Improvements in the Process of Tanning.
Year: 1899

page_text: Date of Application, 30th June, 1899
Complete Specification Left, 20th Mar., 1900-Accepted, 12th May, 1900
D
PROVISIONAL SPECIFI
Improvements in the Process of Tanning.
1, CARL OTTO NATUSCH, of 4, Seilerstrasse, Hamburg, Germany, Inventor, do
hereby declare the nature of this invention to be as follows:-
Almost all the processes of quick tanning hitherto known, furnish leather of
nferior quality, which is often made very heavy with chemical substances such
as metallic salts or the like. My new process which may be easily and readily
carried into effect without machines or other apparatus, may be advantageously
substituted for the usual tanning process causing great losses of time and much
trouble, and it produces a clear and soft leather of any kind and for any pur-
poses, equivalent to leather produced by oozing, the process may be employed
for producing any kind of thin or thick leather for manufacturing boots and
shoes, belts etc., and for all technical purposes. Thin hides for manufacturing,
for instance uppers of shoes, may be perfectly tanned in 3 to 10 days, and thick
cow-hides in about 21 days.
When vegetable tannine matters, such as catechu dividivi, myrobalans, or the
like are submitted to a continued decoction, a liquor of at least 4° (four) Beaumé
will be obtained, which liquor will be employed at a temperature of 36 42° Cels.
Said liquor at 36-42° is shed into wooden vessels and the prepared hides then
hung or laid therein, the liquor is left for cooling and afterwards heated again
to 420, by leading steam or shedding fresh hot liquor into the vessels.
repeating this twice, a solution of one kilogr. of potassium bichromate is added
to the liquor, and the whole then left, until a perfect tanning is obtained. One
kilogr. of the bichromate is sufficient for eight large cowhides.
After
Thin hides serving to produce leather for fine uppers of shoes or boots, are
dipped without further addition into the liquor already used, the latter is heated
several times and a complete tanning will be obtained in 3 to 10 days.
By the above process, a considerable save of tanning time and work will be
obtained, and a high grade leather produced, which is almost equal to that
produced by oozing processes. The aforegoing process enables me to produce
any kind of light-coloured, soft and flexible leather, as well as hard rigid leather
for any purposes.

page_text: to be performed, to be particularly described and ascertained in and by the
following statement:-
Almost all the processes of quick tanning hitherto known, furnish leather of
interior quality, which is often made very heavy with chemical substances such
as metallic salts or the like. My new process which may be easily and readily
carried into effect without machines or other apparatus, may be advantageously
substituted for the usual tanning process causing great loss of time and mucu
trouble, and it produces a clear and soft leather of any kind and for any purposes,
equivalent to leather produced by slow tanning processes. The process may be
employed for producing any kind of thin or thick leather for manufacturing
boots and shoes, belts etc., and for all technical purposes. Thin hides for manu-
facturing, for instance, uppers of shoes, may be perfectly tanned in 3 to 10 days,
and thick cow-hides in about 21 days.
When vegetable tannin-containing substances, such as catechu, dividivi, mira-
bolanen, or the like, are submitted to a continued decoction, a liquor at least 4°
(four) Beaumé will be obtained, which liquor will be employed at a temperature
of 36-42° Cels. The proportions in which these substances are employed can-
not be determined as they are varied in accordance with the quality thereof but
the resultant liquor must be of a strength of at least 4 (four) Beaumé.
Said liquor at 36-42° Celsius is poured into wooden vessels and the prepared
hides then hung or laid therein; the liquor is allowed to cool (to about 12-18°
Cels.) and afterwards heated again to 42 Cels. by leading steam or pouring fresh
hot liquor into the vessels. After repeating this twice, a solution of one kilogr.
of potassium di-chromate is added to the liquor, and the whole then left, until a
perfect tanning is obtained. One kilogr. of potassium dichromate is added to
about two cubic meters of water which is sufficient for eight large cowhides.
The alternate heating and cooling of the liquor enables one to produce fine
soft and smooth leather, which could not be produced if the liquor were main-
tained at a temperature of 42° Celsius, in which case hard, breakable leather is
obtained.
The hides, serving to produce leather for fine uppers of shoes or boots, are
dipped, without further addition, into the liquor already used for treating thick
hides, said liquor is heated two or three times and a complete tanning will be
obtained in 3 to 10 days.
By the above process a considerable saving of tannin-containing materials,
time and work will be obtained, and a high-grade leather produced, which is
almost equal to that produced by slow tanning processes. The aforegoing process
enables one to produce any kind of light-coloured, soft and flexible leather, as
well as hard rigid leather for any purposes.
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 process of quick tanning which consists in immersing the hides in a
decoction of tannin-containing materials at a temperaure of 360-42° C., of
about the strength specified; cooling the same; restoring the temperature and
again cooling adding a solution of potassium di-chromate to the said liquor and
allowing the hides to remain in the resulting solution till the hides are com-
pletely tanned, substantially as described.
Dated this 20th day of March 1900
DAY, DAVIES & HUNT,
Chartered Patent Agents, 321, High Holborn, London, W.C.,
Agents for the Applicant.