Arrangement for Performing a Continuous Mode of Tanning.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Arrangement for Performing a Continuous Mode of Tanning.
We, HERMANN SCHMIDT, Manufacturer of 64, Herderstrasse Uhlenhorst
near Hamburg and JULES LANDINI, Merchant of 64 Herderstrasse, Uhlenhorst
near Hamburg in the Empire of Germany, do hereby declare the nature of this
invention to be as follows:-
It is an unshaken fact that a good tanning can only be performed by bringing
to the skins from which the hair has been taken off, only tannin solutions of very
little concentration penetrating at the same time into the inner part of the skins
and covering each single fibre with an infinite thin layer of tannin and by
reinforcing by degrees these solutions, performing thus further deposits of tannin.
By these thin layers of tannin, which are conducted to the fibres by thin solutions,
the capacity of absorption of the skin is not abrogated and therefore, there is no
difficulty for any further liquids of entering the skin, whilst on the other side if
the uncovered skin is directly exposed to a strong solution, the ends of the fibres
lying on the surface are directly covered with a close compact layer of tannin by
which the intervals of the fibres are so filled up that the greatest difficulties are
prepared for any further quantities of tannin entering the skin.
Therefore the first principle of tanning must be to begin with very
little material and to continue with larger quantities from operation to
operation.
8.
It is by the difficulties which are opposing in the tanneries to this principle that
the productions won by tanning with oozes (by quick tanning) are much
inferior in strength and tenacity to the leather which is tanued after the old
method.
Formerly the skins were suspended in waving reservoirs, which were filled with
very weak oozes; the skins lay in these oozes or acids several hours and then they
were brought into acids getting stronger and stronger. The circumstantiality
caused by changing the skin from one reservoir to another, had the consequence
that whole weeks were wanted for the perfect tanning of skins whilst by the
unclean substances and decompositions caused in this time in the tannin, quite
annulled the density and compactness of the latter. There was soon no means to
determine the quantity of the tannin being in an acid already employed as some-
times by the solid substances of the skins communicated to the ooze, that
ooze, which seemed the most close or compact contained the least real
annin.
The consequence of this circumstance was that often in the beginning too
compact solutions were brought to the uncovered skins so that afterwards the
Following solutions which were more compact but possessed less tannin, had no
nore effect.
No less unfavorable was the tanning by letting the skins in reservoirs and by
passing the ooze or acid through them. Also in this case a pretty long time for
perfect tanning is wanted and the parts of flesh dissolving in the acid render it

page_text: impossible to judge the tannin as to its compactness and annul thus every control
of the management. The same may be said of the tanning in barrels.
This method consists in filling a barrel or batt with a solution of six degrees and
skins. This barrel is then put into rotation. Directly the skin sucks up one
part of the tannin, until the stuff sucked by the skin possesses the same compactness
as the surrounding solution and the tanning is naturally ended with the infusion.
The tanner, standing before the rotatory barrel can't observe the entrance of the
tannin into the inner part of the skin; after his opinion he pumps a reinforced
ooze into the barrel and tries to concentrate this acid to 6 degrees, but he has no
security at all for his work, as the different structure and treatment of the
skin in the preparing works is of influence for its tanning.
The work being performed, the just employed acid is thickened to 6 degrees.
and employed again. But as the unclean substances meddled with the acid have
nothing to do with the arcometer compactness of the tannin, the already used acid
of six degrees is quite different from the fresh one of 6 degrees. These & other
difficulties opposing till now to the known proceedings of quick tanning and
preventing the proceeding to be performed in that manner, which might be
regarded and declared right, have caused the inventors to create an arrangement
permitting a continuous method of tanning.
Before our describing the advantages of this method, represented in the
annexed drawings in the Figures 1 & 2, its arrangement and effect will be
explained as follows.
The mentioned arrangement consists of a series of for instance four cylindrical
drums A, B, C, D turning around their axis. In these drums, in the manner
bereafter described the skins lying in them are brought in connection with oozes
being at first weak and getting stronger & stronger in such a manner that if the
ooze has delivered in the one drum to the skins part of its tannin, and is conse-
quently sunk in its concentration, it is brought in the next following drum to
skins, which have already been connected with weaker oozes. In this drum it
again delivers a part of its tannin and if in this manner again sunk in its
concentration it gets into the next drum, until at last, being of a very poor con-
centration the ooze is conveyed into that drum, which has just been filled with
fresh skins,
For this purpose the drums A, B, C, D are provided with a particular
extract-conduit, a waste-water-conduit, an extract-pressure-conduit and air-
pressure-conduit, so that each drum can be provided with new skins without the
proceeding of any other being interrupted.
It may be supposed that the drums A, B, C are working, but that the drum D
has been put out of motion for taking out the tanned skins and for providing it
with new ones. Drum A may contain a solution of strong concentration, drum B
of a middle one and drum C one of a low concentration..
The skins in drum A having suffered a thorough tanning, the valve F of the
air-pressure-conduit D 1 is opened, so that by opening in the same moment the
valves and Q: compressed air is brought in to the drums A and C. In
consequence of the overpressure thereby produced in these drums, the solution or
ooze of the drum C being of weak concentration and having acted on fresh skins,
to which it has nearly communicated all its tannin, is pressed by the waste-
pipe by the pipes ; and valves S, Y into the extract-conduit L, which
conveys the ooze to further purposes, whilst the acid, being in the drum A and
now sunk to middle concentration in consequence of its delivery of tannin to the
now tanned skins, gets, after closing the valve Q through the wastepipe the
pipes fgvalves $1 T 1, pipe h, heater F 2, valve R2, tube d² and
supply-pipe a into the drum B and presses out from this one the solution which
formerly possessed middle concentration but has now sunk to low concentration
for its baving communicated the tannin to the skins, into the drum C. Then, the
valve F being closed, new ooze or acid of strong concentration is conducted from
the reservoir M through the pipes E, &, the valve Q₂ pipe d and the supply-

page_text: pipe a into the drum B, the skins contained therein were before in communication
with a middle ooze. The latter is brought by the waste-pipe b², the tubes f2 g²
valves ST2 pipe h³, heater F 3, valve R³, tube d³ and supply-pipe a³ to the drum C,
whilst the weak concentrated ooze is pressed from C to the drum D. The latter
has meanwhile heen provided with fresh skins and has been put into activity.
As soon as the oozes in the drums B, C, D have acted long enough upon the
skins lying in these drums so that these skins have been thoroughly tanned, the
valve F of the compressed-air-conduit and the valves Q, and Q, are opened, and
the ooze, being in the drum D, which has nearly totally delivered its tannin is
pressed by the compressed air through the waste-pipe 6 pipes f, g, valves 'S Y
into the extract-conduit L, by which it is led off in order to serve for further
proceedings. The ooze being in drum B, which has sunk to middle concentration,
is pressed at the same time to the drum C after the valve Q, being closed and the
acid from C now of a low concentration is pressed to D..
Drum A after having been discharged of its well tanned skins and provided
with new ones, now is put into activity, and a stronger concentrated ooze is
conducted from the reservoir M (the valve F being closed) through the pipes E. c
valve, Q pipe, d and the supply-pipe a into the drum C, so that the middle
concentrated ooze is pressed from C to D, whilst the ooze of a weak concentration:
being in D gets through the waste-pipe 6, pipes f, g, valves S, T into the
conduit U, through this one into the heater F and from here through pipe e',
valve R', pipe d and the supply-pipe a' into the drum A, in order to act therein
upon fresh skins. Drum B is meanwhile put out of activity in order to take out
thereof the tanned skins and to provide drum B with new skins.
In the described manner the drums are put out of activity the one after the
other, and the drums being in activity are always at first provided with acids of
weak, then of middle and then of stronger concentration, so that the skins being
in the drums are connected with solutions of tannin getting gradually stronger.
Before each drum there is a heater F¹ to F which the acid must pass before
its entrance into the drum in order to be more or less warmed as circumstances
may require.
The warming itself is effected by means of the winding-pipes S, to S, which can
be provided with heating steam by a steam-pipe-conduit.
The water-pipe-conduit W is in connection by valves X, to X, and tubes A to
with the single heaters and has the purpose if necessary to bring water to the
solution of the tannin, and to diminish the concentration of the ooze.
The drums A, B, C, D are provided with perforated edges a to z Figs. 1 and 2.
In the annular space between the edge and the drum-wall Fig. 2 there are the
supply-pipes a' to a' and the waste-pipes 6' to '.
The perforated edge has the purpose to distribute the solution of tannic acid
entered through the supply-pipe quite equally to the contents of the drum and to
retain little parts of flesh and uncleaning substances from the acid, before its being
pressed into the next drum; the tanning being finished these uncleaning substances
may be removed.
Each of the drums A, B, C, D is arranged upon trestles H, T, H' T', H' T³,
HY and strongly connected with a toothed wheel K' K2, K³, K so that, if one
of the latter is put into rotation by means of the transmission, the drum, being
attached to it, which is in activity rotates, by which proceeding an easier and more
equal communication of the skins with the tannin is effected.
The tannic-acid or ooze to be used is warmed in a coop N, from which it gets
into the reservoir M, which, as described before, can be connected with the
different drums.
By means of the described arrangement it is possible to regulate mathematically
exactly and continuously the quantity of the tannin to be added to the ooze.
The oozes are used nearly to the last rest. The necessary working expenses
become considerably smaller; & also such a quick & tender tanning is performed
as it was impossible till now by all known methods. Skins wanting 40-70 hours

page_text: for being tanned in barrels, are tanned by the described method much better in
5-6 hours.
Dated this 18th day of June 1896
Arrangement for Performing a Continuous Mode of Tanning.
We, HERMANN SCHMIDT Manufacturer of 64 Herderstrasse, Uhlenhorst near
Hamburg, and JULES LANDINI Merchant of 64 Herderstrasse, Uhlenhorst near
Hamburg in the Empire of Germany 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 :-
It is an unshaken fact that a good tanning can only be performed by bringing
to the skins from which the hair has been taken off, only tannin-solutions of very
little concentration penetrating at the same time, into the inner part of the skins
and covering each single fibre with an infinite thin layer of tannin and by
reinforcing by degrees these solutions performing thus further deposits of tannin
which are conducted to the fibres by thin solutions, the capacity of absorption
of the skin is not abrogated and therefore, there is no difficulty for any further
liquids of entering the skin, whilst on the other side if the uncovered skin is
directly exposed to a strong solution, the ends of the fibres lying on the surface
are directly covered with a close compact layer of tannin by which the intervals
of the fibres are so filled up that the greatest difficulties are prepared for any
further quantities of tannin entering the skin.
Therefore the first principle of tanning must be to begin with very little
material and to continue with larger quantities from operation to operation.
It is by the difficulties which are opposing in the tanneries to this principle that
the productions won by tanning with oozes (by quick tanning) are much inferior
in strength and tenacity to the leather which is tauned after the old method.
Formerly the skins were suspended in waving reservoirs, which were filled with
very weak oozes; the skins lay in these oozes or acids several hours and then they
were brought into acids getting stronger and stronger.
The circumstantiality caused by changing the skin from one reservoir to another,
had the consequence that whole weeks were wanted for the perfect tanning of skins
whilst by the unclean substances and decompositions caused in this time in the
tannin, quite annulled the density and compactness of the latter.
There was soon no means to determine the quantity of the tannin being in an
acid already employed as sometimes by the solid substances of the skins communi-
cated to the ooze, which seemed the most close or compact contained the least
'real tannin.
The consequence of this circumstance was that often in the beginning too
compact solutions were brought to the uncovered skins so that afterwards the
following solutions which were more compact but possessed less tannin, had no
more effect.
No less unfavorable was the tanning by letting the skins in reservoirs and by
passing the ooze or acid through them. Also in this case a pretty long time for
perfect tanning is wanted and the parts of flesh dissolving in the acid render it
impossible to judge the tannin as to its compactness and annul thus every control
of the management. The same may be said of the tanning in barrels.

page_text: This method consists in filling a barrel or butt with a solution of six degrees and
skins. This barrel is then put into rotation. Directly the skin sucks up one
part of the tannin, until the stuff sucked by the skin possesses the same com-
pactness as the surrounding solution and the tanning is naturally ended with
the infusion.
The tanner, standing before the rotatory barrel can't observe the entrance of the
tannin into the inner part of the skin; after his opinion he pumps a reinforced ooze
into the barrel and tries to concentrate this acid to 6 degrees, but he has no security
at all for his work as the different structure and treatment of the skin in the
preparing works is of influence for its tanning.
The work being performed, the just employed acid is thickened to be 6 degrees
and employed again.
But as the unclean substances meddled with the acid have nothing to do with the
arcometer compactness of the tannin, the already used acid of 6 degrees is quite
different from the fresh one of 6 degrees.
These and other difficulties opposing till now to the known proceedings of quick
tanning and preventing the proceeding to be performed in that manner, which
might be regarded and declared right, have caused the inventors to create an
arrangement permitting a continuous method of tanning.
Before our describing the advantages of this method, represented in the drawings
filed with the Provisional Specification in the Figures 1 and 2, its arrangement and
effect will be explained as follows.
The mentioned arrangement consists of a series of for instance four cylindrical
drums A, B, C, D, turning around their axis.
In these drums in the manner here after described the skins lying in them are
brought in connection with oozes being at first weak and getting stronger and
stronger in such a manner that it the ooze has delivered in the one drum to the
skins part of its tannin and is consequently sunk in its concentration it is brought in
the next following drum to skins, which have already been connected with weaker
oozes.
In this drum it again delivers a part of its tannin and if in this manner again
sunk in its concentration it gets into the next drum, until at last, being of a very
poor concentration the ooze is conveyed into that drum, which has just been filled
with fresh skins.
For this purpose the drums A, B, C, D are provided with a particular extract-
conduit, a waste-water-conduit, an extract-pressure-conduit, and air-pressure-
conduit, so that each drum can be provided with new skins without the proceeding
of any other being interrupted.
It may be supposed that the drums A, B, C, are working, but that the drum D
has been put out of motion for taking out the tanned skins and for providing it with
new ones. Drum A may contain a solution of strong concentration drum B of a
middle one and drum C one of a low concentration.
The skins in drum A. having suffered a through tanning, the valve Z of the air-
pressure-conduit D is opened, so that by opening in the same moment the
valves Q and Q³ compressed air is brought into the drums A and C. In con-
sequence of the over pressure thereby produced in these drums, the solution or ooze
of the drum C being of weak concentration and having acted on fresh skins, to
which it has nearly communicated all its tannin, is pressed by the waste-pipe ³ the
pipes f³, 93 and valves S3 Y³ into the extract-conduit L, which conveys the ooze to
further purposes, whilst the acid, being in the drum A and now sunk to middle
concentration in consequence of its delivery of tannin to the now tanned skins, gets,
after closing the valve Q³ through the waste pipe the pipes f g¹ valves S 1 T 1,
pipe h', heater F, valve R2, tube d and supply pipe a² into the drum B and presses
out from this one the solution which formerly possessed middle concentration but
has now sunk to low concentration for its having communicated the tannin for the
skins, into the drum C.
Then the valve Z being closed, new ooze or acid of strong concentration is

page_text: conducted from the reservoir M through the pipes E, c' the valve Q3 pipe d' and
the supply-pipe a into the drum B, the skins contained therein were before in
communication with a middle ooze.
The latter is brought by the waste-pipe 62, the tubes f, g valves S³, T2 pipe h
heater F, valve R³ tube d³ and supply pipe as to the drum C, whilst the weak
concentrated ooze is pressed from C to the drum D. The latter has meanwhile
been provided with fresh skins and has been put into activity.
As soon as the oozes in the drums B, C, D have acted long enough upon the
skins lying in these drums, so that these skins have been thoroughly tanned, the
valve 2 of the compressed-air-conduit and the valves Q and Q are opened and
the ooze being in the drum D, which has nearly totally delivered its tannin is
pressed by the compressed air through the waste-pipe & pipes f, g, valves S, Y
into the extract-conduit L, by which it is led off in order to serve for further
proceedings.
The ooze being in drum B, which has sunk to middle concentration is pressed as
the same time to the drum C after the valve Q being closed and the acid from C,
now of a low concentration is pressed to D.
Drum A after having been discharged of its well tanned skins and provided with
new ones; now is put into activity and a stronger concentrated ooze is conducted
from the reservoir M (the valve Z being closed) through the pipes E, c³ valve Q³
pipe, d and the supply-pipe a³ into the drum C, so that the middle concentrated
ooze is pressed from C to D, whilst the ooze of a weak concentration being in D,
gets through the waste pipe 6, pipes f, g valves S4, T* into the conduit U, through
this one into the heater F and from here through pipe e', valve R', pipe d¹ and the
supply-pipe a into the drum A in order to act therein upon fresh skins. Drum B
is mean while put out of activity in order to take out thereof the tanned skins and
to provide drum B with new skins.
In the described manner the drums are put out of activity the one after the
other, and the drums being in activity are always at first provided with acids of
weak, then of middle, and then of stronger concentration, so that the skins being in
the drums are connected with solutions of tannin getting gradually stronger.
Before each drum there, is a heater F¹ to F which the acid must pass before its
entrance into the drum in order to be more or less warmed as circumstances may
require.
The warming itself is effected by means of the winding-pipes s¹ to s¹, which can
be provided with heating steam by a steam-pipe-conduit.
The water-pipe-conduit W is in connection by valves X' to X' and tubes 1 to 1*
with the single heaters and has the purpose, if necessary to bring water to the
solution of the tannin and to diminish the concentration of the ooze.
'
The drums A, B, C, D are provided with perforated edges 2 to 24 Fig. 1 and 2.
In the annular space between the edge and the drum-wall Fig. 2 there are the
supply-pipes a¹ to a' and the waste-pipes b' to b₁.
The perforated edge has the purpose to distribute the solution of tannic acid
entered through the supply-pipe quite equally to the contents of the drum and to
retain little parts of flesh and uncleaning substances from the acid, before its being
pressed into the next drum; the tanning being finished these uncleaning substances
may be removed.
Each of the drums A, B, C, D, is arranged upon trestles H¹, J', H2, J, H³,
J; H, J and strongly connected with a toothed wheel K', K2, K3, K so that if
one of the latter is put into rotation by means of the transmission, the drum being
attached to it which is inactivity rotates by which proceeding an easier and more
equal communication of the skins with the tannin is effected.
The tannic-acid or ooze to be used is warmed in a coop N, from which it gets
into the reservoir M, which, as described before, can be connected with the different
drums.
By means of the described arrangement it is possible to regulate mathematically
exactly and continuously the quantity of the tannin, to be added to the ooze.

page_text: The oozes are used nearly to the last rest. The necessary working expenses
become considerably smaller and also such a quick and tender tauning is performed
as it was impossible till now by all known methods. Skins wanting 40-70 hours
for being tanned in barrels, are tanned by the described method much better in
5-6 hours.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is:
Apparatus for continuous tanning distinguished:
1) By a series of drums A, B, C, D, mounted so as to be able to rotate, and
connected with each other by an extract pipe E or compressed air pipe D', extract
expelling pipe L and circulating pipes U in such a way that the solution of tan of
higher concentration which is employed is continuously driven on the hides of
which tan-solutions of weak and medium concentration have already acted; then
after its concentration has diminished driven through connecting-pipes f¹h', f 12,
f h³, fh,... into the other drums, in order there to act on hides which as yet
have only been attacked by solutions of weak concentration or not at all, until
finally being almost entirely deprived of its tan, it is carried away through extract
expelling pipe L to be used for other purposes.
2) By heaters F1, F2 F3 F4.... which are arranged before the various drums
and must be passed by the tan-solution before its.entry into each drum in order
according to need, to be heated more or less, while the steam necessary
for heating is supplied by a steam pipe D connected with all the heaters, and the
condensed water formed in the heating worm pipes s³, 82, 83, s¹ is carried away by
the condensed water pipe G.
3) By the water pipe W connected with all the heaters and supplying the ooze
in the various drums with water as needed, so that the concentration of the various
solutions can be regulated before they enter the drums.
Dated this 11th day of February
For HERMANN SCHMIDT
and
JULES LANDINI,
Bernhard Brockhues.
For HERMANN SCHMIDT
and
JULES LANDINI,
Bernhard Brockhues.