AN IMPROVED PROCESS FOR THE MANUFACTURE OF GLAZED LEATHER
Year: 1885

page_text: I, THOMAS RUSSELL CLARK, of the firm of Fisk, Clark and Flagg, Manufacturers
of Leather, of the City of New York, in the County and State of New York, and
United States of America, do hereby declare the nature of my invention for AN
IMPROVED PROCESS FOR THE MANUFACTURE OF GLAZED LEATHER, and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
This invention relates to that class of leather which is commercially known as
"French glazed kid" and which is chiefly employed in the manufacture of ladies'
fine shoes.
In the manufacture of this class of leather the presence of any trace of oil or
grease in the skin is fatal to the production thereon of the fine glazed surface
constituting its distinguishing characteristics and for which it is so highly prized.
Consequently, glazed kid leather has heretofore been manufactured chiefly of skins
tawed with lime, alum, and salt, and occasionally of skins tanned with bark by
processes involving the use of lime, the use of skins tawed with oil being wholly
discarded.
It is however well known that the fibre of the skins is measurably weakened by
the use of lime in tawing the same and that the "glazed kid" heretofore produced
from alum-tanned leather is lacking to. a certain extent in toughness and also
cracks upon its glazed surface to a greater or less degree.
The object of this invention is to obtain a glazed kid leather which shall
combine with a perfectly glazed surface of the highest finish, all the suppleness,
strength, and toughness of the best oil-tawed leather and which shall consequently
be free from the objectionable tendency to crack under strain which, as stated, is
inherent in the glazed, alum-tanned, shoe leather heretofore manufactured.
As the result of long continued series of experiments, this object has been
attained by first subjecting skins which have been thoroughly tanned or tawed by
any of the customary processes in which the skin is toughened and cured by means
of oil or grease or compounds of oil or of grease, to the detergent action of naptha
or any of its known equivalents, the skin being completely drenched in successive
baths of pure naptha repeated until every trace of oil or grease or solvent animal
matter is removed; and thereafter coloring and polishing one side of the cleansed
skin in manner as is well known to the art to produce a fine black glazed or
polished surface.
It is unnecessary to describe the method of tanning or tawing the skins with
oil to toughen and cure them which constitutes the first step in my process. Any
of the processes of oil-tawing which are well known to the art may be employed,
a selection being made for this purpose of such of the known processes as bave
been found to produce the toughest and most durable as well as soft and supple

page_text: leather from the particular character of skins in hand. After the skin has been
tawed with oil and finished to the white and brought to a soft and pliable
condition it is thoroughly dried to remove therefrom so far as practicable every
trace of moisture, and the dry. skins are then immersed in a bath of pure refined
naptha, preferably the ordinary commercial naptha of about 70° Baumé, or other
equivalent volatile hydro-carbon oil,-in a tank or close vessel which is either
made to revolve, or in which the skins are otherwise agitated by means of
rotating-arms or stirring devices so as to ensure a rapid and thorough permeation
thereof by the fluid. This agitation is continued until the naptha becomes so
fully saturated with the greasy and oily matter extracted thereby from the skins
as that it will take up no more.
The skins are then removed to a second clean
bath of pure naptha and drenched therein as in the first case, and this operation
of subjecting the skins to a fresh supply of naptha in a clean vessel, is repeated
again and again until the naptha in which the skins are last placed will remain
pure, and so far unaffected thereby as not to show upon proper test the least trace
of oil or grease.
Where the skins, in the original step of tanning or tawing, were treated with
impure oil, it may become necessary to further purify them from the traces of
gummy or resinous matters which have resisted the solvent action of the pure
naptha and for this purpose they may be subjected to a drenching with alcohol,
wood-spirits, ammonia or other equivalent solvent for gummy and resinous
substances.
The skins are then hung up, and dried and staked out preparatory to being
colored, and are finally dyed and polished by the use of polishing machines in
manner as is well known to the art for the purpose of producing thereon the
desired glazed surface.
The simplicity of this process renders it comparatively inexpensive and it
produces the finest quality of glazed leather having all the toughness and desirable
qualities which are inherent in oil-tawed skins with a peculiar toughness in the
glazed surface which is wholly novel and has heretofore been deemed to be
unattainable.
I do not claim as new the use of the naptha in extracting oil from leather, for
the purpose of cleansing the skin and of recovering the oil, the use of naptha in
this invention being merely one of a series of steps, as above specified, in a novel
process for converting skins which have been tawed with oil or oily compounds
without the use of lime or other chemicals injurious to the fibre of the skin, into
an exceedingly tough and supple glazed leather such as has not heretofore been
produced,
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what
I claim is
The improvement in the art of manufacturing glazed leather which consists,
substantially as herein described, in first, tawing skins with oil or oleaginous
compounds; second, drying them; third, subjecting them to repeated drenchings in
successive baths of clear naptha, until fully cleansed and whitened; fourth, drying
and staking them; and finally dyeing and glazing them in the customary manner.
Doted this 20th dow of June 1885