IMPROVEMENTS IN THE METHOD OF REMOVING HAIRS FROM HIDES AND SKINS, AND IN SOFTENING, PREPARING, AND TANNING SUCH HIDES AND SKINS
Year: 1876

page_text: LETTERS PATENT to John Palmer, of Tranmere, in the County of Chester, for
the Invention of "IMPROVEMENTS IN THE METHOD OF REMOVING HAIRS FROM
HIDES AND SKINS, AND IN SOFTENING, PREPARING, AND TANNING SUCH HIDES
AND SKINS."
Sealed the 2nd June 1876, and dated the 5th April 1870.
PROVISIONAL SPECIFICATION left by the said John Palmer at the Office of
the Commissioners of Patents on the 5th April 1876.
"IMPROVEMENTS IN THE
JOHN PALMER, of Tranmere, in the County of Chester.
METHOD OF REMOVING HAIRS FROM HIDES AND SKINS, AND IN SOFTENING, PRE-
PARING, AND TANNING SUCH HIDES AND SKINS."
My Invention relates to a method of preparing hides and skins so that hides of
any description and however cured can be brought back to their original state
and softness. For instance, wet salted Buenos Ayres hides of sixty pounds, and a
dry hide of thirty-four pounds can be made to weigh when tanned seventy-one
and a half pounds respectively against the forty-three and a half and fifty-one
pounds, which whey are made to do by the liming process as now practised.
Firstly. To prepare hides according to my Invention I first soak the hides, and
then cause them to unhair by using a soda waste liquor instead of lime. To
accelerate this process the liquor inay be warmed to blood heat. The hides are
broken down, or milled and unbaired when ready, but should not be passed forward
until they have been thoroughly softened to the centre. This will be proved by
the discoloration. This point should be very carefully attended to, for if the centre
of the hide is not thoroughly softened the leather will not be as thick or weigh as
heavy as it should, and the tanning will take months instead of weeks.
Secondly. When the hides are softened and swollen as much as they can be I
wash them through water and then "scud," and to further cleanse and purify them
I pass them through a bath of vitriol and water, care being taken either by time
or strength of the vitriol that the centre of the hide is cleaned as well as the
outside.
Thirdly. As vitriol is injurious to the hides and leather I eradicate it by the use
of carbonate of magnesia, chalk, whiting, or milk, either fresh, or after the butter
has been extracted.

page_text: Fourthly. To open the hide whilst tanning so as to enable it to absorb the tan
and also to destroy the dark colours of heinlock extract, divi divi, gambier, and like
substance I use finely ground fustic.
Fifthly. Instead of allowing the leather to drain, naturally taking a long time, I
apply rotary motion so as to drain the hide by centrifugal force, which can be effec-
tually done in a few minutes.
Hides prepared by the before going process will absorb the tan so rapidly that
the thickest of hides need only be in the liquor one month, and from being so
thoroughly softened and freed from extraneous matter warm liquor need not be
used to soften the hides and accelerate the process of tanning, whereby a great
improvement in the colour of the leather results.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said John Palmer in the Great Seal Patent Office on the 30th September
1876.
"
JOHN PALMER, of Tranmere, in the County of Chester. IMPROVEMENTS IN THE
METHOD OF REMOVING HAIRS FROM HIDES AND SKINS, AND SOFTENING, PRE-
PARING, AND TANNING SUCH HIDES AND SKINS."
My Invention relates to a method of preparing hides and skins so that hides of
any description and however cured can be brought back to their original state and
softness. For instance, wet salted Buenos Ayres hides of sixty pounds, and a dry
hide of thirty-four pounds can be made to weigh when tanned seventy-one and a
half pounds respectively, against the forty-three and a half and fifty-one pounds,
which they are made to do by the liming process as now practised.
Firstly. To prepare hides according to my Invention I first soak the hides, and
then cause them to unhair by using a soda waste liquor instead of lime. For
example, I soak the hides in a weak solution of alkali waste, or in a pit from which
the hides have been previously taken to unhair, graduating them as at present
practised in liming. When a new solution is required, I make it in this proportion,
ten pounds of alkali waste, or refuse from a soda manufactory, to fifty gallons of
water, but more or less of the waste may be used as the unhairing is required to be
done in a longer or shorter period. The waste may be boiled or have boiling water
poured upon it. It is then used at the desired temperature, which must not be
higher than blood heat. The hides are broken down or stocked and unhaired when
ready, but should not be passed forward until they have been thoroughly softened
to the centre. This will be proved by the discolouration. This point should be
very carefully attended to, for if the centre of the hide is not thoroughly softened
the leather will not be as thick or weigh as heavy as it should, and the tanning will
take months instead of wecks.
Secondly. When the hides are softened and swollen as much as they can be I
wash them through water and then seud, and to further cleanse and purify them
I pass them through a bath of vitriol, or other like acid and water, in the propor-
tion of one quarter of an ounce to one half an ounce of vitriol or sulphuric or other
like acid to the pound of hide, care being taken either by time or strength of the
vitriol that the centre of the hide is cleaned as well as the outside.
Thirdly. As vitriol is injurious to the hides and leather I eradicate it by the use
of carbonate of magnesia, chalk, whiting, or milk, either fresh, or after the butter
has been extracted. I use the milk as a bath. Whiting I use in equal weight to
the vitriol or sulphuric acid. In the case of magnesia or chalk I use it in propor-
tionate quantities.
Fourthly. To open the hide whilst tanning so as to enable it to absorb the tan
more readily, and also to destroy the dark colours, such as those of hemlock extract,
divi divi, gambier, and like substances, I use finely ground fustic in the proportion
of one half pound to one pound of ground fustic per hide. This in the forward

page_text: handlers or layers will materially quicken the tanning process. To precipitate the
colouring matter in the hemlock extract, I pour boiling water on the ground fustic,
and then mix it with the extract.
Fifthly. Instead of allowing the leather to drain, naturally taking a long time,
I apply rotary motion so as to drain the hide by centrifugal force, which can be
effectually done in a few minutes.
Hides prepared by the foregoing process will absorb the tan so rapidly that the
thickest of hides need only be in the liquor one month, and from being so thoroughly
softened and freed from extraneous matter the process of tanning is greatly
accelerated, also a great improvement in the colour of the leather results, inasmuch
as warm liquors need not be used to soften the hides during the process of tanning.
As the wet salted hide gains twenty-eight pounds by this process, so will a dry
salted hide gain sixty-five per cent., and East India kips very little less, instead
of losing as now about twenty per cent. Market hides will also yield about forty
per cent, more leather.
Having now described and ascertained the nature of my Invention, what I claim
as my Invention is―
Firstly. The use and application of alkali waste for soaking and unhairing hides,
such alkali waste being warmed to about blood heat, either by first boiling the
waste or by pouring boiling water over the waste and then reducing the tempera-
ture as required, substantially in the manner and for the purposes set forth.
Secondly. The use of an acid, such as vitriol, sulphuric, or other like acid to
kill the stains arising from the waste or liquor, substantially in the manner as
set forth.
Thirdly. The use of alkalis, such as carbonate of magnesia, chalk, or whiting to
kill the vitriol or sulphuric or other like acid after its application to hides, sub-
stantially in the manner as set forth.
Fourthly. The use of milk to kill the vitriol or sulphuric or other like acid after
its application to hides, substantially in the manner as set forth.
Fifthly. The use of fustic as an assistant in tanning, substantially as set
forth.
In witness whereof, I, the said John Palmer, have hereunto set my hand and
seal, this Twenty-ninth day of September, in the year of our Lord One
thousand eight hundred and seventy-six.
JOHN PALMER. (L.S.)