Quote:
Originally Posted by
T4phage 
but so far
none of my shoes
have 'deformed' for lack
of this side lining
(oldest one about 10 yrs)
Whether side linings are essential, I wouldn’t know, but they are considered good practice in North-European shoemaking. (The Dutch name might be similar to the German name
“Überstemme”).
No idea, if Latin shoemakers use them routinely, occasionally or not at all.
Quote:
The object of using the side lining is to continue the support around the feather line of the shoe between the ends of the heel-stiffener and the toe-box.
The waist, under the joints, and the forepart have to stand the whole strain of the bending and flexing of the foot. These parts of the shoe cannot be made rigid as in the heel portion and the toe, because it would interfere with the flexibility of the shoe in walking, but some additional support around the feather line of the shoe is required to stand the strain and stress placed upon it at these points. Hence the necessity of a light but good side lining.
W Wardley in F Y Golding (editor) “Boots and Shoes” Volume IV (London 1935)
Quote:
Originally Posted by
T4phage 
is that your sharkskin chukka rolf?
Nope, no fish. Those boots are shrunken Kudu.

Quote:
Originally Posted by
T4phage 
bestetti doesn't use it
but he does refer to
'leather reinforcement'
for some more delicate leathers.
That refers to a “backer” where the underside of piece of leather gets laminated (glued-on over its entire area) with another piece which can be either leather or synthetic, to give it more “body” (same principle as glued-on interfacings in tailoring).