WEARING QUALITIES OF SHOE LEATHERS. 
11 
) 
Effect of Oiling Leather. 
As a rule, American sole leathers contain but little oil or grease. 
One of the problems on which it was planned to throw some light in 
this investigation was the effect on the wearing quality of leather of 
materially increasing its oil or grease content. 
Table 5 shows the effect on wear of increasing slightly the oil 
content in certain leathers. 
Table 5. — Effect of oiling on wear of sole leather. 
Lot 
No. 
Description of leathers. 
Oak tannage: 
Regular 
Same as lot 10 ex- 
cept not bleached 
or drummed and 
containing more 
oil 
Chestnut tannage: 
Regular 
Same as lot 13 ex- 
cept containing 
less glucose and 
more oil 
Regular 
Same as lot 24 ex- 
cept low in glu- 
cose and epsom 
salts and high in 
oil 
No. of 
soles, 
20 
20 
Composition of original leather (moisture-free basis). 
Total 
ash 
Per 
cent. 
1.83 
,72 
.76 
2.50 
Petro- 
leum- 
ether 
ex- 
tract. 
Per 
cent. 
2.76 
4.79 
1.78 
4.58 
1.79 
7.48 
TJn- 
com- 
bined 
tan- 
nin. 
Pa- 
cent. 
13.71 
14.40 
li.39 
13.28 
16.56 
Non- 
tan- 
nins. 
Per 
cent. 
14.17 
10.10 
12.52 
8.60 
11.94 
6.50 
Water 
solu- 
bles. 
Per 
cent. 
27.88 
24.50 
23.91 
21.88 
28.50 
21.04 
Ep- 
som 
salts. 
Per 
cent. 
2.90 
1.25 
1.49 
1.75 
1.73 
Glu- 
cose. 
Per 
cent. 
4.40 
1.66 
5.53 
2.47 
4.11 
.33 
Hide 
sub- 
stance 
Per 
cent. 
38.21 
39.30 
45.00 
45.34 
44.56 
45.56 
Com- 
bined 
tan- 
nin. 
Pa- 
cent. 
30.70 
31.15 
29.15 
28.08 
24.89 
25.67 
Aver- 
age 
days 
wear 
per 9 
irons. 
87 
S4 
1 Contained also 1.73 per cent of barium chlorid. 
The results in Table 5 show very little difference in wear between 
a sole leather having the usual oil content and one having a somewhat 
higher oil content. Eight per cent greater wear is shown for the 
leather having the usual oil content. This might be decidedly differ- 
ent if the shoes had been worn in a wet climate. The difference 
between the oil contents of the two classes of leather is not great 
enough to warrant a definite conclusion. 
Effect of Acid Tannage. 
In so-called acid tannages the hides are plumped with sulphuric 
acid before being tanned or in the rockers, rather than with the 
natural organic acids of the tanning materials, as is the case with 
nonacid tannages. Comparatively little acid sole leather is now 
being made. 
Table 6 shows the effect of acid tannage on the wear of chestnut- 
tanned leathers. 
