ASTM D7476-08

Standard Test Method for Brine Saturation Value of Cured (Salt-Preserved) Hides and Skins

SIGNIFICANCE AND USE
This test method is intended to evaluate whether sufficient salt (NaCl) has been retained by the hides or skins to slow down degradation by bacterial (enzymatic) action, and to slow down autolysis by inherent enzymatic action, until they are preserved by a tanning process.
Note 2—Osmosis occurs during brine curing because moisture is drawn out by salt through the epidermis. Low moisture ( 40 %) in the hides does not necessarily indicate poor cure. A hide may have low moisture due to osmosis; to increased fat content; or to drying out conditions. In all instances the hides would still show adequate cure if the moisture was saturated to approximately 85 % salt, because the ash: moisture ratio would be adequate.
SCOPE
1.1 This test method covers the estimation of degree of saturation of the brine content of cured (salt-preserved) hides and skins containing 40 % or more moisture.
1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.
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.

General Information

• Status: Historical
• Publication Date: 31-Aug-2008
• ICS: 59.140.20 - Raw skins, hides and pelts
• Technical Committee: D31 - Leather
• Drafting Committee: D31.02 - Wet Blue

Relations

• Replaced By: ASTM D7476-08(2013) - Standard Test Method for Brine Saturation Value of Cured (Salt-Preserved) Hides and Skins
• Effective Date: 01-May-2013

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D7476 − 08
StandardTest Method for
Brine Saturation Value of Cured (Salt-Preserved) Hides and
Skins
This standard is issued under the fixed designation D7476; 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 purposes of calculation the ash is assumed to be equivalent to
sodium chloride and the moisture is assumed to be equivalent
1.1 This test method covers the estimation of degree of
towater.Thepercentratioofashtomoistureiscalculated.This
saturation of the brine content of cured (salt-preserved) hides
ratio times 100 is divided by 35.9 (which is the percent salt to
and skins containing 40% or more moisture.
moistureratioinasaturatedsodiumchloride(brine)solutionat
1.2 The values stated in inch-pound units are to be regarded
20°C (68°F)) to estimate the percent of saturation in the brine
as the standard. The values given in parentheses are for
solution in the hides or skins.
information only.
NOTE 1—A saturated solution of sodium chloride at 20°C (68°F)
1.3 This standard does not purport to address all of the
contains 26.4 % by weight of NaCl. Therefore, in 100 g of that saturated
safety concerns, if any, associated with its use. It is the
solution only 73.6 g (100 − 26.4 g) is contributed by water.As such on a
responsibility of the user of this standard to establish appro- weight basis, 100 parts by weight of water will dissolve 35.9 parts [(100
x 26.4)/73.6] by weight of NaCl.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
5. Significance and Use
2. Referenced Documents 5.1 This test method is intended to evaluate whether suffi-
2,3
cientsalt(NaCl)hasbeenretainedbythehidesorskinstoslow
2.1 ASTM Standards:
down degradation by bacterial (enzymatic) action, and to slow
D6715Practice for Sampling and Preparation of Salt Pre-
down autolysis by inherent enzymatic action, until they are
served (Cured) Hides and Skins for Chemical and Physi-
preserved by a tanning process.
cal Tests
NOTE 2—Osmosis occurs during brine curing because moisture is
E177Practice for Use of the Terms Precision and Bias in
drawn out by salt through the epidermis. Low moisture (< 40 %) in the
ASTM Test Methods
hides does not necessarily indicate poor cure. A hide may have low
E691Practice for Conducting an Interlaboratory Study to
moisture due to osmosis; to increased fat content; or to drying out
conditions. In all instances the hides would still show adequate cure if the
Determine the Precision of a Test Method
moisture was saturated to approximately 85 % salt, because the ash:
moisture ratio would be adequate.
3. Terminology
3.1 Definitions:
6. Apparatus
3.1.1 The terms and definitions employed within this test
6.1 Crucible, 30 to 50 mL, high-form, platinum or porce-
method are commonly used in normal laboratory practice and
lain. Prepare crucible by heating it for 15 min in a muffle
require no special comment.
furnace set at 600 6 25°C. Cool in a desiccator before use.
4. Summary of Test Method
6.2 Electric Muffle Furnace, with controller or rheostat and
pyrometer, capable of maintaining a temperature of 650 6
4.1 The moisture (volatile matter by oven drying) and ash
25°C.
contentofacompositehideorskinsamplearedetermined.For
6.3 Desiccator, of appropriate size and charged with fresh
This test method is under the jurisdiction ofASTM Committee D31 on Leather desiccant.
and is the direct responsibility of Subcommittee D31.02 on Wet Blue.
6.4 Analytical Balance, capable of weighing to 0.001 g.
Current edition approved Sept. 1, 2008. Published September 2008. DOI:
10.1520/D7476-08.
6.5 Oven, forced air, capable of maintaining 100 − 105°C.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
7. Reagents and Materials
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
7.1 Distilled or de-ionized water.
“Trade Practices for Proper Packer Cattlehide Delivery,” issued by Leather
Industries of America and U.S. Hide, Skin & Leather Association (printed May
1985). JALCA, 1963, p. 143.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7476 − 08
8. Hazards 10.6 To prevent any loss of ash, very carefully remove the
crucible from the furnace. Warning—The crucible is ex-
8.1 The crucibles will be extremely hot when they are
tremely hot!
removed from the muffle furnace. Therefore, it is suggested
that the analyst handle the hot crucibles using furnace tongs or 10.7 Check the ash condition:
equivalent.
Ash condition Action
White/Gray-white (complete ashing) Proceed to 10.9
9. Sampling
Dark gray or Black (incomplete ashing) Proceed to 10.8
9.1 Sampling shall be per Practice D6715.
10.8 Coolthecrucibletoroomtemperature.Moistentheash
with10–15mLofDIwater,thenplacethecrucibleintheoven
9.2 Timeiscrucialinthepreparationofsalt-preservedhides
until visibly dry. Transfer the crucible to a cool muffle furnace
for chemical testing. Samples should not be prepared if
(≤ 100°C) and repeat steps 10.5 to 10.7.
analysis can not be done immediately. The following proce-
dures should be executed with a minimum of hide exposure to
10.9 Cool the crucible to room temperature in a desiccator.
either air or moisture or salt-absorbent materials (including
10.10 Weigh the crucible immediately and record the
human skin). Ensuring this will prevent or minimize any
weight.
significant or salt loss from the samples.
9.3 Duringallstagesofpreparation,samplesshallalwaysbe 11. Calculation
cut on a non-porous, non-absorbing hard surface using a clean
11.1 Calculate the percentage of moisture (volatile matter
sharp cutting tool, preferably a new razor or scalpel blade.
by oven drying) as follows:
Avoid excess pressure on the sample that could force liquid
D 5 moisture, % 5 A 2 B / A 2 C 3100
@~ ! ~ !#
(moisture) from the hide sample.
where:
9.4 De-hairing, Cleaning, and Dicing:
9.4.1 Without damaging the hide surfaces, carefully remove A = original weight of sample and crucible,
B = weight of dried sample and crucible, and
all the hair and manure from each hide sample using appro-
C = weight of crucible.
priate equipment (clippers, scissors, razor, knife, an so forth),
9.4.2 Remove any loose surface salt or residual undesired
11.2 Calculate the percentage of ash as follows:
material(manure,dirt,andsoforth)fromeachhidesampleand
F 5 Ash, % 5 @~E 2 C!/~A 2 C!# 3100
flesh each sample down to firm corium.
9.4.3 Using appropriate equipment (scalpel, single-edged where:
razor blade, cutting die, an
...