Year: 1888

page_text: Date of Application, 16th Feb.,
1888
Specification Accepted, 29th Mar., 1888
I WILLIAM ZARN, Tanner, of Newark, in the County of Essex and State of New
Jersey United States of America do hereby declare the nature of this invention
and in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
My invention relatos to an improved process of tanning skins for making kid-leather
and the process consists first in preparing the skins for tanning by treating with
sulphate of sodium or arsenic and unhairing the same then treating it with dog-
manure and a solution of salt and water. After this preparatory treatment the skins
are exposed to the action of three different solutions the first solution consisting of
bichromate of potassium salt and muriatic acid; the second solution of hyposulphate
of soda and sulphuric or muriatic acid, and the third solution of a mixture of neat's-
foot oil saponified by caustic soda and extract of quercitron bark or other tannin-
containing extract.
For preparing the skins and producing a strong and soft kid leather in a much
shorter time than heretofore the skins are first treated with sulphate of sodium for
about three or four days; for seven to eight days when arsenic is used. The skins
are then unhaired scraped and placed in dog-manure for some time. The skins are
then cleaned of the dog-manure and placed into a solution of the proportions of five
pounds of common salt and 100 pounds of water in which they are allowed to remain
for about one half an hour. They are then removed and exposed to the first bath
which consists for every hundred pounds of skins of a solution of five pounds of
bichromate of potassium, 2 pounds of salt and 23 pounds of muriatic acid in 5 gallons
of water. The skins are placed with this solution into a tub and rotated by stirrers
in the same for about 30 minutes so as to be thoroughly impregnated by the
solution. The skins are then allowed to remain in the solution for about three hours
after which they are again rotated for about 30 minutes with the saine.
Thinner
skins have to be exposed to the action of the solution for a less length of time
than thicker skins which have to remain for a greater length of time in the solution
so as to be thoroughly impregnated by the same.
The skins are then transferred to the second bath which consists for every hundred
pounds of skins of 8 pounds of hyposulphate of soda and 1 pounds of sulphuric acid
of 66° B., or of 12 pounds of hyposulphate of soda and 3 pounds of muriatic acid

page_text: of 70° B dissolved in ten gallons of water. The skins are placed with either one of
these solutions into a tub and agitated in the same for about half an hour. After an
intermission of half an hour they are again agitated for half an hour and then allowed
to remain in the same from two to ten hours according to the thickness of the skins.
They are then washed and placed into the third bath by which the leather is made soft
and strong and which consists for every 100 pounds of skins of a mixture of
saponified neat's foot oil and a tanning extract. This mixture is prepared of
1 pounds of neat's foot oil and two ounces of caustic soda, which are dissolved in
one gallon of water and heated by steam until the neats foot oil is properly
saponified. Then an extract of 5 pounds of quercitron bark in 5 gallons of water
or any other suitable solution containing tannic acid is added. The skins, are placed
with this solution in the so-called pin-wheel the last solution softening the skins and
imparting the final tanning action to the same. The skins are exposed to the tannic
acid solution for about half an hour after which the leather is removed and dyed in
the usual manner.
For light colors the dye is given to the leather while it is in the pin-wheel, it being
finally washed off and allowed to dry, while for dyeing black it is best to remove the
leather to the working bench and spread the color over the same. A coating of oil is
then given to the leather on the grain-side, after which it is dried at a temperature of
from 70° to 80° F. If a gloss is to be imparted to the leather, a coating of some
vegetable oil, advantageously linseed oil, is finally given which renders the leather
waterproof soft and durable.
By my improved method of tanning skins the same can be changed into leather in
from 14 to 16 days or thereabouts the process producing kid-leather of superior
quality..
: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is-
1st. The method herein described of tanning skins, which consists in subjecting the
skins successively to the action of three different tanning solutions firstly, to a
solution of bichromate of potassium, salt, sulphuric or muriatic acid and water;
secondly, to a solution of hyposulphate of soda, sulphuric or muriatic acid and water,
and thirdly, to a mixture of saponified neats foot oil and a suitable bark extract
substantially as set forth.
2nd. The method herein described of tanning skins which consists first in subjecting
the skins to the preparatory treatment of unhairing softening and cleaning the same
second subjecting the skins to the action of a solution of bichromate of potassium salt
sulphuric or muriatic acid and water thirdly to the action of a solution of hyposulphate
of soda sulphuric acid and water and fourthly to the action of a mixture of saponified
neats foot oil with a suitable bark extract substantially as set forth.
Dated this 16th day of February 1888.