus6.1 Crucible, 30- to 50-mL, high-form, platinum or porce-lain.6.2 Electric Muffle Furnace, with controller or rheostat andpyrometer, capable of maintaining a temperature of 600 625C.6.3 Dessicator, of appropriate size and charged with freshdessicant.6.4
12、 Analytical Balance, capable of accurate weighings towithin 0.001 g.7. Test Specimen7.1 The specimen shall consist of 2 to 10 g of wet blue fromthe composite sample, prepared in accordance with PracticeD 6659.1This test method is under the jurisdiction of ASTM Committee D31 on Leatherand is the dire
13、ct responsibility of Subcommittee D31.02 on Wet Blue.Current edition approved Nov. 1, 2008. Published December 2008. Originallyapproved in 2001. Last previous edition approved in 2006 as D 6716 06.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service a
14、t serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NOTE 1Typically, wet blue is a combination of org
15、anic hide substancein conjunction with inorganic chromium tanning salts. However, undersome circumstances, silicones or other solvent-soluble organo-metalliccomplexes (including electrolyte-stable fat liquors) are added duringmanufacture and may be present within the sample. It may be desirable toca
16、lculate ash upon an extracted (fat free) basis, and if so, this should beindicated within the final report. To report ash upon an extracted basis, itwill be necessary to execute Test Method D 3495 on a portion of the samesample and weighed out at the same time as the specimen for total ashdeterminat
17、ion.8. Procedure8.1 Weigh accurately into a tared crucible 2 to 10 g (60.001g) of wet blue, prepared as described in 7.1, and preferably atsufficiently close equilibrium with the laboratory humidity thatit does not gain or lose mass (moisture) at a significant rate.8.2 Place the crucible and sample
18、in the muffle furnace andmaintain at 600 6 25C for at least 4 h, or longer if necessary,to destroy carbonaceous matter (Note 2).8.3 To prevent any loss of ash, very carefully remove thecrucible from the furnace, cool in a desiccator, and weigh(Note 3). Ensure that the transfer of the crucible from o
19、ven todessicator is smooth and that there are no external air draughtsthat could cause loss of ash.8.4 Replace in the furnace and maintain at 600 6 25C foranother 15 min.8.5 Repeat the weighing operation.8.6 Continue heating for 15 min and weighing as describedabove until a mass constant within 0.00
20、2 g (2 mg) is obtained.8.7 Record the final weight.NOTE 2The procedure in Section 8 is satisfactory with most wet blue.However, with wet blue that is known or suspected to have a very highgrease content or has been heavily treated with fats and oils duringprocessing, start with a cold muffle and rai
21、se temperature gradually to600C, or burn off the oil carefully over a gas burner before placing thecrucible in the hot furnace.NOTE 3If it is difficult to burn off the carbon, as evidenced byinspection or failure to achieve constant mass, moisten the ash with a fewdrops of 1:1 nitric acid, dry caref
22、ully over a low flame, and then transferto the muffle furnace and heat as before. If this procedure is unsuccessful,digest the ash in the crucible with 15 to 20 mL of hot water for a fewminutes, and filter the suspension through an ashless high-retention filterpaper. Transfer the paper and insoluble
23、 residue to the crucible and igniteat 600 6 25C as described above. Cool, add the filtrate to the crucible,evaporate carefully to dryness, then ignite at 600 6 25C to constant massas described previously.9. Calculation9.1 Calculate the percentage of ash in the wet blue weighedas follows:Ash, % 5 A B
24、! 4 C B!# 3 100where:A = weight of the ash and crucible,B = weight of the crucible, andC = weight of the sample and crucible.9.2 If it is desired to convert the percentage obtained aboveto the dry basis, perform a moisture determination (TestMethod D 6658) on a portion of the same sample weighedunde
25、r the same conditions as in Section 8. If the percentagemoisture found is D, then calculate the percentage of ash on adry basis as follows:Ash, dry basis, % 5 A B! 4 C B!# 3 100/1D/100!#where A, B, and C have the same meaning as in 9.1.10. Precision and Bias10.1 PrecisionThe precision of this test m
26、ethod is largelylimited by the homogeneity of the sample in a complex naturalmaterial such as wet blue.10.2 RepeatabilityAt the 95 % confidence level, duplicatedeterminations by the same operator should not differ by morethan 0.14 % ash.10.3 ReproducibilityAt the 95 % confidence level, theaverage of
27、 duplicate determinations in each of two laboratoriesby different operators should not differ by more than 0.20 %ash.10.4 BiasInasmuch as all wet blue contains an unknownamount of natural or inherent ash, no meaningful statement canbe made with respect to bias.11. Keywords11.1 aluminum oxide; ash; b
28、lue stock; chrome content;chromic oxide; total ash; wet blue; wet whiteASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of
29、any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are
30、 invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not rece
31、ived a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D6716082
