# ASTM D1576-13

Designation: D1576 − 13Standard Test Method forMoisture in Wool by Oven-Drying1This standard is issued under the fixed designation D1576; 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 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 the amountof moisture present in ordinary commercial and industrialsamples of wool in all forms except grease wool, using theoven-drying technique.1.2 Formulas for calculating the moisture content (as-received basis) and moisture regain (oven-dried basis) aregiven. It is always important to use the correct term whichcorresponds to the basis used in the calculation (see 12.2.1).NOTE 1—The determination of moisture content for textile materials ingeneral is covered in Test Methods D2654, and an optimal method fordetermining the moisture in wool by distillation with toluene is covered inTest Method D2462. A method for sampling wool for the determination ofmoisture in wool is covered in Practice D2525. The oven-drying methodhas been adapted for cotton in Test Method D2495.1.3 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. Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD1060 Practice for Core Sampling of Raw Wool in Packagesfor Determination of Percentage of Clean Wool FiberPresentD1776 Practice for Conditioning and Testing TextilesD2258 Practice for Sampling Yarn for TestingD2462 Test Method for Moisture in Wool by DistillationWith TolueneD2495 Test Method for Moisture in Cotton by Oven-DryingD2525 Practice for Sampling Wool for MoistureD2654 Test Method for Moisture in Textiles (Withdrawn1998)3D3333 Practice for Sampling Manufactured Staple Fibers,Sliver, or Tow for TestingD4845 Terminology Relating to Wool3. Terminology3.1 For all terminology related to D13.13, Wool and Felt,see Terminology D4845.3.1.1 The following terms are relevant to this standard:grease wool, moisture content, moisture-free, moisture regain,oven-dried, pulled wool, raw wool, recycled wool, scouredwool, virgin wool, wool, wool, as defined in the Wool ProductsLabeling Act of 1939.3.2 For definitions of all other textile terms see TerminologyD123.4. Summary of Test Method4.1 A specimen of wool material is weighed and then driedto constant mass at 105 6 2°C in an oven supplied withambient air. The loss in mass is considered moisture andreported as either moisture content or moisture regain. Direc-tions are given for the adjustment of the observed results forany change in the moisture content after sampling and beforedrying.5. Significance and Use5.1 Test Method D2462 for the determination of the mois-ture in wool by distillation with toluene is the preferred methodfor testing wool for moisture for the acceptance testing ofcommercial shipments. If, however, the purchaser and thesupplier agree, Test Method D1576 for the determination of themoisture in wool by oven drying may be used instead.Comparative tests as directed in 5.1.1, may be advisable.5.1.1 In case of a dispute arising from differences inreported test results when using Test Method D1576 foracceptance testing of commercial shipments, the purchaser andthe supplier should conduct comparative tests to determine ifthere is a statistical bias between their laboratories. Competentstatistical assistance is recommended for the investigation of1This test method is under the jurisdiction of ASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.13 on Wool and Felt.Current edition approved July 1, 2013. Published August 2013. Originallyapproved in 1958. Last previous edition approved in 2008 as D1576 – 90 (2008).DOI: 10.1520/D1576-13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at service@astm.org. For Annual Book of ASTMStandards volume information, refer to the standard’s Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1bias. As a minimum, the two parties should take a group of testspecimens which are as homogeneous as possible and whichare from a lot of material of the type in question. The testspecimens should then be randomly assigned in equal numbersto each laboratory for testing. The average results from the twolaboratories should be compared using Student’s t-test forunpaired data and an acceptable probability level chosen by thetwo parties before testing is begun. If a bias is found, either itscause must be found and corrected or the purchaser and thesupplier must agree to interpret future test results in the light ofthe known bias.5.2 This test method is a simple and convenient method forroutine process control, in-plant evaluation, estimation ofmoisture content of a lot of wool, or any other purpose forwhich a high degree of reproducibility is not necessary (seeSection 13).6. Apparatus6.1 Oven, ventilated and thermostatically controlled in thetemperature range of 105 6 2°C throughout the enclosure. Theoven may be of either the forced draft or the convection type.6.2 Weighing Containers, of perforated metal if weighing isto be performed in the drying enclosure; or containers that canbe hermetically sealed (such as glass weighing bottles) if thespecimen is to be cooled in a desiccator before weighing in theambient atmosphere.6.3 Sampling Containers, capable of being sealed. Masonjars have been found to be satisfactory where the sample sizeis not too great. For larger samples, bags of various plasticmaterials may be suitable if the wall thickness is sufficient toprovide a good moisture vapor barrier (at least 4 mil (approxi-mately 0.1 mm) for polyethylene, for example).6.4 Balance, having a capacity adequate for weighing speci-mens and containers, and a sensitivity of 0.005 g.7. Sampling7.1 Lot Sample—As a lot sample for acceptance testing,take at random the number of shipping containers directed inapplicable material specification or other agreement betweenthe purchaser and the supplier, such as an agreement to usePractice D2525 for bales of fiber and containers of top or sliveror to use Practice D2258 for beams or cases of yarn. Considershipping containers to be the primary sampling unit.NOTE 2—An adequate specification or other agreement between thepurchaser and supplier requires taking into account the variability betweenshipping containers, between laboratory sampling units within a shippingcontainer, and test specimens within a laboratory sampling unit to producea sample plan with a meaningful producer’s risk, consumer’s risk,acceptable quality level, and limiting quality level.7.2 Use extreme care to prevent gain or loss of moistureduring the sampling operation and the transfer of material tothe sampling container. Weigh each portion of the sample andits container immediately after sampling. Subtract the taremass of the container to obtain the net mass at time ofsampling, M.7.3 Laboratory Sample—As a laboratory sample for ac-ceptance testing, proceed as follows:7.3.1 For wool fiber, take laboratory samples as directed inPractice D1060 for cored samples or Practice D3333 for handsamples.7.3.2 For wool sliver or top, from each shipping container inthe lot sample, take one ball of top. From this ball of top, takeapproximately 2 m from the inside and 4 m from the outside ofthe ball.7.3.3 Take laboratory sampling units which weigh a mini-mum of 50 g. Follow the instructions in Practice D2525 forreduction of the laboratory samples to specimens.NOTE 3—Condition the laboratory samples as directed in Section 9before preparing the specimens from them.8. Number of Specimens8.1 Take a number of specimens per laboratory samplingunit that the user can expect at the 95 % probability level thatthe test result for a laboratory sampling unit will be no morethan 0.5 percentage points above or below the true average forthe laboratory sampling unit. Determine the number of speci-mens per laboratory sampling unit as follows:8.1.1 Reliable estimate of s—when there is a reliable esti-mate of s based upon extensive past records in the user’slaboratory as directed in the test method, calculate the requirednumber of specimens per laboratory sampling unit using Eq 1:n 5 ~ts/E!2 (1)where:n = number of specimens per laboratory sampling unit(rounded upward to a whole number),s = reliable estimate of the standard deviation of individualobservations on similar materials in the user’s labora-tory under conditions of single operator precision,t = the value of Student’s t for two-sided limits, a 95 %probability level, and the degrees of freedom associatedwith the estimate of v, andE = 0.5 percentage points, the allowable variation.8.1.2 No Reliable Estimate of s—When there is no reliableestimate of s for the user’s laboratory, do not use Eq 1 directly.Instead, specify the fixed number of six specimens per labora-tory sampling unit. This number of specimens per laboratorysampling unit is calculated using s = 0.60 percentage pointswhich is a somewhat larger value of s than is usually found inpractice. When a reliable estimate of s for the user’s laboratorybecomes available, Eq 1 will usually require fewer than sixspecimens per laboratory sampling unit.9. Conditioning9.1 Condition the lot sample (or laboratory sample(s)) byexposure to moving air in the laboratory atmosphere in whichthe testing is to be done, until equilibrium for testing isachieved.NOTE 4—Preconditioning and conditioning as directed in PracticeD1776 is acceptable but not necessary, since the object of the conditioningfor the purpose of this test is merely to stabilize the sample, that is, tobring all parts of the sample to moisture equilibrium with the prevailingatmosphere in order that changes in moisture level will not occur while thespecimens are being prepared and weighed.D1576 − 1329.2 Weigh the conditioned sample(s) to the nearest 0.005 gand record the net mass(es), W.NOTE 5—The net mass of the conditioned sample, W, and the net massat the time of sampling, M, will be used to convert the observed moisturecontent of the conditioned specimen to the moisture content at time ofsampling.9.3 From the weighed conditioned sample(s), take theappropriate size specimen(s) and weigh to the nearest 0.005 gto obtain the specimen mass B.10. Procedure10.1 Place the specimen(s) in the oven in a suitable con-tainer and dry to constant mass, defined as the absence of anyprogressive decrease in mass in excess of 0.10 % of theaverage as determined by three successive weighings using theprocedure in either 10.1.1 or 10.1.2 to obtain the oven-dry massof specimen, D.10.1.1 If the weighings of the dried specimen(s) are to beobtained with the specimen(s) inside the oven, perform theweighings with any forced-air circulation turned off. Space theweighings so that the drying intervals between readings will beequal to 20 % of the normal cycle with a minimum interval of5 min. Determine the normal cycle by running rate-of-dryingcurves for similar specimens using the equipment under thesame conditions that will be used for ordinary testing. Continuereadings of mass until the conditions specified in 10.1 areachieved.10.1.2 If the weighings of the dried specimen(s) are to beobtained outside the oven, dry the specimen(s) in a containerprovided with a tight-fitting cover with this cover removedwhile in the oven. At the end of the drying period, cover thecontainer and remove it from the oven. Place the coveredcontainer in a desiccator, loosen the cover, and cool thespecimen and container to approximately room temperature.When cooling is completed, set the cover firmly on thecontainer and weigh the container, cover and specimen. Re-place the container and specimen in the oven, remove thecover, and dry for an additional 30 % of the normal cycle.Repeat the cooling and weighing procedures. Continue thisprocedure until the conditions specified in 10.1 are achieved.11. Calculation11.1 Calculate to the nearest 0.01 percentage point thepercent moisture present in the sample as taken, using Eq 2 formoisture content or Eq 3 for moisture regain.Moisture content, percentage points (2)5 @1 2 ~~W 3D!/~M 3B!!# 3100Moisture regain, percentage points (3)5 @~~M 3B!/~W 3D!! 2 1# 3100where:M = net mass of subsample at time of sampling,W = net mass of subsample at time of measurement,B = net mass of specimen before drying, andD = oven-dry mass of specimen.11.2 Calculate the average moisture content (or moistureregain) of all specimens tested for one lot to the nearest 0.1percentage point.11.3 The following equations may be used to convertmoisture regain in percentage points to moisture content inpercentage points and vice versa:R 5 @C/~100 2 C!# 3100 (4)C 5 @R/~1001R!# 3100 (5)where:R = moisture regain, percentage points, andC = moisture content, percentage points.12. Report12.1 State that the specimens were tested as directed in TestMethod D1576. Describe the material or product sampled andstate the method of sampling used.12.2 Report the following information:12.2.1 The average value of the results calculated for aparticular lot to the nearest 0.1 percentage point, statingwhether the reported value is the moisture content or themoisture regain.12.2.2 The number of specimens tested.12.2.3 The range of the moisture contents or moistureregains (difference between the largest and smallest observedresults).13. Precision and Bias13.1 Interlaboratory Test Data4—An interlaboratory testwas carried out in 1963 in which 4 laboratories tested 12specimens each of a nominally uniform wool material formoisture content. The components of variance expressed asstandard deviations were calculated to be:Within-laboratory componentBetween-laboratory component0.236 percentage point0.469 percentage point13.1.1 The within-laboratory component includes thesingle-operator component which was not determined sepa-rately. The components listed above do not include anysampling error. This error must be added in any application ofthe method.4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D13-1016 .D1576 − 13313.2 Precision—For the components of variance reported in13.1, two averages of observed values should be consideredsignificantly different at the 95 % probability level if thedifference equals or exceeds the critical differences listedbelow:Critical Differences, PercentagePoints, for the Conditions NotedA,BNumber of Within- Between-Observat