Year: 1898

page_text: I, GUSTAV FEITHI, of Skalitz, Bohemia, in the Empire of Austria, Manu-
facturer of Leather, do hereby declare the nature of this invention to be as
follows:-
This invention relates to a rapid process of tanning by which even the heaviest
hides may from their raw condition be perfectly and completely tanned within
4 to 5 weeks.
This process is distinguished from the methods of rapid tanning hitherto
known by the following principle: viz., The materials used for tanning are
not directly applied to the hides in their commercial form and quality as obtained
in the market but are first converted into a substance containing a certain
percentage of acid.
It cannot be said of the rapid tanning processes hitherto proposed that they
have proved very satisfactory, when put to a practical test, as there have always
been certain inconveniences attendant upon them. Taking for instance the pro-
cesses by which the hides immediately after cleaning with lime are subjected to
fulling and highly concentrated solutions of extracts used from the very begin-
ning the whole process of tanning lasting from 36 to 48 hours no product of
good quality and suppleness could be obtained. The leather thus prepared was
brittle and light and had a bad and partly contracted grain.
On the other hand by the processes, in which steam or turpentine oils salts or
alkalies are used there is also obtained a more or less imperfect kind of leather
with the further disadvantage of a bad colour.
It is a generally admitted fact, that up to now the old method of tanning
gives the best leather both as regards its quality and saleability. This is
chiefly due to the use of acidulated liquids in place of sweet lyes of tannin the
leather being acted upon first by weak lyes of tannin of gradually increasing
strength. The small percentage of acid in the liquid not only does not injure
the leather but on the contrary it materially improves its strength quality and
weight.
The present process of tanning while following the principle of the action of
acidulated tanning substances of gradually increasing strength as employed
in the old method accelerates the time of treatment to such a degree that within
the time stated above the hides are perfectly tanned.
This saving of time is due to the following circumstances:
(1) With the old method the formation of acidulated fluids (mordants) pro-
ceeds very slowly by the action of the air and by filling the pits and vats with
acidulated liquids or water kept in a reservoir for the purpose whereas according
to the present process the tanning substances or extracts to be applied are im-
mediately before use rendered acid to the extent of from 1 to 2, 4 8 or more
per cent. of acid by the addition of acid such as for instance oxalic tartaric.
salicylic or crude carbolic acid.

page_text: (2) The hides while in a rotating vessel are treated during the whole duration of
the tanning process with acidulated lyes of tannin of gradually increasing strength
and alternately with compressed and ordinary air. This process is carried out
as follows:-
―:
The hide after having passed the usual lime treatment is, put into an artifi-
On the
cially acidulated mordant of 2 to 4% according to Eitner's aerometer.
second day the hide is transferred to a mordant of 4% higher strength
and this is continued during 6 or 8 days with the result that on the 8th day
the mordant has a strength of 20 or 22% or even more.
If in this way the hide has been properly prepared it is put into a revolving
cask or vessel containing a stronger acidulated lye or mordant than that used
during the stage of treatment before described. During the 1st to the 3rd hour
of treatment the liquid in the cask is subjected to the action of compressed air.
During the interval between the 3rd and 6th hour rarified air is applied in place
of the compressed air an air tap in the axle of the cask having been opened for
that purpose. Subsequently the tannin liquid in the cask is made stronger by
the addition of acidulated extracts of tannin substances and the hide is for
2 hours subjected to the combined action of the liquid motion and compressed
air. Then the tap in the axle of the cask is again opened, the strength of the
liquid is again increased and this, alternately with the application of compressed
air and the further gradual increase of the strength of the liquid, is continued
From the 12th to the 13th,
From the 18th to the 19th and
From the 25th to the 26th hour.
After this period the hide is transferred into a second cask or vessel containing
a somewhat more acidulated liquid than the first cask and the former treatment
with the action of alternately compressed and ordinary air and the gradual addition
of extracts of increasing acidity is repeated until the tanning is completed.
The hide is then subjected to disacidification after which it has to be finished
Dated this 4th day of July 1898.
BOULT & WADE,
Agents for the Applicant.
I, GUSTAV FEITI, of Skalitz, Bohemia, in the Empire of Austria, Manu-
facturer of Leather, 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:--
This invention relates to a rapid process of tanning, by which even the heaviest
hides may from their raw condition be perfectly and completely tanned within 4
to 5 weeks.
This process is distinguished from the methods of rapid tanning hitherto
known by the following principle viz.: The materials used for tanning are
not directly applied to the hides in their commercial form and quality as obtained
in the market, but are first converted into a substance containing a certain
percentage of acid.
It cannot be said of the rapid tanning processes hitherto proposed that they
have proved very satisfactory, when put to a practical test, as there have always
been certain inconveniences attendant upon them. Taking for instance the pro-
cesses, by which the hides immediately after cleaning with lime are subjected to
fulling, and highly concentrated solutions of extracts used from the very begin-

page_text: ning, the whole process of tanning lasting from 36 to 48 hours, no product of
good quality and suppleness could be obtained. The leather thus prepared was
brittle and light and had a bad and partly contracted grain.
On the other hand by the processes, in which steam or turpentine, oils, salts or
alkalies are used, there is also obtained a more or less imperfect kind of leather
with the further disadvantage of a bad colour.
It is a generally admitted fact, that up to now, the old method of tanning
gives the best leather both as regards its quality, and saleability. This is
chiefly due to the use of acidulated liquids in place of sweet lyes of tannin, the
leather being acted upon first by weak lyes of tannin of gradually increasing
strength. The small percentage of acid in the liquid not only does not injure
the leather, but on the contrary it materially improves its strength, quality and
weight.
The present process of tanning while following the principle of the action of
acidulated tanning substances of gradually increasing strength, as employed
in the old method, accelerates the time of treatment to such a degree, that within
the time stated above, the hides are perfectly tanned.
This saving of time is due to the following circumstances: —
(1) With the old method the formation of acidulated fluids (mordants) pro-
ceeds very slowly by the action of the air, and by filling the pits and vats with
acidulated liquids or water kept in a reservoir for the purpose, whereas according
to the present process the tanning substances or extracts to be applied are im-
mediately before use rendered acid to the extent of from 1 to 2, 4, 8 or more
per cent. of acid, by the addition of acid, such as for instance, oxalic, tartaric,
salicylic or crude carbolic acid.
(2) The hides while in a rotating vessel are treated during the whole period of
the tanning process with acidulated lyes of tannin of gradually increasing strength
and alternately with compressed and rarified air. This process is carried out
. as follows:
-
The hide after having passed the usual lime treatment is put into an artifi-
cially acidulated mordant of 2 to 4% according to Eitner's aerometer. On the
second day the hide is transferred to a mordant of about 4% higher strength
and this is continued during 6 or 8 days with the result that on the 8th day
the mordant has a strength of 20 or 22%, or even more.
If in this way the hide has been properly prepared, it is put into a revolving
cask or vessel containing a stronger acidulated lye or mordant than
that used during the stage of the treatment before described. During the first
three hours of treatment the liquid in the vessel is subjected to the action of
compresssed air. During the second three hours rarified air is applied in place
of the compressed air, an air tap in the axle of the cask having been opened for
that purpose. Subsequently the tannin liquid in the vessel is made stronger by
the addition of acidulated extracts of tanning substances and the hide is for
2 hours subject to the combined action of the liquid, motion and compressed
air. Then the tap in the axle of the cask is again opened, the strength of the
liquid is again increased and this, alternately with the application of compressed
air and the further gradual increase of the strength of the liquid, is continued
From the 12th to the 13th,
""
"
18th
25th
"
"
"
"
وو
19th, and
26th hour.
After this period the hide is transferred to a second cask or vessel containing
a somewhat more acidulated liquid than the first vessel and the former treatment
with the action of alternately compressed and rarified air and the gradual addition
of extracts of increasing acidity is repeated until the tanning is completed.
I prefer that the vessels should not be rotated always in the same direction,
but first in one and then in the reverse direction, say for periods of from 2 to 5
minutes each way.

page_text: The hide is finally subjected to de-acidification after which it has to be finished.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed, I declare that what
I claim is;
1. A rapid tanning process characterised by a preparatory treatment of the
hides, after liming, with artificially acidified tanning lyes of gradually increas-
ing strength and subsequently treating the hides in a rotatory vessel under the
combined action of acidified tanning extracts or solutions of suitable strength
and of alternately compressed and rarified air, substantially as described.
2. In a process of the kind described the use of tanning extracts or solutions
acidified by the addition of acid such as tartaric, salicylic, oxalic or crude carbolic
acid substantially as described.
3. The complete process of tanning leather substantially as described.
Dated this 20th day of March 1800
BOULT & WADE,
Agents for the Applicant.