1、Designation: D 6716 06Standard Test Method forTotal Ash in Wet Blue1This 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 parentheses indi
2、cates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of total ash inwet blue.1.2 Total ash in wet blue may be reported upon a number ofdifferent bases (for example, fat-fr
3、ee, 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 ash is to be reported and to identify all othertest methods that will be required to be executed in order toachieve the determined rep
4、orting method.1.3 This standard does not 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
5、. Referenced Documents2.1 ASTM Standards: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
6、 Wet Blue(Perchloric Acid Oxidation)3. Terminology3.1 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
7、 mass is attained. The weighed residual matter 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
8、of the elements. Ina mixed-chrome tannage, 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 reproducib
9、le result but it does not completelydehydrate 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 ad
10、vised in drawing conclusions based onquantitative 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
11、 size and charged with freshdessicant.6.4 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 AST
12、M Committee D31 on Leatherand is the direct responsibility of Subcommittee D31.02 on Blue Stock.Current edition approved Oct. 1, 2006. Published November 2006. Originallyapproved in 2001. Last previous edition approved in 2001 as D 6716 01.2For referenced ASTM standards, visit the ASTM website, www.
13、astm.org, orcontact ASTM Customer Service at 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 1
14、Typically, wet blue is a combination of organic 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
15、within the sample. It may be desirable tocalculate 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 t
16、ime as the specimen for total ashdetermination.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 signific
17、ant rate.8.2 Place the crucible and sample 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). Ensu
18、re that the transfer of the crucible from oven 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 descr
19、ibedabove until a mass constant within 0.002 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 duringp
20、rocessing, start with a cold muffle and raise 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 wi
21、th a fewdrops of 1:1 nitric acid, dry carefully 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 fi
22、lterpaper. Transfer the paper and insoluble 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
23、the wet blue weighedas follows:Ash, % 5 A B! 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)
24、on a portion of the same sample weighedunder 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 Bia
25、s10.1 PrecisionThe precision of this test method 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 Reproducibility
26、At the 95 % confidence level, theaverage of 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 b
27、ias.11. Keywords11.1 aluminum oxide; ash; blue stock; chrome content;chromic oxide; total ash; wet blueASTM 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 d
28、etermination of the validity of 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
29、 or withdrawn. Your comments are 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
30、that your comments have not received 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).D6716062
