AN IMPROVED PROCESS OF TANNING
Year: 1883

page_text: LETTERS PÅTENT to William Clark of the firm of A. M and W. Clark of
53 Chancery Lane in the County of Middlesex Fellow of the Institute of
Patent Agents for an Invention of AN IMPROVED PROCESS OF TANNING
communicated to him from abroad by Gaudenzio dalla Zonca of Venice in
the Kingdom of Italy
PROVISIONAL SPECIFICATION left by the said William Clark at the Office
of the Commissioners of Patents on the 4th August 1883.
" AN
WILLIAM CLARK of the firm of A. M. and W. Clark of 53 Chancery Lane in
the County of Middlesex, Fellow of the Institute of Patent Agents,
IMPROVED PROCESS OF TANNING." [Communicated to him from abroad by
Gaudenzio dalla Zonca of Venice in the Kingdom of Italy]
This Invention relates to a rapid process of tanning hides and skins with
vegetable substances only.
The skins after being cleaned, fleshed and depilated are first colored by
immersion in weak liquor which has served in previous tanning operations to
which is added about five ounces of ground vegetable substances containing tannin
marking 4 to 5 degrees Baumé. The tauning operation is then performed in the
following manner :-
The skins are first sewn together by their opposite edges so as to form a kind
of bag leaving an opening at the hind legs only at which is introduced a mixture
of ground vegetable substances containing tannin. Tho skins are then laid on
their backs in groups for the sake of convenience with all the heads in a line in
large sheds sheltered from strong air currents, care being taken to prevent their
becoming wetted on the outside. The skius may be laid out either upon a long
wooden framing divided into sections or upon a well polished floor of thin wood
covered with felt or other pervious fabric. The framing should be placed at a
slight inclination so that the hind legs may be lower than the hoads. The skins
being thus placed, the liquor from previous tanning operations is thon introduced
through the openings in the legs by means of pipes, the liquor being contained in
cisterus heated by means of steam pipes to a temperature of from 25° to 30°
Reaumur in spring and summer, and to from 30° to 35° in autumn and winter.
A few minutes will suffice in this manner to fill a hundred skins, but the skins
should not at first be filled to more than one third of their capacity and care
should be taken to introduce the liquor at a temperature of 18° Reaumur. The
openings in the back legs are then closed by suitable means and the skins are
shaken either by hand or by mechanical means for some minutes in order that the
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liquor may mix intimately with the tanning mixture of vegetable matters which
has been previously enclosed in the skins. The skins are now allowed to remain
for about an hour after which a fresh supply of liquor is introduced so as to
completely fill up the skins and the shaking is repeated. An hour and a half
afterwards a fresh quantity of liquor is introduced sufficient to fill out the skins,
after which the supply is cut off and the opening in the legs closed by the cock
applied to said opening. The pores of the skins which nearly always have the
grain side outwards will then be seen to open and allow of the liquor exuding,
which after filtering through the fabric and wood is collected in channels provided
for the purpose extending beneath the skins. These gutters are slightly inclined
so as to allow of the liquor being collected and added to that used in the succeeding
operation. These filling and shaking operations are repeated every two hours in
order to compensate for loss of liquor due to drainage and exudation and also to
keep the liquor at a constant temperature of 24° to 25° Reaumur in spring and
summer, and 28° to 30° in autumn and winter.
If the hides are to serve for making stout or light uppers they should be treated
as above described for from 3 to 4 days, and for light soles, saddlery, or thin
straps, for from 4 to 5 days, or from 5 to 6 days for stout straps or thick sole
leather. By cutting the skins with a knife after the lapse of the above periods,
they will bo found to be tanned and with their fibres well impregnated with
tannin.
The skins may then be withdrawn from the tanning chamber and after being
emptied of the liquor and vegetable materials they contained the edges are unsewn.
In order to increase their weight as much as possible and improve their appearance,
they are treated in the following manner :-
If the skins treated are to be used for uppers they are in all cases to be treated
with a liquor which has served in previous tanning operations with the addition
for every kilogramme of dry hide, of one kilogramme of ground vegetable tanning
substances and they are then placed in a large cask driven by steam power which
is made to revolve for a period of three days, care being taken to open and close..
the small openings in the cask every 6 hours to allow of the carbonic acid which
naturally forms to escape. The cask is then closed and revolved for about one
hour. After three days have expired the skins will be perfectly tanned and
prepared and may then be finished in the usual way.
If the hides are to be used for sole leather, saddlery, or straps, they should be
placed in square troughs or basins, and upon them should be poured some of the
liquor which has served in the previous tanning operations to which is added in
the case of light sole leathers or saddlery articles for every kilogramine of dry hide
about ten ounces of ground vegetable tanning substances at about 8 degrees
Baumé, and in the case of strong sole or strap leather, the proportion of vegetable
tanning materials to be added to the liquor would be about five ounces at
25° Beaumé.
The liquor and mixture are prepared two days before immersing the skins and
care should be taken before this is done to intimately mix the liquor and the
vegetable matters. After immersion the liquor and mixture should be slightly
stirred and the skins should be placed with the grain side uppermost.
The liquor should not be in too great abundance but of just sufficient amount
to cover the skins. The skins should be allowed to remain in the liquor for about
eight days care being taken to remove them every day and well drain them before
they are replaced as well as to well stir the liquid and mixture. After this period
has elapsed the skins will be perfectly tanned and prepared ready for the ordinary
finishing treatment.
By means of the process of this Invention skins used for uppers may be
completely tanned in from 15 to 16 days and heavier qualities for sole leather &c
in from 24 to 26 days

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent. filed by
the said William Clark in the Patent Office on the 4th February 1884.
WILLIAM CLARK of the firm of A. M. & W Clark of 53 Chancery Lane in the
County of Middlesex Fellow of the Institute of Patent Agents "AN IMPROVED
PROCESS OF TANNING A communication to me from abroad by Gaudenzio dalla
Zonca of Venice in the Kingdom of Italy
"3
This Invention relates to a rapid process of tanning hides and skins with
vegetable substances only.
The hides and skins after being cleaned fleshed and depilated are first colored
by immersion in weak liquor which has served in previous tanning operations to
which is added about five ounces of ground vegetable substances containing tannin
marking 4 to 5 degrees Beaumé. The operation of coloring requires only about 8
or 9 days instead of several months as in ordinary. The tanning operation is
then performed in the following manner :-
The bides or skins are first sown together by their opposite edges with hemp
or so as to form a kind of bag leaving an opening at the hind legs only at which
is introduced a mixture of ground vegetable substances containing tannin. The
hides or skins are then laid on their backs in groups for the sake of convenience
with all the heads in a line in large sheds sheltered from strong air currents, care
being taken to prevent their becoming wetted on the outside. The hides or skins
may be laid out either upon a long wooden framing divided into sections or upon
a well polished floor of thin wood covered with felt or other pervious fabric. The
framing should be placed at a slight inclination so that the hind legs may be lower
than the heads. The hides or skins being thus placed the liquor from previous
tanning operations is then introduced through connections adapted to the openings
in the legs by means of pipes attached to said connections the liquor being
contained in cisterns heated by means of steam pipes to a temperature of from 25°
to 30° Réaumur in spring and summer and to from 30° to 35° R in autumn and
winter. In this manner a hundred skins may be filled in a few minutes but the
skins should not at first be filled to more than one third of their capacity and care
should be taken to introduce the liquor at a temperature of 18° Réaumur. The
openings in the hind legs are then closed by suitable means and the hides or skins
are oscillated either by hand or by mechanical means for some minutes in order
that the liquor may mix intimately with the tanning mixture of vegetable matters
which has been previously enclosed. The hides or skins are now allowed to
remain for about an hour after which a fresh supply of liquor is introduced until
they are completely filled and the oscillating motion is repeated. An hour and a
half afterwards a fresh quantity of liquor is forced in so as to distend the hides
or skins after which the supply is cut off and the openings in the legs closed by
cocks upon the connections applied thereto. The pores of the hides or skins which
nearly always have the grain side outwards will then be seen to open and allow
the liquor to exude which after filtering through the fabric and wood is collected
in channels provided for the purpose in the floor beneath. These gutters aro
inclined and the liquor is collected and added to that used in the next filling
operation. These filling and shaking operations are repeated every two hours in
order to compensate for the loss of liquor due to drainage and exudation and also
to keep the liquor at a constant temperature of 24° to 25° Réaumur in spring and
summer, and 28° to 30° in autumn and winter.
If the skins or hides are to sorve for making stout or light uppers they should
be treated as above described for from 3 to 4 days and for light soles, saddlery,

page_text: or thin straps for from 4 to 5 days or from 5 to 6 days for stout straps or thick
sole leather. By cutting the skins with a knife after the lapse of the above
periods they will be found to be tanned and with their fibres well impregnated
with tannin.
The hides or skins may then be withdrawn from the tanning chamber and after
being emptied of the liquor and vegetable materials they contained the edges are
unsewn. In order to increase their woight as much as possible and improve their
appearance they are treated in the following manner: _
Skins to be used for uppers are in all cases to be treated with a liquor which
has served in previous tanning operations with the addition for every kilogramme
of dry skin, of one kilogramme of ground vegetable tanning substances and they
are then placed in a large cask driven by steam power which is made to revolve
for a period of three days care being taken to open and close the small openings
in the cask every 6 hours to allow of the carbonic acid generated to escape. Tho
cask is then closed and revolved for about one hour. After three days have expired
the skins will be perfectly tanned and prepared and may then be finished-in the
usual way.
Hides to be used for sole leather, saddlery or straps should be placed in square
troughs or basins and upon them should be poured some of the liquor which has
served in the previous tanning operations to which is added for every kilogramme
of dry hide in the case of light sole-or saddlery leathors about ten ounces of ground
vegetable tanning substances_at.about.8 degrees Beaumé and in the case of strong
sole or strap leather about five ounces of the sume at 25° Beaumé.
The liquor and mixture are prepared two days before immersing the hides or
skins and care should be taken before this is done to intimately mix the liquor
and the vegetable matters. After immersion the liquor and mixture should be
slightly stirred and the hides or skins should be placed with the grain side
uppermost.
The liquor should not be in too great abundance but in just sufficient quantity
to cover the hides or skins. The hides or skins should be allowed to remain in
the liquor for about eight days care being taken to remove them every day and
well drain them before they are roplaced and also stir the liquid and mixture.
After this period has elapsed the hides or skins will be perfectly tanned and
prepared ready for the ordinary finishing treatment.
By means of the process of this invention skins used for uppers may be
completely tanned in from 15.to 16 days and hides for sole leather & in from 24
to 26 days.
Any vegetable substances containing tannin may be employed by so mixing
as to obtain the exact amount of tannin required without exceeding the usual
limit.
Having described the nature of the said invention and the manner of performing
the same 1 declare that what I claim as the invention to be protected by the
hereinbefore in part recited Letters Patent is:-
The improved process of tanning herein before described whereby a considerable
saving in time, labour and tanning material is effected.
In witness whereof I the said William Clark have hereunto set my hand and
seal this Fourth day of February in the year of our Lord One thousand eight
hundred and eighty four.