Use of Sulphite Cellulose Extract as a Tanning Material Page: 319
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Wallae] Sulphide Cellulose for Tanning 319
before there was evidence of sufficient contamination to impair the
color of the leather.
(e) TANNING WITH BLENDED LIQUORs.-A series of tanning experi-
ments were conducted using a straight yard tannage with a blend of
13 sulphite celluose extract No. 2, 1 chestnut wood extract, and
1 cutch extract. The hides were prepared as described under the
pretannage experiments and started in a weak liquor containing
1 per cent tannin. They were run through a series of 14 liquors, the
tannin content increasing until the head liquor contained 4 per cent.
All liquors were continually agitated with a mechanical stirrer and
the hides remained 48 hours in each liquor. After removal from the
head liquor the hides were placed in a lay-away vat containing 6 per
cent tannin (700 Bk.) for 7 days. The total time of tannage was 35
days. The usual washing, bleaching, oiling and drying operations
were made in finishing the leather. Ten lots of hides were run
through these liquors and in each case the liquor, when discarded, con-
tained less than % per cent tannin, showing that the sulphite cellu-
lose extract had been adsorbed by the hide along with the other
materials used. The average yield of the 10 lots was 72 per cent and
the degree of tannage averaged 68, varying from 66 to 71 for the
different lots.
Companion tests were run using oak bark extract alone, and the
time required to secure leather of the same degree of tannage and
yield was 40 days.
In all tanning tests the time required was that found necessary by
experiment to produce leather of approximately 70 degree of tannage.
These tests indicate that sulphite cellulose extracts may be blended
with the usual vegetable extracts and satisfactorily used in the tan-
ning stages. The economy of its use depends upon the comparative
price per unit of tannin content and the efficiency with which the
various materials may be utilized.
A factor to be considered in the use of sulphite cellulose extracts is
that they are more acid in character than the ordinary vegetable
extracts. These extracts can be so blended with the latter as to
produce liquors of nearly the desired acidity. Thus the substitution
of the more costly tanning materials by sulphite cellulose extracts
leads also to the possible exclusion of those higher priced materials
on which the tanner depends to produce acidity through fermentation.
By blending in such proportions as to give an acid concentration
slightly below that desired, the acidity can readily be adjusted by
the use of lactic acid and an essentially sterile series of liquors secured
in which the acidity can be more easily, accurately, and scientifi-
cally controlled.
(f) EVALUATION OF TANNED LEATHER.-In Table 5 will be found
the chemical analyses for the various lots of leather tanned.
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Wallace, E. L. & Bowker, Roy Clement. Use of Sulphite Cellulose Extract as a Tanning Material, report, November 1, 1926; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc66515/m1/13/: accessed March 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.