|
Property
|
Ideal
material
|
Leather
|
| Strength |
Tear
and tensile strength should be high to withstand lasting |
Good.
Usually much higher than is needed unless oversplit or poorly tanned |
| Stretch
at break |
Should
be enough to last any style of footwear and allow further stretch
in wear. Minimum of 15 percent |
Good.
Tanner has some degree of control |
| Modulus
(ease of stretch) Flexibility |
Should
not be too low or lasting may be uneven. Any variation should be
predictable (ie lines of tightness) |
Lies
in the right range. The direction of tightness varies but is predictable.
Tanner has some control over the degree of tightness. |
| Plasticity |
Normally
should be low to resist shape loss in wear, but should be possible
to make it during lasting, then low again afterwards |
Very
good. Plasticity is increased by moisture and lowered again on drying
out. Easy to flkatten wrinkles on lasted margin. can be shaped at
room temperature given time |
| Cutting |
Should
cut cleanly in the clicking, skiving and splitting operations. Should
not blunt knives. |
Very
good. Can be split very thinly. |
| Stitch/Tack
holding |
Should
resist tearing through and keep components firmly together. |
Very
good. Upto 26 SPi are possible without undue weakening of seams |
| Dimensional
stability |
Should
not expand or shrink in are due to changes in temperature or humidity |
Expand
slightly in moist conditions. Some tannages may shrink badly in
hot moist conditions |
