ASTM D7477-16(2021)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7477 − 16 (Reapproved 2021)
Standard Test Method for
Determining the Area Stability of Wet Blue Submersed in
Boiling Water
This standard is issued under the fixed designation D7477; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope or until it is completely re-hydrated (see 9.1 for details on
re-hydration). The specimen to be tested is cut out from this
1.1 This test method provides a standard procedure for
thoroughly hydrated sample cutting. The test specimen is then
determination of the dimensional stability or area shrinkage of
totally submerged and suspended in boiling water. The test
a specimen of Wet Blue that is submersed in boiling water for
specimen is removed 3.0 min after the water temperature
a specified time period. This test method is applicable to all
reaches 100 °C and begins to re-boil.As soon as the specimen
types of Wet Blue.
has cooled sufficiently to allow comfortable handling the area
1.2 The values given in SI units are to be regarded as the
loss is determined.
standard. The inch-pound units given in parentheses are for
information only.
4. Significance and Use
1.3 This test method does not apply to Wet White.
4.1 Determinationofthehydro-thermalareastabilityofWet
1.4 This standard does not purport to address all of the
Blue provides information concerning the efficacy of the
safety concerns, if any, associated with its use. It is the
tanning process as well as the adequacy of the Wet Blue for
responsibility of the user of this standard to establish appro-
intended end use applications where area stability is a particu-
priate safety, health, and environmental practices and deter-
lar requirement. Relative area stability of chrome-tanned
mine the applicability of regulatory limitations prior to use.
leather is a requirement for many applications such as
1.5 This international standard was developed in accor-
bookbinding, shoe and boot components, upholstery, seals and
dance with internationally recognized principles on standard-
gaskets, etc.
ization established in the Decision on Principles for the
4.2 Thistestmethodissuitableforuseindevelopmentwork
Development of International Standards, Guides and Recom-
and process control in the tannery and for specification testing
mendations issued by the World Trade Organization Technical
of Wet Blue for domestic and international commercial pur-
Barriers to Trade (TBT) Committee.
poses.
2. Referenced Documents
2 5. Apparatus
2.1 ASTM Standards:
D6659Practice for Sampling and Preparation of Wet Blue
5.1 Beaker, standard, IL capacity. Other suitable containers
and Wet White for Physical and Chemical Tests may be used so long as the dimensions are sufficiently large to
E691Practice for Conducting an Interlaboratory Study to
enable suspension of the completely immersed test specimen
Determine the Precision of a Test Method with no contact occurring with the sides and bottom of the
E177Practice for Use of the Terms Precision and Bias in container during the test. Particularly when non-standard test
ASTM Test Methods specimens are used, the size and shape requirements of the
container are dependent on the dimensions of the specimen to
3. Summary of Test Method
be tested.
3.1 AsamplecuttingofWetBlueiseithertakendirectlyout
5.2 Thermometer, with a minimum scale reading to +110
of the tanning drum or else is pre-soaked in water for 30 min
°C, graduated in 1 °C, and having a 0.5 °C tolerance.
5.3 Timer, with minimum 3 min capacity and 1.0 s resolu-
This test method is under the jurisdiction ofASTM Committee D31 on Leather
and is the direct responsibility of Subcommittee D31.02 on Wet Blue.
tion.
Current edition approved Sept. 1, 2021. Published October 2021. Originally
5.4 Metal die, to cut specimens. The die should be con-
approved in 2008. Last previous edition approved in 2016 as D7477- 16. DOI:
10.1520/D7477-16R21.
structed of highly corrosion resistant alloy metal and must be
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
maintained in a clean and sharp condition to minimize distor-
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
tion of the Wet Blue sample that may occur during the
Standards volume information, refer to the standard’s Document Summary page on
theASTM website. specimen cutting operation. The recommended specimen is a
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7477 − 16 (2021)
(actual measurement after the test was 94 mm determined by averaging
square76.2by76.2mm(3.00by3.00in.).However,othersize
the measured length of the two edges parallel to that dimension) then the
and shape specimens can be used so long as the requirements
approximate area loss for that specimen would be 10 % (that is,4+6%).
of Section 8 are met.
However, multiplication and subtraction followed by division [(10 000 –
2 2
9024 mm )/10 000 mm ] yields 9.76 % for the actual area loss. For most
5.5 Measuring scale, ruler longer than the greatest dimen-
applications using this method, the area loss determined by simply adding
sion of the test specimen, divided in millimeters ( ⁄32 in.).
the dimensional loss values will give adequate results without going
5.6 Marking pen, Suitable water-proof marker or pen for through the mathematical calculations.
marking the indicator points, on the hydrated Wet Blue grain
8.3 Appropriate small holes may be punched in the test
surface, to be used for measuring the specimen dimensions.
specimen to facilitate the suspension of the submerged speci-
meninthebeakerofwaterduringthetestifJ-hooksorS-hooks
6. Reagents and Materials
are used in conjunction with a rod across the top of the beaker.
6.1 Water, distilled or de-ionized laboratory water should be
Alternative practices may provide suspension of the specimen
used, especially if there is any possibility of constituents in the
by employing a net type structure attached to a rod across the
available tap water affecting the results of this test.
top of the beaker.
6.2 Glycerin (Glycerol), technical grade is adequate.
9. Procedure
6.3 Salt (Sodium Chloride), common table salt is adequate.
9.1 Cuttings that are taken directly out of the tanning drum
prior to dumping and wringing need not be re-hydrated.
7. Hazards
Thorough hydration of the original sample cutting taken from
7.1 Allreagentsandchemicalsshouldbehandledwithcare.
Wet Blue after wringing shall be ensured by pre-soaking this
Before using any chemical, read and follow all safety precau-
cuttingforaminimum30minoruntilthecuttingiscompletely
tions and instructions on the manufacturer’s label or MSDS
re-hydrated. All soaking for re-hydration should take place
(Material Safety Data Sheet).
under ambient temperature conditions at the testing location.
Cuttings taken fromWet Blue after wringing and that have not
8. Test Specimen
dried out usually re-hydrate within 30 min. Wet blue cuttings
8.1 Theoriginalsamplecuttingtobepre-soakedandthetest
that have dried out somewhat may require significantly more
specimen cut from it shall be taken from the Wet Blue
than 30 min to become completely re-hydrated. Wet blue
accordingtoPracticeD6659.Specifically,forahideorsidethe
cuttings that have become significantly air-dried may require
cutting shall be taken from the “a” test area (the kidney area)
soaking periods as long as overnight to re-hydrate completely.
of a hide or side. The number of samples to be tested shall be
Re-hydration of the sample cutting can be accomplished by
as described in Practice D6659 and need not be more than 12
soaking in a container or tray so long as the cutting is
per 50 000 ft of Wet Blue stock.
completely covered with water. Bending or flexing the cutting
8.2 The sample cutting taken from the Wet Blue should be
while it is completely immersed in water or application of a
large enough to permit the test specimen to be cut out with a
vacuum to facilitate removal of entrapped air may facilitate
fresh edge no closer than 13 mm (0.5 in) to an edge of the
re-hydration. Complete hydration should be determined by
original cutting. The sample cutting from which the test
weighingthesampleatappropriateintervalsduringthesoaking
specimen should be taken, should have minimum dimensions
processuntilconstantweightisachieved.Appropriateintervals
of approximately 101 by 101 mm (4 by 4 in.).Acutting taken
between weighings could be 10-15 min for cuttings that have
straight out of the tanning drum prior to wringing need not be
been wrung but not dried out and 30-60 min or more for
pre-soaked and the test specimen can be cut out directly from
cuttings that have dried out significantly. Constant weight is
thissamplecutting.AcuttingtakenfromWetBlueatanypoint
achieved when the difference between successive weighings is
from the wringing operation forward will need to be pre-
less than 60.1 g. After the cutting has been completely
soaked (see 9.1 for details on re-hydration). The standard test
re-hydrated, the test specimen can be cut out from it.
specimen shall be a square 76.0 mm (3.00 in.) on edge. Other
9.2 Before the test specimen is cut out from the completely
size and shape specimens can be used. It is recommended that
hydrated cutting, the beaker of boiling water shall be prepared
for non-standard test specimens the minimum dimension (for a
so it is ready when the test specimen is cut out.A1Lbeaker or
sideofarectangleordiameterofacircle)be51.0mm(2.0in.)
other container shall be filled with sufficient water to gener-
and the maximum dimension (for a side or diameter ) be 102
ously cover the test specimen when fully immersed, but
mm (4.0 in.). Before a test specime
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