WEARING QUALITIES OF SHOE LEATHERS. 
23 
vestigation. Disregarding the possibility of misfitting, it would seem 
that a full double sole and double shank of heavy leather are responsi- 
ble for the wasteful excessive toe wear. A shoe with such a sole bends 
but little and the weight of the body is concentrated at the extreme 
end of the sole, instead of being distributed over a greater area at the 
ball. Even when a double sole is used on the ball of the foot, the 
shank should not be doubled, thus saving leather in making the shoe, 
lengthening its period of service, and reducing the cost of repair. 
Serviceability of various tannages. — The average wear resistance of 
the vegetable-tanned sole leathers, classified according to the predom- 
inating tanning material, is practically the same for all three types, 
being per 9 irons as follows: Oak bark tannages, 78 days; hemlock 
bark tannages, 79 days; and chestnut wood extract tannages, 80 
days. Belting leather shows a slightly higher wear resistance, 
the average wear per 9 irons being 85.5 days. Waxed ciircme- 
tanned leather, with 102 days wear, was next in order, while un- 
waxed chrome-tanned leather, with an average of 126 days wear, was 
best of all. Fiber soles, with an average of 122 days wear, were a good 
second, except for the physical failures already discussed. The results 
are charted in Figure 2. 
J 
OAK -.--- 
c//Esr/wr 
OAX BEIT/ A/3 
WAXE0 C///?OAfE- 
F/SEX - — 
UV WAXED CHfiOfifft 
O 
I 1 
/O 20 JO 40 50 60 TO 30 SO /OO //O /20 /30 
Al/EXAGE DArS WEAR FEZ? 9 //?0/VS 
Fig. 2.— Summary of wear data on soles. 
The longer wear of the chrome-tanned leathers, both unwaxed and 
waxed, and of the fiber soles warrants further consideration of these 
materials. The results indicate that unwaxed chrome-tanned leather 
may be exceptionally serviceable in dry sections of the country. The 
influence of the climate in this connection must be emphasized. 
Unwaxed chrome-tanned leather is not suited for wear in damp or 
wet places, because it is very porous and consequently readily takes 
up water. This is the primary reason for the manufacture of waxed 
chrome-tanned leather, which is simply chrome-tanned leather im- 
pregnated with large quantities of waxes and other materials to make 
the leather more water resistant. 
Loaded leathers. — Under the conditions of these tests, loading with 
glucose and epsom salts does not materially affect the serviceability 
of leather. It simply adds to the cost. These findings, however, 
might have been quite different had the shoes been worn where the 
climate was wet. 
Rolled leathers. — Approximately 16 per cent greater wear for the 
rolled than for the unrolled leathers was shown. 
