IMPROVEMENTS IN SOFTENING, UNHAIRING, SCUDDING, PURING, UNGREASING AND PRESERVING HIDES AND SKINS
Year: 1883

page_text: LETTERS PATENT to Alexander Melville 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 IMPROVEMENTS IN SOFTENING,
UNHAIRING, SCUDDING, PURING, UNGREASING AND PRESERVING HIDES AND
SKINS communicated to him from abroad by Jules Louis Moret, of Paris, France
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 16th February 1883.
ALEXANDER MELVILLE 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
IMPROVEMENTS IN SOFTENING, UNHAIRING, SCUDDING, PURING, UNGREASING AND
PRESERVING HIDES AND SKINS. [Communicated to him from abroad by Jules
Louis Moret, of Paris, France]
This Invention relates to the processes for which former Letters Patent have
been granted to me dated respectively March 23rd 1881 (N° 1287) and May 10th
1882. (2213) and consists in improved compositions for softening, unhairing, puring
and ungreasing hides and skins preparatory to the tanning operation, and for
enabling them to be preserved for transport or storage for any requisite length of
time and be subsequently unhaired by a simple steeping in water.
The process of depilation is performed substantially as described in the Specifi-
cation of the last mentioned Patent, that is to say the process comprises two
successive operations vis (1) The unhairing process proper and (2) what is termed
a scudding, puring, and ungreasing operation in which the undergrowth, down, or
remaining short hair left after the first operation, is removed.
The first operation may be performed in either of two ways (except in the case
of sheep skins) that is to say by immersion or by application with a brush or mop,
the strength of the chemical agent employed being adapted in the respective cases
to the mode of use. In the case of sheep skins the composition is only to be
applied with a brush or mop on the flesh side so as to avoid injury to the wool.
The second operation is performed by immersion in a vat or bath for all kinds
of skins.

page_text: The composition for the solutions or liquors to be employed in these two
operations is to be prepared as follows.-I first make a strong solution of caustic
soda (or a solution of a mixture of caustic soda and American potash or ordinary
caustic potash) and heat to from about 180° to 200° F. I then add (stirring the
composition well meanwhile) orpiment or realgar in powder in the proportion
of about 10 to 20% of the quantity of caustic soda or of caustic soda and potash
employed. I may also add quicklime in about the same proportions, the exact
quantities, however, being liable to variation and depending in each case on the
kinds of soda or of soda and potash employed and on the manner in which the
composition is to be applied or used.
The quicklime may however be entirely dispensed with in certain cases.
The composition is allowed to settle and the clear liquor decanted off, this clear
liquor being then diluted for use as follows.
For the first or unhairing operation by application with a brush or mop to the
flesh side the composition is to be reduced to the proper strength by adding water,
the strength for light skins being from about 8° to 14° Beaumé, and for heavy
skins and hides from about 12° to 14° Beaumé.
For unhairing by immersion a vat or bath may be formed by washing the
residue (left after decanting the clear liquor) twice or more until exhausted, stirring
well meanwhile, then letting settle and drawing off clear. With these clear
washing waters added together, I make a saturated solution of caustic-soda or of
caustic soda and potash, as the case may be, which I then reduce with water to
from to 8° Beaumé.
Instead of washing the residue as aforesaid, I may make the vat or bath at once
in the same way as described for the composition itself, the proportions of realgar
or of orpiment in this case being 1 to 5 (more or less) of the quantity of caustio
soda, or of caustic soda and potash employed.
When caustic soda alone is employed in conjunction with the orpiment or realgar,
I may dispense with the quicklime altogether, or use a small proportion only.
When however the mixture of soda and potash in conjunction with the orpiment
or realgar is employed, I should use a larger quantity of the quicklime.
In the second operation (immersion in a vat for removing the under growth or
down, for scudding, puring and ungreasing,) the strength of the composition is
reduced to from about 1° to 4° Beaumé according to the nature of the skin.
For preserving hides and skins and preparing them for unhairing at any
subsequent time by a simple steeping in water, I use a solution of caustic soda or
a solution of a mixture of caustic soda and American potash at 8° to 15° with the
addition of 30 grains (or more) of salicylate of soda or other preservative salt to
every cwt of composition at 10° Beaumé, the composition being in this case applied
either with a brush or mop or by immersion, the hides and skins being left in this
state or dried, according as they are to be kept a greater or less length of time. In
the dried preserved state they may be kept for an indefinite period and may be at
any subsequent time restored to their original green and natural condition by
simply steeping them for about 12 hours in water, when the hair and scud may be
removed without further treatment with chemical agents. The water in which the
preserved hides and skins have been so steeped, serve for preparing the baths or
vats used in the first and second operations
This mode of preservation forms an admirable substitute for the salting treat-
ment hitherto generally used for preserving hides and renders unnecessary the
injurious liming or other treatment for unbairing. The quality of the leather
obtained from hides thus preserved by this improved process, will be found to be
superior to that of hides treated in the ordinary way.
The softening of China hides, East India kips, and other dried hides, is effected
by steeping in a very weak solution (½° Beaume) of either of the above mentioned
compositions.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alexander Melville Clark in the Great Seal Patent Office on
the 16th August 1883.
ALEXANDER MELVILLE 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.
"IMPROVEMENTS IN SOFTENING, UNHAIRING, SCUDDING, PURING, UNGREASING, AND
PRESERVING HIDES AND SKINS A communication to me from abroad by Jules
Louis Moret of Paris, France
"
This Invention relates to the processes for which former Letters Patent have
been granted to me dated respectively March 23rd 1881 (N° 1287) and May 10th.
1882 (N° 2213) and consists in improved compositions for softening, unhairing,
puring, and ungreasing bides and skins preparatory to the tanning operation, and
for enabling them to be preserved for transport or storage for any requisite length
of time and be subsequently unhaired by a simple steeping in water.
The process of depilation is performed substantially as described in the speci-
fication of the last mentioned Patent, that is to say, the process comprises two
successive operations, viz-(1) The unwooling or unhairing process proper, and (2)
What is termed a scudding, puring, and ungreasing operation in which the under-
growth, down, or remaining short hair left after the first operation is removed.
The first operation may be performed in either of two ways (except in the case
of sheep skins) that is to say, by immersion or by application with a brush or
mop, the strength of the chemical agent employed being adapted in the respective
cases to the mode of use. In the case of sheep skins the composition is only to be
applied with a brush or mop on the flesh side so as to avoid injury to the wool.
The second operation is performed by immersion in a vat or bath for all kinds
of skins.
The composition for the solutions or liquors to be employed in these operations
is to be prepared as follows:-I first make a strong solution of caustic soda, about
30° Baumé (or of a mixture of caustic soda and American or ordinary caustic
potash) and heat to from about 180° to 200° F. I then add (stirring the com-
position well meanwhile) realgar or orpiment (disulphide or trisulphide of arsenic)
in powder in proportion of about 10% to 20% of the quantity of caustic alkali
employed. I also add quicklime in about the same proportions, the exact quantities
however being liable to variation and depending in each case on the causticity of
the alkali employed, and on the purpose for which the composition is to be applied.
or used.
°
Instead of proceeding as above described, I may prepare the composition as
follows, using the same proportions. I boil the realgar or orpiment and quicklime
in the proper quantity of water and then stir in the caustic soda or mixture of
caustic soda and caustic or American potash. The composition is allowed to settle
and the clear liquor decanted off, this clear liquor being then diluted for use as
follows: For the first or unwooling or unhairing operation by application with a
brush or mop to the flesh side, the composition is to be reduced to the proper
strength by adding water, the strength being in this case from about 8° to 15°
Baumé. For unhairing by immersion I make the composition in the same way as
described, the proportions of realgar or of orpiment in this case being 1 to 5%
(more or less) of the quantity of caustic soda or of caustic soda and potash
employed. The composition is allowed to subside and the clear liquor decanted
and diluted with water until it marks from 1° to 4° Baumé.
When caustic soda alone is employed in conjunction with the realgar or
orpiment, I should use a small proportion only of quicklime. When however the

page_text: mixture of caustic soda and American potash in conjunction with the realgar or
orpiment is employed, I should use a larger quantity of the quicklime.
In the second operation (immersion in a vat for removing the under-growth or
down for scudding, puring, and ungreasing) the strength of the composition as used
for application by a brush or mop is reduced to from about 1° to 4° Baumé
according to the nature of the skin.
For preserving hides and skins and preparing them for unhairing at any
subsequent time by a simple steeping in water, I use a solution of caustic soda, or
a solution of a mixture of caustic soda and American or caustic potash by them-
selves or in combination with orpiment or realgar, and with or without quicklime,
the composition being in this case applied either with a brush or mop or by
immersion, the hides and skins being left in this state or dried, according as they
are to be kept a greater or less length of time. When used with a mop the
_ strength of the solution would be about 2° to 15° Baumé, but for immersion the
strength would be about 1° to 4° Baume. In the dried preserved state they may
be kept for an indefinite period and may be at any subsequent time restored to
their original green and natural condition by simply steeping them for about
12 hours in water when the hair may be removed without further treatment with
chemical agents.
The water in which the preserved hides and skins have been
BO steeped-serves-for-preparing the baths or vats used in the first and second
operations.
This mode of preservation forms an admirable substitute for the salting
treatment hitherto generally used for preserving hides and renders unnecessary the
injurious liming or other treatment for unhairing. The quality of the leather
obtained from hides thus preserved by this improved process will be found to be
superior to that of hides treated in the ordinary way.
The softening of China hides, East India kips, and other dried hides is effected
by steeping in a very weak solution (/, Baume) of any of the above mentioned
compositions.
I would have it understood that instead of taking realgar or orpiment wherever
mentioned in the foregoing description, I may take white arsenic and sulphur in
the proper proportions and produce the sulphide therefrom in the process of making
the composition as will be readily understood.
Having described the nature of the said Invention and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein before in part recited Letters Patent is.
The manufacture and employment, in and for the softening, unhairing, scudding,
puring, ungreasing and preserving hides and skins of a composition prepared in the
manner herein described with caustic soda or a mixture of caustic soda and caustic
or American potash, together with realgar or orpiment (disulphide or trisulphide of
arsenic) to which quicklime may be added if required, for application substantially
as herein specified, the sulphides being either added to the solution of the alkali or
alkalis, or produced in the process of making the composition as described.
In Witness whereof I the said Alexander Melville Clark have hereunto set my
hand and seal this fifteenth day of August, A.D. 1883.
& M CLARK Gol